Northland Civil Defence Emergency Management Plan, 2010

GEOLOGYNorthland's geology is a mixture of basement rock (greywacke), volcanic rock, sedimentary rocks, alluvial material,and sands. Uplifted blocks of hard blue-grey sandstone (greywacke) extend along the east coast from north of theBay of Islands as far south as the Brynderwyn range, and inland from Whangarei. To the west of these surfaceoutcrops, greywacke forms a basement deep beneath various sedimentary and volcanic rocks. Old volcanic rockoutcrops are a dramatic feature of the Northland landscape. Land slips are a frequent consequence of rain inNorthland due to the steep topography and the soil structure.Rising sea levels have drowned river valleys to create several harbours which extend well into the interior of theregion. As a result, rivers tend to be short, dropping quickly in bouldery streams from higher country, and thenmeandering sluggishly through mangrove lined channels into harbours and estuaries.CLIMATENorthland has a sub-tropical climate that is characterised by mild, humid and often windy weather. The regionexperiences, on average, 2,000 hours of sunshine per year. Winds are mostly south-westerly but tropical cyclonesin the summer bring strong north-easterly winds and heavy rainfall. Northland’s rainfall distribution pattern isdictated by its narrow shape and its topography. Annual rainfalls range from 900 millimetres in low-lying coastalareas to over 2,900 millimetres in higher altitude areas such as Tutamoe Plateau. Seasonal influences on rainfallare well defined due to the seasonal movement of high pressure belts with up to one third of the annual totaloften falling in the three winter months. Northland also experiences high intensity rainfalls which can result inflash floods.HUMAN MODIFICATIONHuman modification of the natural environment can both worsen and mitigate natural processes that createhazards. Land change has generally led to an increase in hazards, particularly floods, landslides, and coastalhazards. Restoration of catchments, wetlands, dunes and other natural systems is now recognised as an integralpart of hazard management. In Northland this is promoted through the distribution of funds to Northlanders torevegetate land, protect wetlands and riparian margins, and promote restoration and management of duneenvironments. It is also controlled through land use planning.2.1.5 IMPLICATIONS FOR THE CDEM GROUP ENVIRONMENTThe implications of Northland’s regional profile for civil defence emergency management are identified below.These issues have been considered in developing the CDEM work plan and priorities.1. Numerous rural communities have the potential to become quickly isolated in an emergency because of theirremoteness, access (often gravel roads) and geography. Self-reliance and preparedness become even moreimportant for these communities.2. The vulnerability of some of the region’s infrastructure (power, roads) may impact on the ability of the regionto recover quickly from an emergency. Increased awareness of the region’s vulnerability to infrastructurefailure may help to encourage businesses to have their own backup systems and become more resilient tothese failures.3. The dependence on farming and horticultural industries means that the economy is vulnerable to hazards thatimpact those sectors (animal/plant diseases, drought, storms).4. The high percentage of Maori in the community may mean a need to communicate information about hazardsand preparedness measures differently.5. Communication strategies will need to consider internet access, which is below the national average. Forexample, not relying wholly on the NRC website to provide hazard information to communities.6. There are some communities/households without telecommunications, making them particularly vulnerablein an emergency.7. The high number of holiday homes can have an influence as holiday homes are less likely to have stocks toenable self-sufficiency for several days. Also, there is a belief that in a major Auckland disaster manythousands of people may self-evacuate to holiday homes in Northland.8. Northland has high levels of socio-economic deprivation, which means that many communities are moresusceptible to adverse effects of hazards and have less resources to support recovery.Northland Civil Defence Emergency Management Plan, 2010-2015 Page 20