SAMOA FLOOD MANAGEMENT ACTION PLAN 2007-2012 - Pacific ...

SAMOAFLOOD MANAGEMENTACTION PLAN2007-2012WITH SPECIFIC REFERENCE TOVAISIGANO RIVER

Prepared by:MINISTRY OF NATURAL RESOURCES AND ENVIRONMENTwww.mnre.gov.wsin collaboration withPACIFIC ISLANDS APPLIED GEOSCIENCE COMMISSIONc/o SOPAC SecretariatPrivate Mail BagGPO, SuvaFIJI ISLANDShttp://www.sopac.orgPhone: +679 338 1377Fax: +679 337 0040www.sopac.orgdirector@sopac.orgFlood management Action Plan 2007ii

AcknowledgementThe development of the Flood Management Action Plan was attained upon the invaluablesupport and knowledge of Assistant Chief Executive Officers of the Ministry of NaturalResources and Environment Mr Mulipola Ausetalia Titimaea, Meteorology Division; MrSuluimalo Amataga Penaia, Water Resources Division; and Mr Tagaloa Jude Kohlhase,Planning Urban Management Agency.SOPAC under the EDF8 Project and HR Wallingford Ltd. provided technical assistance inthe development of the Plan in collaboration with the Government of Samoa.Further acknowledgement to other key government agencies, private sectors, NGOs andrelevant national donor funded projects such as WaSSP and ADB TA on Drainage andSanitation for their immense contribution to the formulation of the Plan.Flood management Action Plan 2007iii

Foreword[to be completed by Water Resource Division (MNRE)]Flood management Action Plan 2007iv

Table of Contents1. Introduction ................................................................................................................. 11.1. Scope ................................................................................................................... 11.2. Purpose................................................................................................................ 31.2.1. Goals and Objectives .................................................................................... 31.3. Guiding Principles ................................................................................................ 41.4. Frameworks that Encompass the FMAP .............................................................. 51.4.1. The Regional Context.................................................................................... 51.4.2. The National Context..................................................................................... 51.4.3. Issues to be addressed ................................................................................. 61.4.4. Existing Policies and Legislation that Provide for Flood Management ........... 71.4.5. Linkages with other National Projects ............................................................ 71.5. Implementation Strategy ...................................................................................... 91.5.1. Implementing Agencies ................................................................................. 91.5.2. Coordinated In-country Implementation, Monitoring and EvaluationProgramme ................................................................................................................. 92. Background to flood management in the Vaisigano River catchment and Apia 112.1. Introduction ........................................................................................................ 112.2. Hydrological monitoring in the Vaisigano River catchment ................................. 112.2.1. Rainfall stations ........................................................................................... 112.2.2. Flow monitoring stations ............................................................................. 122.3. Elements at risk of flooding in the lower Vaisigano floodplain ............................. 122.4. Previous flood risk management studies and measures ..................................... 133. Flood mitigation measures ..................................................................................... 163.1. Introduction ........................................................................................................ 163.2. Structural mitigation measures ........................................................................... 173.2.1. Flood embankments and walls .................................................................... 183.2.2. Flood storage .............................................................................................. 213.2.3. By-pass or diversion channel ...................................................................... 253.2.4. Increasing channel conveyance .................................................................. 273.2.5. Pumping ...................................................................................................... 283.2.6. River maintenance ...................................................................................... 283.2.7. Flood proofing of buildings .......................................................................... 293.3. Non-structural mitigation measure options ......................................................... 303.3.1. Development control ................................................................................... 303.3.2. Flood forecasting......................................................................................... 363.3.3. Flood warnings ............................................................................................ 373.3.4. Flood insurance........................................................................................... 37Flood management Action Plan 2007v

3.3.5. Improving flood preparedness and response ............................................... 383.3.6. Land use change......................................................................................... 383.4. Summary of actions that are required ................................................................. 394. Flood Management Action Plan Matrix .................................................................. 425. References ............................................................................................................... 546. Annexes ................................................................................................................... 55Annex 1: The Process carried out in Samoa to develop the Plan .................................. 55Annex 2: Glossary of Definitions ................................................................................... 56Annex 3: Stakeholder Consultation Workshop for the FMAP – List of Participants ........ 59Annex 4: Consolidation of existing statutory and non-statutory flood risk reductionactivities in Samoa ........................................................................................................ 62List of TablesTable 1-1: Flood Management Action Plan Goals............................................................... 3Table 2-1: Rainfall gauges in the Vaisigano catchment .................................................... 12Table 2-2: Number of people and buildings at risk in the lower Vaisigano floodplain ........ 12Table 3-1: Design flood flows for the Lower Vaisigano at Apia ......................................... 17Table 3-2: Summary of embankment/wall heights ............................................................ 20Table 3-3: Summary of the preliminary volume of fill material required for the floodembankments in the lower Vaisigano River ............................................................... 20Table 3-4: Number of people and properties protected by building an embankment or wallbetween the Leone and Vaisigano Bridges ............................................................... 21Table 3-5: Preliminary storage volumes and heights required for an on-line storage damsfor flood storage ........................................................................................................ 22Table 3-6: Number of people and properties protected by building an embankment damin the upstream reaches of the catchment ................................................................. 23Table 3-7: Preliminary dimensions of a flood diversion channel for the Lower Vaisigano. 27Table 3-8: Guidance on the degree of flood hazard .......................................................... 33Table 3-9: Actions required for structural mitigation measures ......................................... 40Table 3-10: Actions required for non-structural mitigation measures ................................ 41List of FiguresFigure 1-1: Map of Samoa showing the location of the Vaisigano River catchment ............ 2Figure 1-2: Links between National Development Planning, Budgetary Process and FloodManagement ............................................................................................................... 6Figure 1-3: The responsibilities of key sectors for flood risk management are crosscuttingwith particular functions identified in the FMAP ........................................................... 8Figure 2-1: Flood wall at Aggie Greys Hotel at the mouth of the Vaisigano....................... 14Figure 2-2: Flood wall and bank protection for commercial property on a tributary of theFlood management Action Plan 2007vi

Vaisigano River ......................................................................................................... 15Figure 3-1: Example of a cross-section through a typical flood defence embankment ...... 18Figure 3-2: Location of flood embankments for the lower Vaisigano River downstream ofLeone Bridge ............................................................................................................. 19Figure 3-3: Cross-section through the flood embankments for the Lower Vaisiganodownstream of Leone Bridge ..................................................................................... 20Figure 3-4: Indicative location for upstream flood storage ................................................. 23Figure 3-5: Cross-section through a typical earth embankment dam ................................ 24Figure 3-6: Illustration of the estimation of flood storage for the 1 in 100 year floodhydrograph ................................................................................................................ 24Figure 3-7: Possible route for a flood diversion channel ................................................... 26Figure 3-8: Cross-section of a possible flood diversion channel for the lower VaisiganoRiver ......................................................................................................................... 26Figure 3-9: Flood depth map for the 1 in 20 year flood for the lower Vaisigano ................ 31Figure 3-10: Flood depth map for the 1 in 100 year flood for the lower Vaisigano............. 32Figure 3-11: Flood hazard map for the 1 in 20 year flood for the lower Vaisigano............. 34Figure 3-12: Flood hazard map for the 1 in 100 year flood for the lower Vaisigano........... 35Flood management Action Plan 2007vii

Abbreviations and AcronymsThe following abbreviations and/or acronyms are used throughout this Plan.Abbreviation/Acronym DescriptionACPAsia, Caribbean and PacificAGAttorney GeneralCHARMComprehensive Hazard and Risk ManagementCSDCorporate Services DivisionDACDisaster Advisory CommitteeDMODisaster Management OfficeDTMsDigital Terrain ModelsEDFEuropean Development FundEIAEnvironmental Impact AssessmentEPCElectric Power CorporationEUEuropean UnionFDForestry DivisionFMAPFlood Management Action PlanGISGeographic Information SystemsICTInformation and Communication TechnologyIPESInstitute of Professional Engineers of SamoaLMDLand Management DivisionMESCMinistry of Education, Sports and CultureMNREMinistry of Natural Resources and EnvironmentMOAMinistry of Agriculture and FisheriesMWCSDMinistry of Women, Community and Social DevelopmentMWTIMinistry of Works, Transport and InfrastructureNDMPNational Disaster Management PlanNGOsNon Government OrganisationsNUSNational University of SamoaNWSNational Water StrategyPUMAPlanning and Urban Management AgencySNDMPSamoa’s National Disaster Management PlanSIAMSamoa Integrated Asset Management ProjectSLMNAPSustainable Land Management National Action PlanSOPACPacific Islands Applied Geoscience CommissionSTASamoa Tourism AuthoritySWASamoa Water AuthorityTINTriangulated Irregular NetworkTSDTechnical Services DivisionWaSSPWater Sector Support ProgrammeWRDWater Resources DivisionFlood management Action Plan 2007viii

1. IntroductionThis Flood Management Action Plan (FMAP) was developed in response to theGovernment of Samoa’s request for flood management assistance on particularly inthe urban areas surrounding the capital of Apia. The need for flood management wasfirst identified in Samoa’s work plan for the EDF 8 project in WS 3.4 and 3.5pertaining to hazard assessment and risk reduction. The Plan has been developedas part of the regional EDF 8 Project Reducing Vulnerabilities in the Pacific ACPStates, executed by the Secretariat of the Pacific Islands Applied GeoscienceCommission (SOPAC). The implementation of the Plan should also consider thefollowing documents, which had been developed in conjunction:• Samoa Floodplain Management: A Guideline for Planning and DevelopmentAssessment 2007• Samoa - Capacity Building in Flood Risk Management – Technical reportSOPAC/EDF8 Project No : ER0069aSamoa’s location and characteristics together with its economic and technologicalcapacity contributed to its vulnerability to a number of natural and technologicalhazards including flooding. A risk analysis carried out for the Disaster ManagementPlan (NDMP) 2006-2009 indicated that ‘floods’ as a result of heavy rain were rankedas a ‘high risk’ event.The economic cost of the 2001 flood was estimated to be over 11 million Tala. As thenumber and cost of floods continues to rise, specifically in Apia the centre for manybusinesses, improving the management of floodplain areas to reduce flood riskbecomes even more critical. All too often, after floodwaters have subsided, theemphasis has been placed on rebuilding structures and trying to restore flood victims'lives back to normal as quickly as possible. Unfortunately, these flood victims haveoften rebuilt their structures in their previous "at risk" conditions. The Government ofSamoa is now seeking to integrate numerous programmes to address Apia’s floodproblems and reduce future flood risks and costs.1.1. ScopeThe flood management process is countrywide, with particular focus on the lowerVaisigano watershed and coastal area (Figure 1.1). The central administrative levelof the national government underpins the scope of this Plan applicable countrywide,which mean that the non-structural actions such as policy recommendation, capacitybuilding, information management and communication, flood forecasting and warningand community awareness and education apply to other river catchments in Samoa.The plan discusses various structural measures to mitigate flood in the lowerVaisigano. The methods by which the structural mitigation options have beenidentified could also be applied to other river catchments across Samoa. The FMAPhas two main components:Component 1 – Flood Risk ReductionFlood risk reduction or mitigation includes prevention, protection and / or adaptation.However, floods cannot be totally prevented or mitigated by structural means. Hence,integrated flood management is important combining structural and non-structuralmeasures, such as adapting to flood risks and implementing development control inflood prone areas.Component 2 – Flood Emergency ManagementFlood emergency management addresses preparedness (including flood forecastingFlood management Action Plan 2007 1

and warning), response (moving to higher grounds) and recovery (cleaning andrebuilding after floods) before, during and after flood events.0 km30 kmSamoaSavaiiVaisiganoRiver catchmentApiaPacific OceanUpoluApiaHarbourLower Vaisigano catchmentbetween Leone Bridgeand Beach Road0 kmVaisiganocatchmentboundary5 kmFigure 1-1: Map of Samoa showing the location of the Vaisigano River catchmentFlood management Action Plan 2007 2

1.2. PurposeThe purpose of the Plan is to assist Samoa in attaining its sustainable developmentgoal of “improving quality of life for all” 1 through developing a sustained level,integrated and coordinated flood risk management plan. Special emphasis is on thelower Vaisigano River catchment as a pilot area and specific actions arerecommended to be in line with the overarching goal. This Plan identifies actions forGovernment agencies, the private sector, NGOs and communities responsible forflood and floodplain management that can assist in reducing flood risks to theSamoan people and their property, as well as improving public safety and enhancingthe environment.1.2.1. Goals and ObjectivesThe overall goal of the Action Plan is to reduce social, economic and environmentalimpacts of floods on the people of Apia thereby facilitating the achievement ofnational development goals. Table 1-1 sets out six goals of the Action Plan.Table 1-1: Flood Management Action Plan GoalsGoal 1Goal 2Goal 3Goal 4Goal 5Goal 6Flood Risk ReductionFlood Preparedness and Early WarningCapacity BuildingTechnological Information ManagementSustainable Watershed ManagementFlood GovernanceSpecific objectives of the Plan are to:o Identify and map the flood hazard within the lower Vaisigano River catchmento Identify flood risk management options and indicate how these may beassessed in more detailo Strengthen a nationally coordinated flood forecasting and warning systemso Support public outreach and educations activities to improve awareness offlood risk and hazard and promote recommended preparedness actionscommunities can take to reduce risks to themselves and to otherso Manage activities in floodplains in a manner compatible with multiple andcompeting uses, including existing and proposed urban development withinApia.o Strengthen capacity of the Ministry of Natural Resources and Environment, inparticular Water Resources Division, PUMA, Meteorology Division and DMOand other relevant agencies to provide consistency in flood risk managemento Incorporate flood risk management in the national planning and budgetaryprocesses1 2005-2007 Strategy for Development of SamoaFlood management Action Plan 2007 3

o Update the Action Plan regularly and employ adaptive managementstrategies in order to take full advantage of scientific and technologicaladvances, and to use the best available floodplain management practices,principles and information1.3. Guiding PrinciplesThe guiding principles are based on integrated watershed management approachand technical understanding of the characteristics of floodplain in Samoa. They serveas a reference point for the evaluation of flood risks, identifying the range ofmanagement alternatives and developing appropriate actions.The key guiding principles include:o Flooding is a development issueo Flood management requires a whole of government/country approach,involving partnership between and amongst government agencies, donors,communities/land owners and the private sectoro Adopting a programmatic and integrated approach covering all aspects ofFlood Management from risk reduction 2 to preparedness, response andrecoveryo Flooding is a natural processFlooding is a natural process that provides many benefits, but severe floods alsohave disastrous impacts on people, livelihoods, infrastructure and ecosystems.Flooding poses a risk when people and property occupy areas that are subject toinundation, bank erosion or channel migration. Risk can most effectively be reducedthrough comprehensive and integrated flood management actions that employ bothstructural and non-structural approaches to create a safe, effective and sustainablemeans for conveying floodwaters and that are consistent with other uses that rely onnatural river processes.o Flood damage creates financial costs for both the public and private sectors.Effective flood management can reduce long-term damage costso Actions in the upland portions of watersheds impacts flooding and channelmigration within the river corridorFactors that lead to flooding begin upland of the rivers and streams. The conversionof forested land to grass or impervious surface increases the speed and quantity ofstormwater runoff. In addition, forest loss and grading that changes the naturaltopography of the landscape can alter the location at which water leaves a site. Flood(stormwater) design standards should be applied to upland development to minimiseflood impacts at lower elevations.o Good governance, policy context and legislative backing clarifying roles andaccountabilities for flood management activities recognising interconnectivityand interactions between and amongst government agencies, sectors, andcommunities2 This includes prevention, mitigation and adaptationFlood management Action Plan 2007 4

1.4. Frameworks that Encompass the FMAP1.4.1. The Regional ContextSamoa and other Pacific Leaders acknowledges the vulnerability of the Pacific todisaster, and the need for a shift towards treating disaster as a development issue toan integrated approach on disaster risk management. The following regionalframeworks endorsed this shift in focus:o 2005 the regional Disaster Risk Reduction and Disaster Management (DRR &DM) Framework for Action, 2006-2015 which mirrors the Hyogo Frameworkfor Action 2005-2015: Building the Resilience of Nations and Communities toDisasters, and which draws on the guidance set by the Yokohama Strategyfor a Safer World (1994) and the International Strategy for Disaster Reduction(ISDR) 3 .o UN Framework on Climate Change Convention (UNFCCC)o The Forum Economic Ministers and the Forum Leaders have alsoacknowledged disaster as a development issue in 2003.The Kalibobo Road Map produced by the Forum Leaders Meeting in 2005, alsocalled for the operationalisation of these regional frameworks at the national level. Inaddition, member countries will strengthen national capacity on preventativemeasures, as well as effective and timely post disaster response and rehabilitation.1.4.2. The National ContextThis Action Plan is in line with the Samoa Disaster Risk Management National ActionPlan and links to other relevant key sector plans, national development plans andbudgetary process must be articulated. This Plan also compliments sections 2.1.1.8and 2.1.1.9 of the existing Samoa’s National Action Plan for combating desertificationby providing the flood management issues that was lacking in the sustainable landmanagement NAP.Figure 1-2 illustrates the linkages between this Action Plan and NationalDevelopment Plans and budgetary process, Disaster and Sector Plans and the needto incorporate the FMAP into key agencies corporate/business plans.3 ISDR, when mentioned alone, refers to the Strategy. References to the system, the secretariat andplatforms are specifically indicated.Flood management Action Plan 2007 5

NATIONAL DEVELOPMENT PLANS AND POLICIESFlood management as apriority development issueis coveredNATIONAL DEVELOPMENT FISCALAND BUGETARY PLANSResourcesallocation includingFlood managementpioritiesSECTOR/CROSSSECTORAL PLANSFlood managementAction PlanMINISTRY/DEPARTMENT/AGENCYCORPORATE/BUSSINESS PLANSFlood managementimplementionprogramme with actionsforthe Plan periodFigure 1-2: Links between National Development Planning, Budgetary Process andFlood Management1.4.3. Issues to be addressedThe key issues identified during various consultations, and in past assessment,reports on disaster and flood risk management are:o Flooding is a severe and frequent risk to major parts of Apiao Traditional Focus on Response and recovery from disasters- Lack of appropriate incentives- Short term costs versus long-term payoff- Relying on assistance at times of disaster (dependency)o Lack of town planning in Apia - many commercial and residentialproperties are developed on floodplaino Relevant government policy, organisational structures and legislativeframework reflecting connectivity and linkages in flood riskmanagement are still evolving such as the recent restructure this year(2006) of the MNRE to include PUMA, Forestry, and Meteorology.o Inadequate coordination and integrated planning among agencies thathave some responsibilities for flood risk reduction.o Insufficient human resources and capacity (both in the number of staffand in the skill required) to sustain the effectiveness of the Plano Constraints in budgetary allocation to mitigation activitieso Weak monitoring and early warnings to communities at risko Hydro-meteorological data is sparse with a high degree of uncertainty(lack of, or inadequate, quality information)Flood management Action Plan 2007 6

1.4.4. Existing Policies and Legislation that Provide for FloodManagementAlthough, existing policy or legislation do not explicitly addresses flood managementas the sole responsibility of a single agency; the following if integrated could assist inflood management:o Planning and Urban Management Act 2004o EIA regulations 1998o Watershed Protection and Management Regulations 1991o Disaster and Emergency Management Act 2006o Code of Environmental Practice 2001o Draft Housing Guidelines 2003o Draft Building Regulations 1992o National Building Codeo Water Act 19651.4.5. Linkages with other National ProjectsFour relevant national projects are currently implementing in Samoa. These are:o The Asian Development Bank (ADB) funded project entitled “SamoaSanitation and Drainage Project (SSDP)”;o The ADB Technical Assistance (TA) project “Institutional Strengthening forDrainage and Wastewater Management” (4229-SAM);o The EU funded Water Sector Support Programme (WaSSP).o The World Bank funded Samoa Integrated Asset Management Project (SIAM)Efforts were made by the SOPAC project as well as these three other projects toensure complementarities and synergies through consultation and meetings. TheApia sanitation and drainage project address flooding in specific low-lying areas ofApia. Outputs from the drainage phase of the project will include:o Improvement to floodways;o Rehabilitation of existing drains;o Installation of water gauges to for flood monitoring.The ADB TA on institutional strengthening for drainage and wastewater managementprovides technical assistance in terms of capacity building to key agencies involvedincluding the SWA, MWTI and MNREThe purpose of the EU funded Water Sector Support Programme (WaSSP) is toaccelerate achievement of water sector policy goals and objectives and morespecifically to improve the quality of public health through improved water servicesand the sustainable management of water resources. Expected outcomes of thisproject are as follows:o Establish an effective and skilled Water Resources Division;o Develop a Water Resources Management Strategy;o Environmentally sensitive development of water resources;o Improved conservation and protection of water catchment areas and waterresources;o Improved assessment and monitoring of water resources.Flood management Action Plan 2007 7

Figure 1-3 shows the links between donor funded projects and responsibilities ofgovernment agencies in various aspects of flood management in Samoa.Step 1.Identifying and knowingFlood riskEarlyWarningWater ResourcesDivision(Hydrology)MNREMNational DisasterManagement Office NDMOMNREMIntegratedFlood RiskManagement(mitigation,preparedness,response andrecovery)FloodForecastingEarlyWarningandAwarenessMeteorologicalDivisionMNREMThe WaSSPProject deals withthe broader watermanagementframework, whichwill havecomponents forflood managementthrough assessingflood riskThe SOPAC EDF8 project - hasdealt with floodmanagement andWaSSP should beable to pick upsome of theActions in thisPlan forimplementationStep two:Users of flood riskinformation – infrastructuredesigns and developmentprocessEngineeringdesigns anddevelopmentconditionsinformationMinistry of WorksTransport andInfrastructure(MWTI)IntegratedFlood RiskManagement(mitigation,preparedness,response andrecovery)ServicesmaintenanceanddeliveryPublic HealthMinistry ofHealthThe ADB “SamoaSanitation andDrainage Project”TA “InstitutionalStrengthening forDrainage andWastewaterManagement” andWaSSPGuidelines andAction Plandeveloped by theSOPAC EDF 8projectPUMAMNREMPublicinformation toreduce lossof asset,propertiesand lifeandSWAEPC(all three projectscontributed toflood riskmanagement)Figure 1-3: The responsibilities of key sectors for flood risk management arecrosscutting with particular functions identified in the FMAPFlood management Action Plan 2007 8

1.5. Implementation StrategyThe Plan has identified key strategies and actions to improve flood mitigation, floodforecasting and flood warning; and provide for effective emergency management offloods.The implementation of the Plan requires commitments from the Government ofSamoa and support from key sectors at the national levels. Active involvement ofcommunities and private sector stakeholders in the process and in taking action toreduce their vulnerabilities is also essential to the successful implementation of thePlan. A detailed implementation plan will be developed subsequent to the formalendorsement of the Plan.1.5.1. Implementing AgenciesKey ministries involved in flood risk management are the MNRE, MWTI and the MAF.Lack of coordination and collaboration among these three ministries and among thedivisions within a ministry need to be addressed to maximise the use of resourcesand skills available either nationally or through donor funded projects.The Disaster Advisory Committee has the overall responsibility to coordinatepreparedness measures for any hazard. Currently, it seems that the Meteorology isresponsible for forecasting flood and giving flood warning to three bodies, the media,Disaster Management Office and Disaster Advisory Committee (NDMP 2006). It isnot clear however, on who is responsible for the level of flood warning given to thepublic.The responsibility for the collection and management of hydrological data lies withthe Water Resources Division, MNRE. Although the Division does not undertake andimplement flood management programmes there is a regular flow gauging onVaisigano river at Alaoa East station. In addition the Hydrology Section carryoutfortnightly flow gauging at two operating weir stations, spot flow gauging at selectedsites as requested by SWA; and data analysis and estimation of flow. There ispresently no overall strategy in place for the systematic and prioritised collection,storage and analysis of water resources and watershed data, for its use in waterresources and watershed management decision making.1.5.2. Coordinated In-country Implementation, Monitoring andEvaluation ProgrammeThe following are required for a co-ordinated in country implementation, monitoringand evaluation programme.o Development of a detailed implementation plan for each of the Actions of theFMAP identifying the responsible agency, completion time, and resourcesrequirements.o Incorporating the relevant implementation programme into each ministerial andsectoral corporate/bussiness plans for implementation.o Identifying capacity development needs of government agencies, private sector,NGOs and communities for the implementation of the FRMAP.o Undertaking annual review of progress against the Plan and its effectiveness andadjust as necessary involving in-country participants and Samoa’s DevelopmentFlood management Action Plan 2007 9

Partners.o MNRE is committed to lead and coordinate the implementation of the planAnnex 1 summarises the process undertaken to develop the FRMAP, Annex 2contains definitions key words and concepts used in this Plan, Annex 3 is the list ofworkshop participants for the development of the guideline and Action Plan andAnnex 4 is a Consolidation of existing statutory and non-statutory flood risk activitiesin Samoa.Flood management Action Plan 2007 10

2. Background to flood management in the VaisiganoRiver catchment and Apia2.1. IntroductionThe Vaisigano River catchment drains an area of approximately 34 km 2 . The lengthof the main river is approximately 12.5 km and the catchment is 5 km wide at itswidest section. The Vaisigano River flows north, bisecting the capital city of Apiawhere it discharges into the sea. The gradient of its lower reaches means that it istidal for a maximum of approximately 500 m upstream from the river mouth. The tidalrange at the mouth of the river typical varies between from about to 0.6 m to 1.0 mabove mean sea level to 0.25 m to 1.5 m above mean sea level. The VaisiganoRiver is one of the main sources of water supply for Apia. The river also feeds twohydropower stations that supply most of Apia’s electricity.Detailed historical data on the frequency and extent of flooding is limited. A recentSOPAC study records a long history of flooding in Apia (Yeo 2001). Severe floodswere reported in 1939, 1974, 1975, 1982, 1990, 1991 and 2001. More recentlyflooding of Apia occurred in February 2006, which was the result of surface waterponding and poor drainage rather than fluvial flooding from the Vaisigano River. The2001 flood was particularly severe, with estimated 1,300 buildings damagedexceeding Samoan Tala 11 million of direct damage.There appears to have been much speculation that tidal levels have a significanteffect on peak flood water levels in the lower Vaisigano River. The highest recordedtide level in Apia Harbour in the past 12 years was approximately 1.67 m abovemean sea level. Owing to the size of the peak flow at the downstream end of theVaisigano River the tidal water level has no impact on upstream flood water levelseven for a 1 in 2 year flood event.2.2. Hydrological monitoring in the Vaisigano RivercatchmentThis section gives a brief overview of the hydrological monitoring that is carried out inthe Vaisigano catchment. It should be noted that there is requirement for long-term,sustainable investment not only in improving and maintaining the hydrometeorologicalnetwork but also in increasing the capacity of Water Resources andMeteorology Divisions not only in data collection, but in also in archiving and backingup precious past records and providing a degree of quality control over the datacollected.2.2.1. Rainfall stationsThere are a number of rainfall stations in or adjacent to the Vaisigano Rivercatchment. These are listed in Table 2-1.Flood management Action Plan 2007 11

Table 2-1: Rainfall gauges in the Vaisigano catchmentStationElevationPeriod of record(m above mean sealevel)Afiamulu 720 1903-07, 1947-Alaoa Pond 260 1958-Apia 2 1890-Moamoa 100 1906-1908, 1913-1914,1962-Nafanua 150 1965-Owing to the size of the Vaisigano catchment and the intensity of the rainfall inSamoa rainfall intensity data is required to generate flood hydrographs using rainfall– runoff models. An analysis of daily rainfall is not particularly useful when it comesto flood modelling for the Vaisigano. Of the above rainfall stations only two, Apia andAfiamulu record rainfall intensity.2.2.2. Flow monitoring stationsThe Alaoa East gauging station is the only functioning gauging station in theVaisigano catchment. For details of other, now defunct gauging stations, Reference** should be referred to. At Alaoa East water levels are recorded continuously via achart and pen recorder linked to a stilling well upstream of the abandoned watersupply intake which comprises a broad crested weir which is silted up. It has beenestimated that a catchment area of approximately 17.3 km 2 drains to this gauge.Flow gauging is undertaken regularly at Alaoa East. However, although the station isunlikely to be by-passed at high flows, the stage versus discharge curve at the site(i.e. the relationship between water level and discharge) is questionable, especiallyfor estimating flood flows. The station has approximately 22 years of flow dataavailable.2.3. Elements at risk of flooding in the lower VaisiganofloodplainThere are numerous elements at risk in the lower Vaisigano floodplain. Using theflood extent maps produced as part of this action plan, the affected number of peopleand buildings could be identified as shown in Table 2.2.Table 2-2: Number of people and buildings at risk in the lower Vaisigano floodplainReturn period(years)Number of people at risk Number of buildings atrisk1 in 2 1139 2441 in 5 1382 2961 in 20 1536 3291 in 50 1596 3421 in 100 1634 350The hydraulic modelling of the lower reach of the Vaisigano River has indicated thatduring rare flood events it is possible that Lelata, Leone and the Vaisigano Bridge willovertop causing them damage. The amount of damage that these structures wouldincur is difficult to quantify.Flood management Action Plan 2007 12

2.4. Previous flood risk management studies and measuresThere have been limited studies into flooding of Apia and Vaisigano River catchment.The most relevant recent studies include:o Flood study of the occurrence 15 to 16 April 2001 flooding areas of the Apiatownship by Apia Management Services carried out in 2001.o A review of flooding in Apia, Samoa, April 2001 by Dr Yeo produced for the SouthPacific Applied Geoscience Commission (SOPAC) in July 2001.o A report by Kammer for the Samoan Hydrological Services produced in 1975 onthe storm and floods of 16 to 18 November 1974 in Western Samoa.In terms of controlling development in flood prone areas, in September 2006, thePlanning and Urban Management Agency (PUMA) of the MNRE produced adocument entitled “Draft guidelines for the development of land adjoining rivers,streams and on flood prone land and priority actions for mitigating drainage impactsin the catchments of urban Apia”. These state the following:Development within flood prone land shall be designed to minimise the impact of thepassage of water through drainage channels and floodways. In assessing adevelopment application, PUMA shall take into account:o Whether or not the development will adversely affect flood behavior resulting indetrimental increases in the flood prone land, or on adjoining development orproperties outside the flood prone lands.o Whether or not the development will alter local flow distributions and velocities tothe detriment of other properties or the environment in the flood prone lands.o Whether the development will enable safe occupation of the flood prone lands.o Whether or not the development will detrimentally affect the role of rivers andstreams as a floodway including avoidable erosion, siltation, destruction ofvegetation or a reduction in the stability of the banks of the rivers and streams.o Whether or not the development is compatible with the function of the affectedrivers or streams including drainage channels and floodways.In the case of development involving the excavation or filing of land, whether or notthe development:o Will detrimentally affect the existing drainage patterns and soil stability in the localarea.o Will significantly impact on the likely future use or redevelopment of the lando Will adversely impact on the existing and likely amenity of adjoining properties.Will adversely affect any river or stream or environmentally sensitive areas includingmangroves.o Habitable floors rooms in any development (including septic tanks) are to havefloor levels of 300 mm above the estimated flood level resulting from a 1 in a 100year flood.o For works considered as significant by PUMA, a drainage and stormwater planincluding drainage plans for physical works shall be prepared by a qualifiedperson (that is, a person who is a member of the Samoan Institute of Engineers),such drainage and stormwater assessment plan to include at a minimum:Flood management Action Plan 2007 13

o An existing flood assessment (including existing flood levels and existingdrainage), ando A future flood assessment (including future flood levels, future drainage systemand design and mitigation options to minimise impacts).The onsite drainage system shall be designed to ensure that downstream flows arerestricted to pre development levels unless otherwise approved by the responsibleauthority.”There as been little in the way of mitigation measures implemented in the lowerVaisigano River catchment. The only structural measures of note are a flood wallbetween one and two metres high constructed to protect Aggie Greys hotel, shown inFigure 2-1, and a flood wall built on a tributary of the Vaisigano built to protect acommercial development. This is shown in Figure 2-2.Figure 2-1: Flood wall at Aggie Greys Hotel at the mouth of the VaisiganoFlood management Action Plan 2007 14

Figure 2-2: Flood wall and bank protection for commercial property on a tributary ofthe Vaisigano RiverFlood management Action Plan 2007 15

3. Flood mitigation measures3.1. IntroductionThere is a wide range of possible measures for managing floods. These cover suchitems as structural measures which generally involve some type of construction (forexample, flood defence embankments and walls) and non-structural measures suchas flood warning, land use planning, development control and building control.This chapter details the various floodplain mitigation measures considered, inparticular for the lower Vaisigano River catchment including their advantages andpotential disadvantages. The actions required to investigate the various mitigationmeasures in more detail are also outlined.Structural measures considered include:o Flood walls and embankments.o Upstream flood storage.o The use of a by-pass channel.o Increasing the channel conveyance.o Improving the channel maintenance.o Pumping.o Flood proofing of new and existing buildings and other assets.Non-structural measures considered include:o Development control, which includes the avoidance of developments onfloodplains or the protection of new developments.o Flood forecasting and warning.o Floodplain zoning, to link land use with the flooding function of different parts ofthe floodplain.o Flood insurance.o Raising the awareness of flood risk and preparedness of individuals andorganisations to respond to a flood emergency. This includes the floodplainpopulation, floodplain managers and the emergency services.o Land use change.A preliminary assessment of a number of these measures has been made for theVaisigano River catchment using the results of the HEC-HMS hydrological model anda one dimensional HEC-RAS hydraulic model.Mainly due to a lack of data, the various measures have been described in isolation.However, a fundamental principle of effective flood management is that managementmeasures should not be considered in isolation. Rather, they need to be consideredcollectively on a integrated risk management basis in order to provide the bestcombination of measures for managing flood risk on floodplains taking account of thefollowing:o Their interactions.o Their suitability and effectiveness.o Economic effectiveness.o Social impacts.o Environmental impacts.A hydrological and a one dimensional hydraulic model of the Vaisigano River hasFlood management Action Plan 2007 16

een set up using the HEC-HMS and HEC-RAS software produced by the US ArmyCorps of Engineers.The hydrological model has been used to assess the following:o Flood flow hydrograph shapes.o Estimate peak flood flows.o The time it takes water to travel from the upper part of the catchment to the lowerpart.The hydraulic model covers the lower Vaisigano River from the Vaisigano Bridge atBeach Road to just upstream of Lelata Bridge a distance of approximately 2 km. Themodel was based on 32 surveyed cross-sections. Further details of the hydrologicaland hydraulic model consult the EU EDF 8 – SOPAC Project Report No : ER0069aIt is important to recognise that there is a vary high degree of uncertainty in carryingout hydrological estimates in Samoa, not just for flood management, but also forwater quality assessments, water resources management, sanitation and watersupply projects.The work carried out by SOPAC/EU project in July 2006 indicated that the 1 in 100year flood flow for the Vaisigano River at Apia is likely to be between 400 m 3 /s and600 m 3 /s. For consistency the flood flows that have been used to asses the variousstructural flood mitigation options are those produced by Kellogg, Brown and Root forthe Asian Development Bank Technical Assistance (TA) project 4229-SAM:Institutional Strengthening for Drainage and Wastewater Management which is beingimplemented by the Planning and Urban Management Authority (PUMA).The design flood flows adopted for this plan for the lower Vaisigano River at Apia aredetailed in Table 3-1.Table 3-1: Design flood flows for the Lower Vaisigano at ApiaReturn period(years)Annualprobability ofoccurrence (%)Design flood flows for the lower VaisiganoRiver at Apia(m 3 /s)1 in 2 50 1741 in 5 20 2831 in 20 5 4181 in 50 2 4701 in 100 1 550Note: There is a high degree of uncertainty in these flood flow estimates3.2. Structural mitigation measuresThis section details a range of structural mitigation options and the actions that arerequired to take these forward. Before many of these structural mitigation optionscan be prioritised it is important to:(i)(ii)Improve the quality of data (e.g. hydrological, topographical).Assess the cost and benefits for each of the options.Flood management Action Plan 2007 17

3.2.1. Flood embankments and wallsFlood embankments and walls can provide an effective way to protect existingdevelopment in flood-prone areas. The height or crest level of the flood walls orembankment is determined by factors that include:o Flood levels.o Required standard of protection.o Economics. This is defined by the way in which the project is appraised, forexample this is usually carried out via a cost-benefit analysis.o Physical limitations of the site. Flood walls are normally used in restrictedlocations.The difference between a flood wall and a flood embankment is shown in Figure 2-2and Figure 3-1Figure 3-1: Example of a cross-section through a typical flood defence embankmentThere is a risk that embankments and walls may fail, and there is an ongoing needfor maintenance and repair. In addition, embankments and walls will be overtoppedduring events exceeding their design standard.Using the hydraulic model for the Lower Vaisigano River an initial estimate of theheight of a flood embankment/wall for various return period floods in the downstreamreach of the lower Vaisigano has been considered. The construction of floodembankments/walls has been considered in the reach between the Leone andVaisigano (Beach Road) Bridges, a reach of approximately 900 m. This is becausethis reach of the Vaisigano River has the highest number of elements at risk in termsof people and properties. The proposed location of the flood embankments is shownin Figure 3-2.Flood management Action Plan 2007 18

Location of floodembankmentsFigure 3-2: Location of flood embankments for the lower Vaisigano River downstreamof Leone BridgeThe height of the flood embankment has been estimated using the steady state HEC-RAS hydraulic model of the lower Vaisigano River. It should be noted that the heightof the embankment/flood wall will vary depending on the height of the left and rightbank of the river. Table 3-2 provides details of the average height of the floodembankment/walls and the maximum height of the flood wall for the left and the rightbanks of the river.Table 3-2 does not contain any allowance for “freeboard”. Freeboard is the heightabove a defined flood level typically used to provide “a factor of safety” for settingembankment crest levels. This “factor of safety” is used to take account ofuncertainties in the hydrological and hydraulic calculations and other factors such assettlement. To protect the lower portion of the catchment against the 1 in 100 yearflood the average height of the left bank and right bank embankments would have tobe 3.24 m and 2.81 m respectively.Flood management Action Plan 2007 19

Table 3-2: Summary of embankment/wall heightsReturn period(years)Average height of theembankment (m)Maximum height ofembankment (m)Left bank Right bank Left bank Right bank1 in 2 0.96 0.61 1.72 1.371 in 5 1.72 1.35 2.60 2.181 in 20 2.54 2.13 3.51 2.971 in 50 2.83 2.40 3.82 3.231 in 100 3.24 2.81 4.29 3.62Note: There is no allowance for freeboard in these figuresTable 3-3 provides an initial estimate of the amount of material required to constructthe flood embankments has been made. It has been assumed that the crest width ofthe embankments would be 2 m and that they would have 1 in 2 side slopes. Across-section through the embankments is shown in Figure 3-3. To construct floodembankments to protect the lower reaches of the Vaisigano floodplain against the 1in 100-year flood approximately 26,400 m 3 of material would be required. Thisvolume of fill does not take into account any allowance for freeboard.Table 3-3: Summary of the preliminary volume of fill material required for the floodembankments in the lower Vaisigano RiverReturn period(years)Amount of fill material required (m 3 )Left bank Right bank Total1 in 2 2,650 1,500 4,1501 in 5 5,800 4,050 9,8501 in 20 10,150 7,750 17,9001 in 50 11,900 9,250 21,1501 in 100 14,700 11,700 26,400122 m21122 m21Figure 3-3: Cross-section through the flood embankments for the Lower Vaisiganodownstream of Leone BridgeFlood management Action Plan 2007 20

Table 3-4 provides an estimate of the number of buildings and people that could beprotected by the construction of an embankment or wall between Leone and theVaisigano Bridges.Table 3-4: Number of people and properties protected by building an embankment orwall between the Leone and Vaisigano BridgesReturn period(years)Number of peopleprotected1 in 2 1125 2411 in 5 1270 2721 in 20 1330 2851 in 50 1330 2851 in 100 1363 292Number of buildingsprotectedRecommended Actions:To further investigate the feasibility of flood embankments/walls as a flood mitigationoption it is recommended that the following actions should be carried out:o Improve the accuracy of the topographic and hydrological data available for thelower Vaisigano River and its floodplain in order to reduce the uncertainty in thedesign flood levels.o Establish the availability of material to construct such an embankment/wall andalso the need for a “cut-off” to prevent seepage underneath the protection.o Make a preliminary assessment of the costs of constructing and maintaining floodwalls/embankments.o Quantify the economic benefits that are derived by building a floodembankment/wall for a number of return periods.o Establish if the bridge across the Vaisigano River at Beach Road would have tobe modified to allow flood flows to pass under it without any damage occurring.o Assess land ownership issues in the Lower Vaisigano and establish whetherthere is sufficient space to construct a flood wall/embankment along the banks ofthe river.o Make an assessment of the local runoff that may collect behind the floodwalls/embankments. This needs to be taken into account. Pumps may berequired to remove this water during a flood event. If these pumps fail then localflooding behind the flood walls embankments may still occur in the protectedarea.o Establish the views of the local communities along the length of the river.o Make a preliminary assessment of the environmental impacts including the visualimpacts of constructing this option.3.2.2. Flood storageA flood storage basin is an artificial reservoir specifically designed for the temporarystorage of excess floodwater, thus limiting the flow that passes downstream.Floodwater is released gradually after the flood has passed. A flood storagereservoir requires controls to limit the amount of water passing downstream. Floodstorage basins may be classified as “on-line”, where the river channel passesthrough the storage area, and “off-line”, where the river channel bypasses thestorage area.In the Vaisigano River catchment the amount of space in the floodplain for off-linestorage is very limited owing to the topography and nature of the river’s floodplain.However, there is a possibility of providing on-line storage in the upstream part of theFlood management Action Plan 2007 21

catchment. The approximate location for the storage is shown in Figure 3-4. Theprovision of on-line flood storage would require the construction of an embankmentdam. A typical section through an earth embankment dam is shown in Figure 3-5.Using the flood flow hydrographs developed for the Lower Vaisigano River apreliminary estimate of the minimum storage volume required for such a structurehave been made.Using the one-dimensional hydraulic model of the Vaisigano River the bankfullcapacity of the lower reaches of the Vaisigano River has been estimated to beapproximately 100 m 3 /s. The bankfull capacity of river is the flow that it can carrywithout the water level exceeding the levels of the bank. Hence in order to reducefluvial flooding from the Vaisigano in Apia the on-line storage should be sized suchthat the peak of the flood flow hydrograph is attenuated to 100 m 3 /s. The minimumstorage volumes required to attenuate a three hour duration hydrograph to 100 m 3 /sfor different return periods is given in Table 3-5. The assumptions made in thesecalculations are shown illustratively in Figure 3-6.Table 3-5: Preliminary storage volumes and heights required for an on-line storagedams for flood storage 4Return period(years)Volume of flood storage(million m 3 )Indicative height of aflood storage dam(m)1 in 2 0.4 181 in 5 1.2 261 in 20 2.3 321 in 50 2.8 351 in 100 3.4 37An initial estimate has been made of the minimum height of the dam required. Itshould be noted that there was insufficient topographic data available in the uppercatchment to estimate the dam height accurately. The dam heights for the variousreturn periods have been assessed from a simple geometric relationship betweenreservoir volume and river slope. As a consequence the heights in Table 3-5 arevery preliminary and have a high degree of uncertainty attached to them.For this option to be cost effective it is likely that the flood storage reservoir wouldhave to fulfil a number of purposes. For example it could also be used as a source ofwater supply and hydropower. It is important to note that the figures provided inTable 3-5 are only indicative and only include the volume required from a floodstorage point of view. Should a multipurpose reservoir be considered, the volume ofstorage required would need to be increased to cater for these other functions. Thenumber of people and properties that would be protected by the construction of anearth embankment dam is given in Table 3-6.4 Note: These values are preliminary. They are based on a three hour duration hydrograph and thatthe bankfull flow of the lower Vaisigano River is approximately 100 m 3 /s. There was no detailedtopographic data available in this area.Flood management Action Plan 2007 22

Table 3-6:Return period(years)Number of people and properties protected by building an embankmentdam in the upstream reaches of the catchment 5Number of peopleprotected1 in 2 1139 2441 in 5 1382 2961 in 20 1536 3291 in 50 1596 3421 in 100 1634 350The following should be noted with respect to this option:Number of buildingsprotectedo A flood storage reservoir would require a substantial area of land to achieve thenecessary storage. However, the area where the storage reservoir is located isnot densely populated and is understood to be a Government reserveo Long duration or multi-peak storms, where the reservoir is partly or completelyfilled from a previous flood peak, can reduce the effectiveness of this mitigationoption. Once the reservoir is full, attenuation of the flood discharge is small.o When the reservoir is full, overtopping will occur and if the storage dam is notdesigned correctly there is a risk of breaching and this resulting in significantdownstream hazard.o The flood storage basins may trap sediment, and require regular maintenance forsediment removal. There may also be adverse impacts downstream associatedwith this loss of sediment.ApiaHarbour0 kmVaisiganocatchmentboundary5 kmPossible locationof an upstream floodstorage reservoirFigure 3-4: Indicative location for upstream flood storage5 Note: These numbers are an underestimate of the total number of people and property protectedbecause it does not take account of the elements at risk upstream of Lelata Bridge. This is becausethere is no flood hazard mapping available for the catchment upstream of this point.Flood management Action Plan 2007 23

Clay coreFill materialUpstreamDownstreamCut offFigure 3-5: Cross-section through a typical earth embankment dam600Flow (m 3 /s)500400300Estimate of thevolume of on-linestorage requiredAmount ofattenuationrequired200100Bankfull flow for the lowerVaisigano River00 5 10 15 20 25 30Time (hours)Figure 3-6:Illustration of the estimation of flood storage for the 1 in 100 year floodhydrographRecommended actions:To further investigate the feasibility of constructing an on-line flood mitigation optionsit is recommended that the following actions should be carried out:o Improve the accuracy of the topographic and hydrological data available for thelower Vaisigano River and also in the area where the on-line flood storage couldbe constructed. This is the key to establishing the volume of the flood storagereservoir and the height of the dam required.o Assess the probable maximum flood for the flood storage reservoir and producean estimate of the required spillway capacity.Flood management Action Plan 2007 24

o Estimate the volume of the fill required to construct an embankment dam.o Make a preliminary assessment of the costs of constructing and maintaining floodstorage.o Quantify the economic benefits that are derived by constructing a storage dam fora number of return periods.o Assess land ownership issues in the area where the reservoir would beconstructed.o Make a preliminary assessment of the environmental impacts including the visualimpacts of constructing this optiono A preliminary assessment of the effect of a dam breach on the population livingdownstream of the storage should be made.3.2.3. By-pass or diversion channelBypass or diversion channels redirect a portion of flood flow away from areas at risk,and reduce flood levels along the channel downstream of the diversion off take.Opportunities for the construction of diversion channels are often limited by thetopography of the area, ecological considerations and the availability of land. Apossible route for a flood diversion channel is shown in Figure 3-7. The off take forthe diversion channel would be located in the vicinity of Lelata Bridge. The channelwould run in a north-easterly direction before joining an existing river channel to thesouth of the Apia Park sports stadium. The length of the channel would be between1.5 km and 2 km depending on the route that was taken. The construction of such achannel would entail the construction of one new road crossing and the increase incapacity of another crossing on the main road to the east of the Apia Park sportsstadium.A very preliminary estimate of the size of the channel has been made using the HEC-RAS modelling software. It has been assumed that the channel would be trapezoidalin shape with a bed width of 30 m and 1 in 2 side slopes. The bankfull capacity ofthe Vaisigano River has been estimated to be some 100 m 3 /s. It has been assumedthat all flows greater than this are diverted into the bypass channel. A cross-sectionfor the assumed by-pass channel is shown in Figure 3-8. Table 3-7 provides detailsof the channels dimensions for a number of design period flood flows. It should benoted in the low lying area to the west of Apia Park stadium there may need to beflood defence embankments along the side of the channel to avoid the water spillingout of the channel and exacerbating flooding in this area.Recommended actions:To further investigate the feasibility of constructing an on-line flood mitigation optionsit is recommended that the following actions should be carried out:o Improve the accuracy of the topographic and hydrological data available for thelower Vaisigano River and for the route of the diversion channel. This is the keyto establishing the route of the channel and the amount of material that would tobe removed.o Assess the nature of the off take structure for the channel (e.g. gate, side spillweir).o Estimate volume of material that would need to be dredged from the existingdrainage channel that the by-pass channel would join.o Make a preliminary assessment of the costs of constructing and maintaining thediversion channel.o Quantify the economic benefits that are derived by constructing a diversionchannel for a number of return periods.o Assess land ownership issues in the area where the reservoir would beFlood management Action Plan 2007 25

constructed.o Make a preliminary assessment of the environmental impacts including the visualimpacts and health and safety of constructing this option.Figure 3-7: Possible route for a flood diversion channelTop width of channel varies dependingon the flow to be carried221130 mFigure 3-8: Cross-section of a possible flood diversion channel for the lower VaisiganoRiverFlood management Action Plan 2007 26

Table 3-7:Returnperiod(years)Preliminary dimensions of a flood diversion channel for the LowerVaisigano 6Capacity of thechannel(m 3 /s)Depth of channel(m)Top width of channel(m)1 in 2 74 0.9 33.61 in 5 183 2.0 38.01 in 20 318 2.1 38.41 in 50 370 2.4 39.61 in 100 450 2.7 40.83.2.4. Increasing channel conveyanceThe capacity of a river channel to discharge floodwater can be increased bywidening, deepening or realigning the channel, and by clearing the channel banksand bed of obstructions to flow. Such “improvements” can increase the velocity andpossibly the depth of flow. A particular example of a method of increasing theconveyance capacity providing enhancement opportunities is the creation of a “twostage” channel. In this case the existing river channel is retained for low and mediumflows, and floodplains are created parallel to the river channel to accommodate floodflows.Increasing the channel conveyance capacity can, like diversion channels, reduceflood attenuation and increase the flood risk downstream. Other disadvantagesinclude the cost of maintenance of oversized channels, where sediment depositionmay occur.A preliminary investigation into increasing of the channel capacity has indicated thatthe Vaisigano River would have to be widened by some 70 m at the downstream endwith the bed level dredged to -1 m below mean sea level. At the upstream end nearLeone Bridge the channel needs to be widened by 50 m to prevent flooding duringthe 1 in 100 year flood. The widening and dredging of the channel upstream ofLeone Bridge has not been considered because this part of the Vaisigano River isconstrained by bed rock meaning that the costs of channel widening and dredgingare likely to be prohibitive.The key disadvantages of the increase in channel conveyance for the lowerVaisigano are as follows:o The issue of land tenure and the socio-economic cost and impacts of relocatingcommunities that live adjacent to the Vaisigano between Leone and VaisiganoBridges.o The cost of maintenance of the oversized channels, where sediment deposition islikely to occur.o The destruction of riparian habitat and the visual impact of replacing naturallyvarying channel sections with a section of more uniform geometry.6 Note: The channel is assumed to be trapezoidal with 1 in 2 side slopes and a bottom width of 30 mNo allowance for freeboard has been made when estimating the depth of the channelFlood management Action Plan 2007 27

Recommended actions:If increasing the channel conveyance of the lower Vaisigano River was to beconsidered in more detail then the following actions would be required:o Improve the accuracy of the topographic and hydrological data available for thelower Vaisigano River and its floodplain in order to reduce the uncertainty in thedesign flood levels.o Establish the quantity of cut that would need to removed to widen and deepen theLower Vaisigano to prevent flooding for a number of design return periods.o Make a preliminary assessment of the costs of increasing the conveyance of thelower Vaisigano.o Quantify the economic benefits that are derived by increasing the conveyance ofthe lower Vaisigano for a number of return periods.o Assess land ownership issues in the Lower Vaisigano and establish the cost ofrelocation of communities adjacent to the river.o Assess the sediment load in the river and quantify the amount of material thatwould have to be dredged from the river in order to maintain the new channelprofile and cross-section.o Make a preliminary assessment of the environmental impacts including the visualimpacts of constructing this option3.2.5. PumpingPumping is an effective flood mitigation measure for relatively small catchments (e.g.in Samoa this probably means less than 1 km 2 ) where the flood volumes are not toogreat. However, in the case of the Lower Vaisigano where the flows are high (e.g.the 1 in 2 year flow is 174 m 3 /s), pumping is not a practical option owing to the size ofpumps required to lift such large volumes of water. The capital, and operation andmaintenance costs of pumps would be prohibitively high.3.2.6. River maintenanceRiver maintenance is used to reduce flood risk by a number of measures including:o Dredging.o Vegetation cutting.o Bank clearance.o Removal of obstructions and rubbish that may block structures such as bridges.The HEC-RAS hydraulic model of the Vaisigano River has shown that dredging thelower reaches of the river downstream of Leone Bridge by up to 2 m would only havea minimal effect on the depth of water in the floodplain. The same is true of cuttingvegetation and bank clearance. The Manning’s n roughness coefficient is currentlyset at 0.035 in the hydraulic model. Assuming that the weed cutting and bankclearance reduces this roughness coefficient to 0.025 then the 1 in 100 year floodwater level in the lower Vaisigano will only drop by some 0.22 m. This will provide aminimal amount of benefit to the elements at risk from flooding. In practice it isunlikely that the cutting vegetation and clearing the banks will reduce the roughnesscoefficient to 0.025. The removal of obstacles and rubbish that may block bridgeswould be a useful exercise but again is unlikely to have a significant effect on peakflood water levels.Flood management Action Plan 2007 28

Recommended actions:o A detailed assessment as to whether incentives can be found for riversidecommunities to carry out the maintenance of the river side vegetation.o An assessment of the tangible effects of carrying out improved maintenancealong the lower Vaisigano River.3.2.7. Flood proofing of buildingsFlood proofing refers to:o The design and construction of buildings with appropriate water-resistantmaterials such that flood damage to the structure of the building and contents isminimised when the building is flooded.o Increased ground floor levels.o The use of temporary barriers and other measures to reduce flood damage whena flood actually occurs.Flood proofing may be applied to both new construction and existing buildings. Inareas of the Lower Vaisigano River catchment that flood regularly where residentsare aware of the impacts, some buildings are already “flood proofed” using suchmeasures as stone and concrete floors and walls, raised floors and raised electricitysupply. The decision to adopt flood proofing as a formal mitigation measure is bestmade within the framework of a building control policy and land use plans.Furthermore, the Government of Samoa should raise awareness on pay-offs of floodproofing and create incentives to owners of existing buildings. Although floodproofing can reduce damage to flood-affected buildings, the occupiers still suffer thesocial disruption of flooding. In areas of the lower Vaisigano River where the flooddepths are high (i.e. greater than 1 m) it should be ensured that the residents can beevacuated from their property safely.Issues to consider in flood proofing the structure of a building include:o Raising floor levels above a recommended design flood level.o Design to withstand water immersion, differential water pressure on walls, debrisand flotation forces.o Use of methods of construction and certain types of materials which are betterable to withstand immersion than others. For example bricks and plastics aremuch better than many other materials and can withstand immersion withoutdamage and only require cleaning when the flood subsides.o Impact of polluted water, particularly by sewage from urban flooding.The most effective flood proofing measure is to raise the floor level above flood level.However, this involves additional cost in raising ground levels which can be verysignificant, particularly for large commercial buildings. Raised floor levels can alsoreduce the amount of available flood plain storage as water which would otherwiseflood buildings is now unable to do so. This must be taken into account in the overallassessment of the impact of the development on flooding. One method to preservethe floodplain storage is construct buildings on stilts. However, if this approach isadopted then it is important that the storage under buildings is not used for storage orfilled with rubbish.Flood management Action Plan 2007 29

Recommended actions:o Develop control measures for new developments. For example with regards to aminimum floor level a decision has to made by the Government of Samoaconcerning what return period (annual probability) flood above which floorsshould be raised and the amount floors should be raised above this level. Forexample a development control policy may be to have the minimum floor levels ofnew buildings to be a minimum of 300 mm above the 1 in 50 year flood level.o Provide advice on flood resistant construction materials.o Provide a mechanism by which the above measures are implemented in theconsenting procedure for new developments.o Provide advocacy on long-term pay-offs of flood proofing and create incentivesfor owners to invest in these proactive measures3.3. Non-structural mitigation measure optionsThis section details a range of non-structural mitigation options and the actions thatare required to take these forward.3.3.1. Development controlDevelopment control is concerned with whether or not developments should beconstructed in flood risk areas and, where developments are permitted, theconditions attached to the development. Such controls are aimed at reducing the riskof buildings and other assets being flooded, reducing the resulting damage whenabove floor flooding occurs, and avoiding increases in flood risk elsewhere.Typical development control requirements include for example, identification of theparts of a site where building may and may not be permitted, and minimum floorlevels. Careful and creative strategic site planning can reduce hazard and facilitateevacuation when required.It is recommended that PUMA and the Water Resources Division should statespecific requirements related to developments in flood prone areas and the type ofadditional data and analysis that might be required before developments are allowedin the floodplain. These requirements may include:o The assessment of the impacts of the development on flood levels elsewhere.o Specific comments on the proposed development to minimise the impact offloods.o Identification of suitable evacuation routes.o Environmental requirements.The safety of people during a flood event is of fundamental importance in thedevelopment of flood risk areas. Evacuation can be very hazardous if safeevacuation routes are not available. It is recommended that new developments in thelower Vaisigano River floodplain should either include safe locations for people, forexample in the upper floors of buildings, and/or safe evacuation routes. Provisionsfor the safety of people during floods should be agreed with the DisasterManagement Office and emergency services such as the police and the fire service.Flood maps have been produced showing the flood depth for the Lower Vaisigano fora number of return periods. The 1 in 20 and 1in 100 year maps showing the depth offlooding for these design floods are shown in Figure 3-9 and Figure 3-10respectively.Flood management Action Plan 2007 30

Figure 3-9: Flood depth map for the 1 in 20 year flood for the lower VaisiganoFlood management Action Plan 2007 31

Figure 3-10: Flood depth map for the 1 in 100 year flood for the lower VaisiganoFlood hazard varies significantly across the lower Vaisigano floodplain mainlybecause of topography. For example in the higher areas further away from the riverthe depth of flooding is generally lower than closer to the river as are flow velocities.By locating buildings in the higher parts of the site, their effect on flooding will bereduced, potential flood damage will be lessened and risks to people will be less.Flood management Action Plan 2007 32

The degree of flood hazard to people has been evaluated by assessing the productof the floodwater depth and water velocity, (i.e. water depth x water velocity). Thedegree of hazard is based on research related to the risk to people in floodwater.Table 3-8 shows the guidance on the degree of flood hazard for the lower Vaisigano.Flood hazard maps have been produced for the lower Vaisiagano. Figure 3-11 andFigure 3-12 show the flood hazard map for the 1 in 20and 1 in 100 year floods for theVaisigano respectively based on the degree of flood hazard shown in Table 4.8.Table 3-8: Guidance on the degree of flood hazardFloodwater depth(m) xwater velocity (m/s)(m 2 /s)Degree offloodhazardDescriptionLess than 0.75 Low CautionFlood zone with shallow flowing water or deepstanding water0.75 to 1.25 Moderate Dangerous for some (i.e. children)Danger: Flood zone with deep or fast flowingwater1.25 to 2.5 Significant Dangerous for most peopleDanger: Flood zone with deep fast flowingwaterGreater than 2.5 Extreme Dangerous for allExtreme danger: Flood zone with deep fastflowing waterFlood management Action Plan 2007 33

Figure 3-11: Flood hazard map for the 1 in 20 year flood for the lower VaisiganoFlood management Action Plan 2007 34

Figure 3-12: Flood hazard map for the 1 in 100 year flood for the lower VaisiganoThe flood depth and flood hazard maps presented in Figure 3-9 to Figure 3-12 arebased on the results of the one-dimensional hydraulic model of the lower Vaisigano.It should be noted that there is a high degree of uncertainty in the flood water depthsand hazard zones for the following reasons:Flood management Action Plan 2007 35

o There is a high degree of uncertainty in the design flood flows owing to the lack ofhydrological data.o There was limited calibration of the hydraulic model as the result of limitedinformation on historical floodwater levels and flows.o The HEC-RAS hydraulic model of the Vaisigano is only one dimensional meaningthat only an average value of velocity in the floodplain can be estimated at eachcross-section.o There is an uncertainty in the vertical resolution of the digital terrain model of thelower Vaisigano that was used to estimate the flood extents and the flood depths.Recommended actions:The following actions should be carried out with regards to the flood extent andhazard maps:o Improve the accuracy of the topographic and hydrological data available for thelower Vaisigano River and its floodplain in order to reduce the uncertainty in thedesign flood levels.o Regularly update the hydraulic model using additional survey data, especiallyareas of the model where surveyed data is sparse.o Re-run the model every time flood flows are re-estimated.o Re-evaluate the flood extents and flood hazard for the design return periods.With regards to new developments the following actions should be undertaken:o Incorporate minimum floor level requirements in policy, regulations (e.g. buildingcodes) and legislation.o Enforce minimum floor level requirements for new development.o Produce floodplain risk reduction guidelines.3.3.2. Flood forecastingForecasting flood water levels several hours in advance is difficult in Samoa. This isbecause the catchments are steep, relatively small and rainfall events intense. As aresult floodplains can flood in a matter of hours. The flooding that occurs in the lowerVaisigano floodplain can be defined as flash flooding. Flash flooding is sudden andunexpected flooding caused by local heavy rainfall or rainfall in another area. Flashfloods are difficult to forecast accurately. However, it may be possible to issue flashflood warnings based on flash flood guidance estimates. These estimates areindices of the volume of rainfall of a given duration over the Vaisigano catchment thatis just enough to cause minor flooding at the downstream end of the river, which inthis case is a flow of around 100 m 3 /s to 150 m 3 /s. These indices would be used withestimated or forecast precipitation over the Vaisigano catchment to arrive at flashflood threat indices that form the basis of decisions regarding the dissemination ofwarnings. The dominant source of uncertainty in these decisions is the precipitation.In order to set up such a forecasting system the first step is for forecast precipitationdata to be available for the whole of the Vaisigano River catchment. We understandthat the there is an Australian forecasting model available that can forecast hourlyrainfall up to six hours in advance. In order to validate the flood forecasting guidancethere would also be a need to install more rainfall intensity gauges in the catchmentwith which to validate the model to understand the uncertainty in the forecast rainfall.There is also a need to validate the existing hydrological model so that it can be usedto assess what rainfall intensity pattern triggers flooding in the lower Vaisiganofloodplain.Flood management Action Plan 2007 36

Recommended actions:The following actions are required to set a flood forecasting system for the lowerVaisigano:o Investigate the availability and cost of obtaining forecast six hourly precipitationdata six hours in advance.o Assess the cost of installing three additional rainfall intensity gauges in theVaisigano catchment.o Calibrate the hydrological data using hydrological data collected over the nextthree years to reduce the uncertainty in the rainfall intensity that triggers flooding.o Collect data to reduce the errors in issuing false flood forecasts.o Assess how the flood forecasting process would be organised with the MNRE.o Assessing the benefits of setting up a flood forecasting system.It is recommended that Meteorology Division takes ownership of any floodforecasting model.3.3.3. Flood warningsIt is important that there is a method for disseminating flood warnings and that thereare different levels of flood warning that are well understood by the communities thatlive in flood prone areas. It is recommended that a method for disseminating theflood warning, other than just alerting the media, is set. The different levels of floodwarnings that are set up could be along the lines of the following:o Flood Watch: Flooding possible. Be aware! Be prepared! Watch out!o Flood Warning: Flooding expected affecting homes, businesses and main roads.Act now!o Severe Flood Warning: Severe flooding expected. Imminent danger to life andproperty. Act now!It should be noted that warning levels based on colours (e.g. green, yellow, red) areoften confusing for local communities.Recommended actions:The actions related to flood warning include:o Establishing a process for communities in flood prone areas receiving floodwarnings especially if a flood occurs in the middle of the night.o Develop a series of staged flood warnings.o Establish a process (e.g. an advertising campaign in the media) to ensure thatcommunities understand what each different warning means.3.3.4. Flood insuranceFrom our consultation with a private insurance company in Samoa we understandthat it is unlikely that residents and businesses in flood prone areas will be offeredinsurance against flooding. It is recommended that the insurance industry has agreater involvement in flood management in Samoa.Recommended actions:o Being consulted on guidelines for floodplain risk reduction.o Being consulted on major developments and working with local communities, theFlood management Action Plan 2007 37

Samoan Government and developers to develop schemes where the flood risk isacceptable to insurers.3.3.5. Improving flood preparedness and responseRecommended actions:Measures to increase the flood preparedness in flood prone areas should include:o Develop flood response planso Raising awareness of flood risk.o Flood warning arrangements and advice to communities, businesses and otherstakeholders on how they should respond.o Preparatory measures by communities and businesses to protect properties andcontents.o Arrangements for public safety including evacuation plans where required.These measures will reduce both the intangible as well as the tangible costs offlooding. One challenge is to maintain an adequate level of flood awareness duringextended periods when moderate to severe flooding does not occur. A continuingawareness programme must be put in place to inform new residents, maintain thelevel of awareness of old residents and to cater to changing circumstances of, forexample, flood behaviour and new developments should be put in place.The flood-prone communities must be made aware and remain aware of their role inthe overall floodplain management strategy for their area, including the evacuation ofthemselves (and possibly personal goods and possessions). Sustaining anappropriate level of flood awareness will involves a continuous effort by variousSamoan Government Departments, community groups and the emergency services.The cost of maintaining a level of awareness should be budgeted for. It should benoted that irrespective of the available warning time, generally there is widespreadvariation in flood awareness, both between households and communities.3.3.6. Land use changeRural land use changeRural land use change (e.g. the afforestation of catchments) is often put forward as amethod of reducing flood flows. The upper Vaisigano catchment, which forms themajority of the drainage area, remains largely covered in trees. Forests interceptprecipitation, and this has sometimes led to the misconception that forests can“absorb” floods, acting like a sponge. In the case of a flood-producing rainstorm overthe Vaisigano catchment, only a limited amount of rainfall (typically up to 5 mm to 10mm) is intercepted which will not in itself have a significant mitigating impact onreducing flood flows. It can thus be concluded that adjusting the rural land use willnot have a significant effect on reducing downstream flood risk 7 .Increasing urbanisation of the catchmentWith respect to urban land use change, the development of houses and businessesin the catchment will increase the impervious area and will often result in a localincrease in flood flows. It is recommended that PUMA puts in place in its consenting7 Forest has very minimum impact on flood controlFlood management Action Plan 2007 38

process guidance through which the runoff from new developments is controlled sothat it does not increase the downstream flood risk.3.4. Summary of actions that are requiredIt can be concluded that the following mitigation measures will not significantlyreduce flood levels in the lower Vaisigano River catchment:o Pumping.o Rural land use change.o Improved river maintenance.Although improved river maintenance has been shown to reduce the 1 in 100 year bysome 0.22 m at best it is important that this option is considered in more detail. Thisis because improved river maintenance may lead to less debris being carried in theriver and thus reduce the potential for structures to become blocked. It will alsoreduce the risk to life by reducing the possibility of people being struck by objects inthe floodwater. Hence although improved river maintenance does not significantlyreduce the floodwater levels it is important to pursue this action.The actions that need to be carried out for structural mitigation options aresummarised in Table 3-9. The actions that need to be carried out for non-structuralmitigation options are summarised in Table 3-10.Flood management Action Plan 2007 39

Table 3-9: Actions required for structural mitigation measuresActionImprove the hydrological and meteorologicalnetwork, and the collection and archiving ofdata in the Vaisigano River catchmentReduce the uncertainty in the flood flowestimates for the lower Vaisigano via thefollowing:Collecting high flow data and rainfallintensity data for the Vaisigano catchmentduring future floodsUsing the hydraulic model toReduce the uncertainty in the hydraulicmodel of the lower Vaisigano River by thefollowing:o Calibrating using flow data and waterlevel data collected during future floodso Introducing more surveyed crosssectionsinto the model especially inareas where topographic data is sparseCollect detailed topographic data at thelocation(s) where the mitigations are to beemployedAssess land ownership issuesAssess capital, operation and maintenancecostsEstablish the geo-morphological impactsAssess the environmental impacts of themitigation measuresAssess the direct economic and socialbenefits of the measure of a range of returnperiods to assess the average annualdamage and benefitsProvide advice on flood resistantconstruction materialsProvide a mechanism by which the aboveflood resistant materials are implemented viathe consenting procedure for newdevelopmentsStructural mitigation measuresthat the action applies toFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceImproving the channel maintenanceFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceImproving the channel maintenanceFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceFlood walls and embankmentsUpstream flood storageBy-pass channelFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceImproving the channel maintenanceFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceFlood walls and embankmentsUpstream flood storageBy-pass channelIncreasing the channel conveyanceFlood walls and embankmentsUpstream flood storageBy-pass channelFlood proofing of new buildingsFlood management Action Plan 2007 40

Table 3-10: Actions required for non-structural mitigation measuresAction Non-structural mitigationmeasures that the action applies to• Improve the accuracy of the topographicand hydrological data available for thelower Vaisigano River and its floodplainFlood extent, flood depth and floodhazard maps for the lower Vaisiganofloodplainin order to reduce the uncertainty in thedesign flood levels.• Regularly update the hydraulic modelusing additional survey data, especiallyareas of the model where surveyed datais sparse.• Re-run the model every time flood flowsare re-estimated• Re-evaluate the flood extents and floodhazard for the design return periods• Incorporate minimum floor level Development control proceduresrequirements in policy, regulations (e.g.building codes) and legislation• Enforce minimum floor levelrequirements for new development• Produce floodplain risk reductionguidelines• Investigate the availability and cost ofobtaining forecast six hourly precipitationdata six hours in advance• Assess the cost of installing threeadditional rainfall intensity gauges in theVaisigano catchment• Calibrate the hydrological data usinghydrological data collected over the nextthree years to reduce the uncertainty inthe rainfall intensity that triggers flooding• Collect data to reduce the errors inissuing false flood forecasts• Assessing the benefits of setting up aflood forecasting system• Establishing a process for communitiesin the lower Vaisigano River catchmentreceiving flood warnings especially if aflood occurs in the middle of the night• Develop a series of staged floodwarnings• Establish a process (e.g. an advertisingcampaign in the media) to ensure thatcommunities understand what eachdifferent warning means• Maintain the awareness of flooding viaawareness campaigns in the media andeducation within the schooling systemFlood forecasting for the lowerVaisigano catchmentFlood warning for the lower VaisiganocatchmentFlood preparednessFlood management Action Plan 2007 41

4. Flood Management Action Plan MatrixGOAL 1: FLOOD RISK REDUCTIONOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE1. Appropriatestructural mitigationoptions based onsocial, economic andenvironmental factorsDefine a effective andclear planning process fordetermining the mostappropriate floodmitigation optionsAssess and implementprioritised structuralmitigationoptions to reduce floodheight related to eachreturn period and hazardzoneDraft and applymaintenance plan forimplemented structuralmitigation measuresInformed decisionmaking on which arethe most appropriateoptions to reduce floodriskStructural mitigationprioritised andimplementedRange of appropriateflood mitigation optionsidentifiedNumber of structuralmitigation prioritiesplanned and constructedand flood risk reducedRESPONSIBLEAGENCIES 8• TARGET 9AGENCIES2007 MNRE-WRDMNRE-PUMAInfrastructure Division(MWTI)• DMO• Environment andConservation• Land ManagementDivision2007- 08 forassessing andprioritising tobe followed byconstructionwhen fundsare secured by2010.Draft 2007-08ApplicationOngoingAsset managementRoads Division (MWTI)• MNRE-PUMA• MNRE-WRD• Insurance• MWCSD• MOF8 Responsible agency or agencies refer to the organization(s) responsible for initiating and making sure that the ‘actions’ are carried out/implemented.9 Target agency or agencies are the agencies that should be consulted and involved in the planning and implementation of the ‘action’Flood management Action Plan 2007 42

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE2. Improvedevelopment control toaddress flood riskreductionIncorporate minimum floorlevel requirements fordevelopment controlbased on water levelsmodelled for specifiedreturn period and for eachfloodplain andAgreed requirementsfor minimum floor levelabove specified returnperiod (annualprobability of flooding)incorporated intodevelopment controlprocess for all newdevelopmentEnforced developmentguidelines and buildingcode amendedRESPONSIBLEAGENCIES 8• TARGET 9AGENCIES2007 MNRE-WRDMNRE-PUMAMWTI-Building Division• DevelopersDevelop a guideline fordevelopment control infloodplainCreate awarenessprogrammes on necessityof minimum floor levelsand development controlin flood prone areasProduce a flood-returndesign standard forinfrastructuraldevelopmentEffective and clearprocess fordevelopment approvalin floodplainsRelevant stakeholders,e.g. developers andurban communities areaware of flooddevelopment controland its benefits and actaccordinglyDevelopers andcommunities implementthe approved floodreturndesign standardsfor infrastructural andurban drainagedevelopmentGuideline endorsed byCabinetNumber of new/existingdevelopment constructed/retrofitted with minimumfloor levelsFlood design standardapprovedEnd of 2007Start 2007,ongoingMNRE-PUMA• DevelopersMNRE-PUMAMNRE-WRDMNRE-DMOMWTI-Building divisionNGOs• Private Sector2009 MWTIMNRE-PUMAMNRE-WRD• SWA• EPC• Developers• Other utilitiesFlood management Action Plan 2007 43

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE3. Amend existingBuilding Code toaddress flood riskreductionReview and incorporateminimum floor levelrequirements into buildingcode for new developmentin flood prone areasMinimum floor levelrequirements forbuildings constructedused by developersRevised building codeincorporating minimumfloor level requirementsavailable and usedRESPONSIBLEAGENCIES 8• TARGET 9AGENCIES2007-08 MWTI-Building DivisionMNRE-PUMA• Developers• IPES4. Improvement ofexisting Infrastructureto reduce flood risk5. Strengthencommunities and/orhouseholds capacity inflood risk reductionAssess and upgradeexisting urban drainageand infrastructuralcapacityAdvocate suitablemitigation options forcommunities/ household atriskImprove communityprogramme 10 to includechannel maintenanceCapacity of urbandrainage, roads,bridges and utilitiesupgrading plan to copewith flood-return designstandard approvedIncreased resilience ofcommunities andhouseholds to floodingProactive communityparticipation in channelmaintenanceProject concept andproposal document for theupgrading of urbandrainage, roads, bridgesand utilities completedand implementedReduced losses to life,livelihood and propertyand less people affectedby floodLevel of communityresponse/involvementsupported by relevantagencies2012 MWTI-Road DivisionMNRE-PUMA• MNRE-WRD• EPC• SWA• Other utilitiesOngoing MNRE-DMOMNRE-WRDMNRE-PUMAMWCSDNGOsPrivate sector• communityOngoing STAMNRE-WRDNGOsMWCSD (VillageMayor)Asset management(MWTI)• community10 Community programmes such as the Samoa Tourism Authority Programmes and Environment WeekFlood management Action Plan 2007 44

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATEEncourage/promotepublic-private sectorpartnership to developfinancing schemes forflood management andcreate incentives for floodproofing of buildingsFinancial mechanismsavailable for flood riskreductionNumber of fundedschemes to reduce floodriskOngoingRESPONSIBLEAGENCIES 8• TARGET 9AGENCIESMWCSDMOF (small schemefinancing)MNRE-DMONGOsFinancing institutesPrivate sector• communityFlood management Action Plan 2007 45

GOAL 2 : FLOOD PREPAREDNESS AND EARLY WARNINGOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE6. Improved awarenessand knowledge of floodrisk management andrelated flood issues7. Strengthen floodforecastingDevelop appropriatecommunity floodawareness programmes 11Develop and incorporateflood risk management intoschool curriculaStrengthen technicalcapacity for developingand managing a floodforecasting systemReview the requirementsand benefits rainfall/runoffforecasting modelsFunded awarenessprogrammeimplemented andrelevant materialproduced anddisseminatedStudents level ofknowledge andawareness of floodrelated issuesincreasedCapacity to accuratelyforecast and releasepredicted water level toofficial contact points asrequired by the SamoaNational DisasterMaster PlanRainfall and flowprediction modelsproduced and updatedfrom hourly rainfall dataIncreased level of floodawarenessFlood risk managementtaught in schoolsAchieved minimum leadtimeRiver flows at Apiaforecast on an hourlybasisStart developingthe programmeand material in2007 and for theawarenessprogramme to beongoingStart consultingwith the Ministryof Educationearly 2007RESPONSIBLEAGENCIES• TARGETAGENCIESMNRE-DMOMNRE-WRDMNRE-PUMAMNRE-MeteorologyMNRE-TSDNGOsPrivate sector• communityMNRE-WRDMNRE-DMOMNRE-PUMAMESC2007-2008 MNRE-MeteorologyMNRE-WRD• MNRE-DMO• Media2007 review MNRE-MeteorologyMNRE-WRD11 Through active community participation and media – radio, TV advertisements; Posters/ Billboards; Printed documents; Games; Internet – flood maps onthe MapServer maps.meteorology.gov.ws; www.meterology.gov.ws; www.mnre.gov.ws; Use of flood marks on buildings; Disaster awareness week (nationalweek)Flood management Action Plan 2007 46

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE8. Improve FloodWarningReview and strengthenorganisationalarrangements for theoperation of the floodforecasting systemInstall telemetric waterlevels and rainfall datagauges within the relevantcatchmentReview and strengthenexisting early warningsystem to take intoaccount short lead time ofless than 2 hoursDevelop a multi-stagedwarning system for thepublicConduct public awarenesson the response to themulti-staged flood warningFlood forecastingsystem operational 24/7Availability of real-timedata for the floodforecasting systemCoordinated (floodforecasting and floodwarning) process inissuing accurate andtimely warningEffective Multi-stagedwarning available toagencies andcommunitiesIncreased awarenesson what each stage ofwarning means andhow to respondEffective process forflood forecastingNumber of telemetricstations and gaugesinstalledNumber of people andcommunity emergencyservices receiving andresponding to warningWarning systemunderstoodNumber of communityawarenessprogrammes and mockexercises completedRESPONSIBLEAGENCIES• TARGETAGENCIES2007 MNRE-WRDMNRE-MeteorologyMNRE-DMOInstalling to startin 2007MNRE-WRDMNRE-MeteorologyOngoing MNRE-MeteorologyMNRE-WRDMNRE-DMOMedia• Community2008 MNRE-MeteorologyMNRE-DMO• MNRE-WRD• MediaOngoing MNRE-DMOFire and emergencyservicesMedia• Community• Other responseagencies• NGOs• MOH• Red CrossFlood management Action Plan 2007 47

GOAL 3 : CAPACITY BUILDING IN FLOOD MANAGEMENTOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE9. To strengthenOrganisational Capacityin flood managementAssess and implementtraining needs for floodrisk managementProvide targeted formaltraining in hydrology,hydraulics, water resourcemanagement andmeteorologyInstitutionalise floodmodelling and mappingtrainingOn the job training orattachment with institutecarrying out floodmodellingUtilise the professionalvolunteer scheme 12 for awater engineerspecialising in flood riskmanagementKey Governmentagencies, emergenciesservices, privatesectors and NGOstraining needs for floodrisk reduction and floodmanagement identifiedCertified staff withappropriate skillsCourses delivered bytraining institutesAnalytical skills tomanage and interpretdata availableTechnical expertiseavailableKey capacity needsidentified and a trainingprogramme planavailableTraining needsassessment ofstart in 2007 andfor trainingopportunity to beavailable forsuitablecandidates forthe next 5 years.RESPONSIBLEAGENCIES• TARGET AGENCIESMNRE-MeteorologyMNRE-WRDMNRE-PUMASWAMWTI-Building DivisionMWTI-Road DivisionMOHUtilitiesNumber of staff trained Ongoing MNRE-MeteorologyMNRE-WRD• SWA• MWTI• MNRE-PUMAFlood modelling andmapping coursedeliveredNumber of attachmentopportunities andtraining programmesavailableVolunteer schemeidentified suitableexpertOngoingOngoingUSP, NUS• MNRE/TSDMNRE-MeteorologyMNRE-WRD• MNRE-PUMA2008 MNRE-WRD12 Professional volunteers schemes such as the JICA, Australia Youth Ambassador Programmes, UN Volunteers, Peace Corps and others considered appropriate by theGovernment of SamoaFlood management Action Plan 2007 48

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATEProcure computers,software - GIS, rainfallprediction modelEquipment purchasedand utilisiedImproved capacity andnumber of up to datehardware and software2008 – upgradesongoingRESPONSIBLEAGENCIES• TARGET AGENCIESMNRE-WRDMNRE-MeteorologyMNRE-PUMAMNRE-TSDGOAL 4 : TECHNOLOGICAL INFORMATION MANAGEMENTOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE10. ImproveMore reliable data Reduced uncertainty in Ongoingdata collection andavailable for modelling: the flood modelinformationmanagement systemsto guide and supportflood management atthe catchment’s levelCollect and manage floodrisk information that is usedto direct flood mitigationactions such as:• flow• rainfall intensity• watershed hydrologyand river channelhydraulics• Topographicsurveys includingincreased crosssections acrossflood plains andcritical sectionsRESPONSIBLE AGENCY• TARGET AGENCIESMNRE-WRDMNRE-MeteorologyMNRE-TSD• SWAImprove and updateprecipitation, hydrologicaland hydraulic model of thecatchmentUpdate flood risk mapsthrough periodic revision ofthe need for flood studiesupdates• New flow dataincorporated intohydrological modelUpdated flood flowsand levelsUpdated mapsavailableNumber of key sectorsand agencieseffectively applyingsame results to derivemanagement optionsUpdated mapsavailableOngoing2007 – upgradeongoingMNRE-WRDMNRE-MeteorologyMNRE-TSD• MNRE-PUMA• MWTI-Building Divisions• MWTI-RoadsMNRE-WRDMNRE-MeteorologyMNRE-TSDFlood management Action Plan 2007 49

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTING RESPONSIBLE AGENCYDATE• TARGET AGENCIESAssess water levels for anumber of different returnperiodsSpecified flood depthsfor each of the returnperiods available toReduced flood risk fornew development2007 MNRE-WRDMMNRE-MeteorologyMNRE-PUMAcontrol development• DevelopersInstall new flow gaugingstations upstream of AlaoaEast and at other branchesof Vaisigano and at otherselected sitesEstablish a datamanagement procedure tocollect, analyse, archiveand back-up dataDigitise historical rainfalldataProduce a flood hazardmap for each of themodelled return periodsImproved flow datarecordsDatabase in place anddata are backed updata including real-timedataHistorical rainfallrecords availabledigitally and archivedFlood hazard zonesdelineated based onwater level and velocityfor each return periodFlow gauging stationsinstalledFlow database archivedHistorical flow recordsaccessibleAll records availabledigitally and backed-upPreliminary floodhazard map producedOngoingMNRE-WRDMNRE-Meteorology2008 MNRE-MeteorologyMNRE-WRDMNRE-ICTOngoing2006 – ongoingfor other riversMNRE-MeteorologyMNRE-WRDMNRE-MeteorologyMNRE-TSDMNRE-PUMAIdentify and collect relevantinformation (people,property and infrastructure)required to produce a floodrisk mapProduce a flood risk mapfor major river catchmentsElements at riskidentified – people,property andinfrastructureMap of elements at riskproducedRequired demographic,infrastructural andproperty data availableFlood risk map showingnumber of people andnumber of buildingsaffected and potentialeconomic damage andpotential loss of life2007 – updateongoing2007 (Vaisigano)- others ongoingMNRE-TSDMNRE-PUMAMNRE-WRDMNRE-Meteorology• MWTIMNRE-TSDMNRE-DMOMNRE-WRD• Community• InsuranceFlood management Action Plan 2007 50

GOAL 5 : SUSTAINABLE WATERSHED MANAGEMENTOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATE11. Strengthened the Review the draftDevelopment control SMP endorsed andSMP for floodplain and Sustainable Management and conditions closely implementedwatershedPlan (SMP) and develop a linked to catchmentdevelopment guideline for floodplain status and environment(management) developmentEstablish an inter-agencyplanning andimplementation procedureto reduce flood risk.Implementationprocedures approvedImproved coordinationat the planning and theimplementation stagesRESPONSIBLE AGENCY• TARGET AGENCIES2007 MNRE-PUMA• DevelopersOngoingMNRE-WRDMNRE-LMDMNRE-FDMNRE-PUMAReview and prioritiseappropriate land usezoning for different levelsof flood risk in the majorwater catchmentsReview and developregulations to control newor expanded developmentin flood risk areasRecommendedsustainable landusetypes for different levelsof flood risk to reducepotential impactsImplementation andenforcement ofregulationsCopies of approved andupdated Plan availableUpdated landuse GISmaps availableIncreased number ofnew developmentincorporating floodmitigation measures2008 MNRE-WRDMNRE-LMDMNRE-FDMNRE-PUMA• MAF• Land owners• Communities2009 MNRE-WRDMNRE-PUMAMNRE-TSD• MWTI-Building Divisions• MWTI-RoadsFlood management Action Plan 2007 51

GOAL 6 : FLOOD GOVERNANCEOBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTING RESPONSIBLE AGENCYDATE12. Strengthen policy,legislative andorganisationalarrangements for acoordinated andIdentify social andeconomic benefits ofimplementing integratedflood management options(structural and nonstructural)Cost-benefit andappraisal proceduresand recommendationscompletedIdentified sustainableoptions implementedand promoted2008 MNRE-WRDMNRE-PUMAMNRE-LMDMWTISWAeffective flood risk• MOFmanagement• MNRE-DMOReview relevant policy andlegislation to provide forflood risk managementresponsibilities to beexplicitly definedIncorporate floodmanagement in nationalmacroeconomic policy andfiscal managementIncorporated key actions ofthis Action Plan in relevantagencies annualworkplans/business plansTransparent andaccountableorganisationalmanagementarrangementsmandated to control,monitor and provideinformation on floodsmitigation,preparedness,response and recoveryFlood managementreflected as a prioritydevelopment agendaand allocated withappropriate level ofresourcesFlood management is aspecific budget lineitem in eachMinisterial/Divisionbudget allocationClear organisationalroles and responsibilityto be reflected inrelevant policyPercentage of nationalannual budgetallocated to floodmanagementReflected in SDSPercentage ofministerial/divisionbudget allocated toflood management• MWCSD2009 AGMNRE-WRDMNRE-MeteorologyMNRE-PUMAMNRE-Legal servicesMNRE-DMO2007-2009 MOF/ACUMNRE-WRDMNRE-DMO2007-2009 MNRE-DMOMNRE-TSDMNRE-MeteorologyMNRE-WRDMWTI-Building DivisionFlood management Action Plan 2007 52

OBJECTIVE KEY ACTIONS EXPECTED RESULTS INDICATORS STARTINGDATEDevelop a detailedimplementation programmefor this Action Plan linked toannual workplans, relevantnational projects andidentify potential donorsAction Planimplementation startsNumber of successfulactions implemented ina yearRESPONSIBLE AGENCYMWTI- Road DivisionMOHSWA2007-2009 MNRE-WRDMNRE-DMOMNRE-TSDMNRE-MeteorologyMWTI-Building DivisionMWTI-Road DivisionAnnual reviewsector/ministerial regulatoryand planning processes forflood managementEstablish a technicaladvisory committee toreview and monitor theimplementation progress ofthis Action PlanPlanning process forflood managementbeing reflected in eachagency’s work plan andrespective goalsReview process for theprogress of the ActionPlan in placeImproved Flood riskmanagementTechnical advisorycommittee establishedto oversee the reviewprocessOngoigMidimplementationand at the end inview of reviewand updating ofthe PlanMNRE-WRDMNRE MeteorologyMNRE-PUMAMNRE-DMOMNRE-TSDMWTI-Building DivisionsMWTI-Road DivisionsSWAand all other relevantstakeholdersMNRE-WRDMNRE-DMOAnd a33gencies responsible forflood management incollaboration with provincial andsector agencies and communityleaders.Flood management Action Plan 2007 53

5. ReferencesCIRIA (2004) Development and flood risk – Guidance for the construction industryEUROPEAN COMMISSION (2005) Ecoflood Guidelines - How to use floodplains forflood risk reductionFAO TCP/SAM/8851 (1990), Vaisigano River Watershed Management Plan, Foodand Agriculture Organisations, UN.Government of Samoa (2001) Report of the Census of Population and Housing 2001.168 ppGovernment of Samoa (2006), Samaoa’s National Disaster Management Plan 2006-2009, Ministry of Natural Resources, Environment and Meteorology, Apia Samoa.Government of Samoa (2006), Samoa’s National Action Plan (NAP), for combatingdesertification, Ministry of Natural Resources, Environment and Meteorology, ApiaSamoa.HR WALLINGFORD LTD (2005) Guidance on national flood risk assessments HRWallingford report EX5096HR WALLINGFORD LTD (2005) Source book for sustainable flood mitigationstrategies HR Wallingford report EX5095HR WALLINGFORD LTD (2005). FD2321/TR1. Flood Risks to People Phase 2.Technical Report 1: The Risks to People MethodologyKELLOGG, BROWN AND ROOT PTY (2006) Institutional strengthening for drainageand wastewater management in Apia, Samoa – Interim report – October 2006PUMA (2006) Draft Sustainable Management Plan (No. 1) - Guidelines for theDevelopment of Land Adjoining Rivers, Streams and on Flood Prone Land andPriority Actions for Mitigating Drainage Impacts in the Catchments of Urban ApiaPUMA report September 2006SCARM (2000) Floodplain management in Australia – Best practice principles andguidelines SCARM Report 73, Agriculture and Resource Management Council ofAustralia and New Zealand, CSIRO PublishingSOPAC (2006) Capacity Building in Flood Risk Management – Technical report EUEDF 8 – SOPAC Project Report No : ER0069aUK GOVERNMENT DEPARTMENT OF ENVIRONMENT FOOD AND RURALAFFAIRS (2004) Making Space for Water. Consultation document on thedevelopment of a new Government strategy for flood risk and coastal erosionmanagementUNDP/GEF (2006), Land Degradation Thematic Assessment Report, Ministry ofNatural Resources, Environment and Meteorology, Apia Samoa.WORLD BANK (2002) Coastal Infrastructure Management Plan Vaimauga EastDistrict, Samoa - Plan Development February 2002Flood management Action Plan 2007 54

6. AnnexesAnnex 1: The Process carried out in Samoa to develop thePlanThe process contains the following related activities:o Capacity building in flood hydrologyo Capacity building in river modellingo Capacity building in floodplain mappingo The production draft floodplain management guidelines for Samoa to reduceflood risko The production of a Flood Risk Management Action Plan for the lower VaisiganoRiverThe first three initiatives were addressed as phase 1 in July and August 2006 throughfieldwork and training in the Vaisigano catchment involving officers from Meteorology,PUMA and Water Resources.The objective of phase 2 was to develop draft floodplain management guidelines anda flood management action plan based on the information available and otherexisting initiatives in Samoa and to provide additional training in flood riskmanagement.The draft guidelines and action plan were developed as follows:31 October to 17November (2006)Further training with a core group that participated in phaseoneFace-to-face consultation, desk reviews, and linking withother relevant projects through consultation20 to 21 November Workshop – present preliminary findings of the technicaltraining on mitigation options to reduce flood in VaisiganoIntroduce guideline and action planWorking groups to identify issues to be addressed by theguideline and action plan22 to 28 November Guideline and action plan development with the core group28 to 29 November Presentation of the first draft of the guideline and ActionPlan to key Government Agencies30 November Broad circulation of the draft for commentsComments are to be received either through the MNRE-WRD or directly to SOPAC for the final incorporation, finalediting and printing1 st quarter of 2007 Final guideline and action plan produced and endorsementprocess to be undertaken by the Samoa GovernmentFlood management Action Plan 2007 55

Annex 2: Glossary of DefinitionsACCEPTABLE RISKThe level of loss a society or community considers acceptable given existing social,economic, political, cultural, technical and environmental conditions. In engineering terms,acceptable risk is also used to describe structural and non-structural measures undertaken toreduce possible damage at a level, which does not harm people and property, according tocodes or “accepted practice” based, among other issues, on a known probability of hazard.AFFECTED POPULATIONPrimary: People requiring immediate assistance during an emergency situation.Secondary: People who at a certain point will require long-term social and economicassistance as a direct consequence of a disaster situation.BUILDING CODESOrdinances and regulations controlling the design, construction, materials, alteration andoccupancy of any structure for human safety and welfare. Building codes include bothtechnical and functional standards.DAMAGEUnwanted changes or losses resulting from a natural or human-caused event.DAMAGE ASSESSMENT Identification and qualitative and quantitative recording of theextent, severity and location of the effects of a destructive event.DECLARATION OF DISASTEROfficial declaration by the authorities of a political-management jurisdiction to meet the needfor extraordinary action.DIRECT EFFECTS Those effects having a direct cause and effect relationship with the event.DIRECT LOSSES Adverse effects caused by a disaster, such as the loss of life, injuries, lossof goods and services, and infrastructure damage.DISASTERA serious disruption of the functioning of a community or a society causing widespreadhuman, material, economic or environmental losses which exceed the ability of the affectedcommunity or society to cope using its own resources. A disaster is a function of the riskprocess. It results from the combination of hazards, conditions of vulnerability and insufficientcapacity or measures to reduce the potential negative consequences of risk.DISASTER MANAGEMENTThe organisation and management of resources and responsibilities for dealing with allaspects of emergencies/disasters, in particular preparedness, response and(relief/rehabilitation)DISASTER RISK MANAGEMENTThe systematic management of administrative decisions, organisation, operational skills andabilities to implement policies, strategies and coping capacities of the society andcommunities to lessen the impacts of natural hazards and related environmental andtechnological disasters. This comprises all forms of activities, including structural and nonstructuralmeasures to avoid (prevention) or to limit (mitigation and preparedness) adverseeffects of hazards.DISASTER RISK REDUCTIONThe conceptual framework of elements considered with the possibilities to minimisevulnerabilities and disaster risks throughout a society, to avoid (prevention) or to limit(mitigation and preparedness) the adverse impacts of hazards, within the broad context ofFlood management Action Plan 2007 56

sustainable development.DISASTER WARNING SYSTEMArrangements and procedures to alert to and warn the community of the possibility of adisaster event and suggest actions that should be taken to reduce its impact.EARLY WARNINGThe provision of timely and effective information, through identified institutions, that allowindividuals exposed to a hazard, to take action to avoid or reduce their risk and prepare foreffective response. Early warning systems include of three primary elements (i) forecasting ofimpending events, (ii) processing and dissemination of warnings to political authorities andpopulation, and (iii) undertaking appropriate and timely actions.EMERGENCYA situation generated by the real or imminent occurrence of an event that requires immediateattention. A significant or unusual event, requiring the coordinated response of more than oneagency.ENVIRONMENTAL IMPACT ASSESSMENT (EIA)Study undertaken in order to assess the effect on a specified environment of the introductionof any new factor, which may upset the ecological balance. EIA is a policy making tool thatserves to provide evidence and analysis of environmental impacts of activities fromconception to decision-making. It is utilised extensively in national programming and forinternational development assistance projects. An EIA must include a detailed riskassessment and provide alternatives solutions.FLASH FLOOD A sudden and extreme volume of water that flows rapidly and causesinundation and because of its nature is difficult to forecast.FLOOD Significant rise of water level in a stream, lake reservoir or a coastal region. A floodis a harmful inundation of property and land utilised by man and may be of two types: slowflood, caused by an increase in the volume of water produced by rain in rivers and lakes overa long period, days or weeks, mainly affecting property such as houses and cattle, anddisplace the inhabitants from their usual dwelling places. Sudden flood, caused by anincrease in the volume of water in rivers and lakes, causing deaths, injuries and violentdestruction of property. It may be the result of torrential rain, hurricanes, and structuralfailures such as the collapse of walls of a reservoir or the embankment of a river provinginsufficiently robust to contain the strong flow or water.FORECASTDefinite statement or statistical estimate of the occurrence of a future event (UNESCO,WMO). This term is used with different meaning in different disciplines.LEVEL OF RISKAn expression of the severity of a risk derived from consideration of likelihood the event willoccur and the potential consequences that may arise.LIKELIHOODHow likely is it that a specific hazard will occur within a given time frame.MITIGATIONThe process of implementing measures that reduce the intensity and severity of the impact ofpotential hazards.MONITORTo check, supervise, observe critically, or record the progress of an activity, action or systemon a regular basis in order to identify changeNATURAL HAZARDSNatural processes or phenomena occurring in the biosphere that may constitute a damagingFlood management Action Plan 2007 57

event. Natural hazards can be classified by origin namely: geological, hydro meteorological orbiological.PREPAREDNESSThe process of implementing measures that are designed to ensure that, should a hazardthreaten, communities, resources and services will have the knowledge and understanding tocope with the effects.PREVENTIONActivities to provide outright avoidance of the adverse impact of hazards and means tominimise related environmental, technological and biological disasters. Depending on socialand technical feasibility and cost/benefit considerations, investing in preventive measures isjustified in areas frequently affected by disasters. In the context of public awareness andeducation, related to disaster risk reduction changing attitudes and behaviour contribute topromoting a “culture of prevention”.RECOVERYProgramming measures that are designed to support affected communities in thereconstruction of the physical infrastructure and restoration of emotional, economic andphysical well being.REHABILITATIONRestoring peoples lives back to normal, as well as essential services, including the beginningof the repair of physical, social and economic damages.RESPONSEProgramming measures that develop the action to be taken in anticipation of, during and /orimmediately after, a hazard impact to ensure its effects are minimised.RISKUsed to describe the likelihood of harmful consequences, arising from the interaction ofhazards, vulnerable elements and the environment.RISK ASSESSMENT/ANALYSISA process to determine the nature and extent of risk by analysing potential hazards andevaluating existing conditions of vulnerability that could pose a potential threat or harm topeople, property, livelihoods and the environment on which they depend. The process ofconducting a risk assessment is based in a review of both the technical features of hazardssuch as their location, intensity, frequency and probability; and also the analysis of thephysical, social, economic and environmental dimensions of vulnerability, while takingparticular account of the coping capabilities pertinent to the risk scenarios.RISK IDENTIFICATIONThe process of determining what can happen, why and howTREATMENT OPTIONSMeasures contained within mitigation, preparedness, response and recovery programmesthat aim to eliminate or drastically reduce the level of riskVULNERABILITYMeans that element are exposed to specific hazard an have a low level of resilience to copewith the impacts of that hazard (i.e. cyclone) or characteristics of the (i.e. storm surge offlooding)Flood management Action Plan 2007 58

Annex 3: Stakeholder Consultation Workshop for the FMAP –List of ParticipantsWATER RESOURCES DIVISION /MNREMr Suluimalo Amataga PenaiaACEOPh: [685] 23701/23702Fax: [685] 25421E-mail: amataga.penaia@mnre.gov.wsMETEOROLOGY DIVISION / MNREMs Siosina LuiCountry Intern, SamoaMulinuuPh: [685] 20855Fax: [685]E-mail: slui@meteorology.gov.wsMs Masina Ngau ChunSenior Scientific OfficerWater Resources DivisionMatautu TaiPh: [685] 23701/23702Fax: [685] 25421E-mail:Masina.NgauChun@mnre.gov.wsMr Lameko AsoraPrincipal Hydrology OfficerWater Resources DivisionPh: [685] 23701/23702Fax: [685] 25421E-mail: lameko.asora@mnre.gov.wsFAOMr Paul TomaneAssistant Representative (Prog.)FAO Sub Regional OfficeMatautu UtaPh: [685] 22127Fax: [685] 22126E-mail: Paul.Tomane@fao.orgNATIONAL PACIFIC INSURANCEMs Maselina TevagaBranch ManagerNational Pacific Insurance1 st Floor, NPF BuildingApiaPh: [685] 23 634Fax: [685] 23 374E-mail: leena.npi@samoa.wsFlood management Action Plan 2007 59

EPCMr Sale FaletoluEnvironmental CoordinatorJohn Williams BuildingApiaPh: [685] 65413/777 6625Fax: [685] 23748E-mail: faletolus@epc.wsWaSSPMr Russell AbramsApiaPh: [685] 34484/22975Fax: [685] 21312E-mail: rabrams@paradise.net.nzSUNGOMr Raymond VoigtNational PresidentPO Box 1858ApiaPh: [685] 24322Fax: [685] 20 654E-mail: sungo@lesamoa.netSamoa Fire Emergencies ServicesAuthorityMr Fouina MupoInspectorPh: [685] 20405Fax: [685] 20457E-mail:samoafireservices@lesamoa.netSAMOA WATER AUTHORITYMr Ekiumeni FauoloProject EnigineerPh: [685] 20409Fax: [685] 21298E-mail: efauolo@swa.gov.wsADB PROJECTMr David PowerSSDP Team LeaderPh: [685] 778 6037Fax: [685] 22 566E-mail: ghd_tl@samoa.wsPUMAMr Iosefa AiolupoteaTechnical Planning OfficerPUMAPO Box 6171Ph: [685] 779 2209/23986/25784Fax: [685] 25794E-mail:iosefa.aiolupotea@mnre.gov.wsIosefa_a@yahoo.comMr Tumau PeniSustainable Development PlannerMNRE-PUMAPh: [685] 23986/25784Fax: [685] 25794E-mail: tumau.peni@mnre.gov.wsMAPPING DIVISION / MNREMr Leoo PoluteaPrincipal Mapping OfficerMatautu TaiPh: [685] 32741/ 22481Fax: [685] 23176E-mail: Leoo.Polutea@mnre.gov.wsTrainerMr Darren LumbrosoProject ManagerWater Management DepartmentHR Wallingford LtdHowbery Park, WallingfordOxon, OX10 8BAUKPh: [44] 0 1491 835381Fax: [44] 0 1491 826352E-mail:d.lumbroso@hrwallingford.co.ukFlood management Action Plan 2007 60

SOPACDr. Netatua PelesikotiSustainable Deveopment AdvisorPrivate Mail BagSuvaFiji IslandsPh: [679] 338 1377Fax: [679] 337 0040E-mail: netatua@sopac.orgOne-to-one consultation wasconducted with the following:Mr Mulipola Ausetalia TitimaeaAssistant Chief Executive OfficerMeteorology DivisionMinistry of Natural Resources Environment and MeteorologyTel: (685)20855/20856Fax: (685)20857Sagato TuiafisoMeteorology DivisionMr Amataga PenaiaAssistant Chief Executive OfficerHydrology DivisionLudo Prins, Ministry of Foreign Affairsludo.prins@mof.gov.wsNadia Meredith, Ministry of Foreign Affairsnadia.meredith@mof.gov.wsNigel Warmsleynigel@ipasifika.netLatu KupaLatu@kew.com.wsWaSSPMr Russell AbramsApiaPh: [685] 34484/22975Fax: [685] 21312E-mail: rabrams@paradise.net.nzADB PROJECTMr David PowerSSDP Team LeaderPh: [685] 778 6037Fax: [685] 22 566E-mail: ghd_tl@samoa.wsMs Litea BiukotoHazard Assessment AdvisorSOPACPrivate Mail BagSuvaFiji IslandsPh: [679] 338 1377Fax: [679] 337 0040E-mail: litea@sopac.orgMs Alena Lawedrau-MorocaWater Resources OfficerSOPACPrivate Mail BagSuvaFiji IslandsPh: [679] 338 1377Fax: [679] 337 0040E-mail: alena@sopac.orgFlood management Action Plan 2007 61

Annex 4: Consolidation of existing statutory and non-statutory flood risk reduction activities in SamoaAgency Flood risk reduction related activities Recommendations Relevant legislative mandates forMinistry of Natural Resources,EnvironmentMinistry of Works, Transportand Infrastructure (MWTI) –Infrastructure Assets –BuildingMWTI - Infrastructure Assets –Roads Samoa Development Planning provisionso Sustainable management plans (SMP)– including a draft guide for housingo Development consents (localities anddesigns of new developments areassessed where Development Consentmay be subject to Conditions.o Environment Impact Assessmento PUMA advice (e.g. to developers onhazard (flood) risk areas and possibleadverse and long term ecological andsocial implications)o Monitoring Building regulations Risk assessments construction andmaintenance of public assets Orders in relation to unsafe buildings Code of Environment Practice RoadPlanning, Design, Construction andmaintenance Design specification Roadwork’s specifications EIAs Emergency maintenance and Emergencyresponse Recovery constructionProposal for the development on floodplains orhigh flood prone areas – conditions could includeheight of floor, drainage location and design,distance from surface water source etc.Depending on the locality of the proposal – andensuring that it is clear in the TOR for thescoping phase or for a full EIA to considerimpacts of the proposed development on thefloodplain and river/streams as well as theimpact of the risk of flooding on the development– and to identify appropriate mitigation optionsMonitoring of conditions given with thedevelopment license clearly a function of PUMA.However who should monitor the mitigationmeasures not attach to development licensesuch as mitigation structures – usuallygovernment development projectsConditions for building on floodplains and floodrisk areas such as Apia should be incorporatedinto the assessment of building designsNeed to consider building that are alwaysflooded and look into options such as relocation,raising of floor level, building a flood wall orimproving drainageConditions for infrastructure building onfloodplains and flood risk areasmitigationPlanning and Urban Management Act2004EIA guidelines 1998Code of Environment Practice 2001Coastal Infrastructure ManagementDraft Housing guidelines 2003Draft building regulations 2003National Building Code 1992Ministry of Works Act 2002Code of Environment Practice 2001EIA guidelines 1998Planning and Urban Management Act2004Ministry of Works Act 2002Flood management Action Plan 2007 62

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