Water for people.pdf - WHO Thailand Digital Repository

4 2 4 / P I L O T C A S E S T U D I E S : A F O C U S O N R E A L - W O R L D E X A M P L E SRuhuna Basins, Sri LankaManagement Institute (IWMI) and others have shown that effectivewater management practices can contribute to eliminating the vectorthat causes malaria. Initiatives by the Ministry of Health, assisted by theWorld Health Organization (WHO) and the World Bank, in partnershipwith national agencies, have addressed the problem considerably.Sharing the resourceWater delivered through irrigation facilities is a common source ofdomestic supply for major towns and villages in the basin. Thus,during periods of water shortages, allocating water among differentuses becomes an issue.In one instance, the challenge of sharing water between sectors hasbeen further complicated by the prior water rights of Kaltota farmers,threatened by the Samanalawewa hydropower station. Constructedupstream of the irrigation scheme, the station extracts water from theriver to generate energy. As a result, farmers at the Kaltota scheme havehad to face occasional water shortages. After a period of intensenegotiations and bargaining, a consensus is being built among theauthorities dealing with irrigation and hydropower and the farmers.Evaluating the knowledge baseThere is a considerable range of data and knowledge about water andnatural resources in the Ruhuna basins and indeed in Sri Lanka ingeneral. However, the available data and information are scatteredamongst the different agencies. The World Water AssessmentProgramme (WWAP) has instigated recognition of the need for greateraccess to the available information and sharing of knowledge resourcesbetween the involved agencies. To this end, a comprehensive databaseis in the initial stages of design and implementation. The database willbe structured to enable monitoring of the WWAP challenge areas and,when complete, will allow improved sharing of data among the agencies.Identifying Critical Problems andOpportunitiesChallenges related to the nature of the resourceAnalysis of the meteorological and hydrological data confirms the hightemporal variability of rainfall and river flows. Of the three main rivers, alarge proportion of the available Kirindi Oya water resource is alreadydeveloped and there is little scope for further exploitation of the in-streamflows. In comparison, the water resources in the Menik Ganga basin arelargely undeveloped, but concerns about the impacts of abstraction onnature and wildlife are currently restricting development plans.Investigations show that groundwater quality is poor in the lowerreaches of the basins, i.e. in the dry zone. In several places, fluoride,hardness, chlorides, sulphate and alkalinity contents are reported tobe high, and shallow groundwater, in areas not recharged byirrigation, is falling in some locations due to increased use of agrowells,that is, wells supplying water to agriculture.Several water resource development projects are ongoing in theWalawe sub-basin, and other proposals are being studied. Withscientific investigations and planning, there is a potential for furtherdevelopment of groundwater. Potential investors in the proposedRuhunupura industrial complex have indicated their willingness to investin desalination of seawater to the Ministry of Southern Development.Challenges related to usesThe main water user in the basins is agriculture, principally for floodirrigatedpaddy, the predominant staple-food crop. Paddy cultivationon highly permeable soils has contributed to high water use and thuswater shortages and environmental problems. Studies carried out inselected irrigation schemes indicate that many farmers overapplypesticides, herbicides and nitrogen fertilizers (Renwick, 2001). Thecoastal lagoon system, which forms an important segment of thebasin’s ecosystem, receives a large volume of drainage flow duringthe irrigation seasons. This carries the residual wash-off of theseagrochemicals. Reduction of dry-weather base flows by irrigationabstractions and increased groundwater use are reported to haveaggravated the impacts of drought on the lagoon systems.In addition to environmental problems from agrochemical use,minor industries in the basin are an occasional source of pollution,such as the paper mill and sugar factories in the Walawe sub-basin.Several opportunities exist for improving the water useefficiency in agriculture. Increased reuse of irrigation return flows,diversification of crop patterns to include a higher proportion ofmore water-efficient crops, and the improvement of conveyancesystems, better canal operations and field application methodologiesare being introduced in the basins. Two donor-funded rehabilitationprojects are also supporting initiatives to increase productivity andwater use efficiency of the basins’ irrigation systems.It is argued that the village tanks, or dams, should not beconsidered merely as water sources and production systems butrather as a central part of the socio-economic and cultural systemof the rural area. The widespread distribution of minor irrigationsystems supports equitable access to water resources. However,transfer of technology innovations to minor irrigation and rainfedfarming is less intensive than in the major irrigation schemes.Opportunities do exist to promote higher productivity in rice andother traditional cereal crops in these areas and contribute tosustainable water resource development. Ongoing work for newirrigation facilities has taken these aspects into consideration.Further advances in the use of small-scale groundwater resources(for example through agro-wells) and modern irrigation techniques,including drip, trickle and sprinklers, are supporting increased areasof market-oriented crops.