Water for people.pdf - WHO Thailand Digital Repository

B A S I C N E E D S A N D T H E R I G H T T O H E A LT H / 1 1 7clearly lacking throughout the world at the present time. A favourablepolicy climate is essential for this body of trained personnel to functionproperly, with special attention to policies in all water-associatedsectors, conducive to intersectoral cooperation. Health sector personnelwill benefit from training in impact assessment procedures andmethods, and will be better placed to appreciate the concerns of theother sectors responsible for water projects. The health sector structurealso needs renewal to allow for a better response to the needs incurredby HIA, i.e. contributing to terms of reference, HIA appraisal, monitoringhealth determinants and of compliance with recommended measures. Inturn, water resources and water user sectors should work towardsdeveloping an understanding of the association between their decisionsand human health. Where lacking, all groups should develop skills inintersectoral communication, collaboration and community participation.A course manual on developing such skills in support of HIA will bepublished in 2003 (Bos et al., 2003).Water management practice options to protect or promotehealth range from canal lining in irrigation schemes to speciallydesigned reservoir management programmes in dam projects. Damsoften illustrate these issues in a clear, admittedly sometimesextreme way. The following best practice list was compiled as part ofWHO’s input into the work of the World Commission on Dams.There are a number of fully or partially validated options thatcan mitigate the adverse effects of dam construction on humanhealth. Examples of such health safeguards relating to operationalwater management include (WHO, 2000):1. Design options■ Multiple depth off-takes that allow the release of first flushinflows that may contain high levels of contaminants andnutrients, and allow a high level of control of fluctuation inreservoir water level (which can be advantageous in thecontrol of disease vectors such as snails and mosquitoes).■ Double spillways in areas where onchocerciasis (riverblindness) is endemic. Spillways have been shown to providean appropriate habitat for the breeding of blackflies(Simulium ssp.), the vectors of the Onchocerca parasite; theiralternate use will prevent such breeding.■ At all potential sites, ensuring careful examination of reservoirbathymetry so as to avoid dam sites that have extensiveshallow areas conducive to insect and snail breeding. Whileshallow margins can never be totally avoided, catchmenttopographies that give rise to large reservoirs of low averagedepth (and therefore large wetted perimeters) should beavoided. Such reservoirs will also be undesirable from anevaporative-loss point of view.■ Provision of simple infrastructure (jetties, for example) atcritical places along the reservoir shore to reduce water contactfor specific target groups (fishermen, women, children).■ A greater than standard diameter of off-takes will allow the rapiddraw-down of reservoirs, allowing a rapid drop in shoreline waterlevels, stranding and killing mosquito vectors (provided no poolformation occurs) and intermediate host snails of schistosomiasis.This will also allow an artificial flood downstream that will flushout any vector breeding places in rock pools.■ Careful settlement planning that ensures that, whereverpossible, and in balance with other planning and socialneeds, population settlement occurs away from areas ofimpounded and slow-flowing water. This will minimize humanexposure to disease-carrying vectors.■ Adequate planning for, and design of, community watersupply and sanitation, including careful management ofsewage and waste. This will reduce the rate of reservoireutrophication and the occurrence and severity of toxiccyanobacterial blooms, as well as reducing water pollutiongenerally.2. Reservoir options■ In-reservoir management to prevent eutrophication andexcessive growth of problematic organisms such as toxiccyanobacteria and aquatic weeds. The development of massiveblooms of toxic cyanobacteria is an area of increasing concern,especially in poorer countries where drinking water treatmentmay be less common or absent, and where exposure to toxicblooms may go unmanaged or unreported (see box 5.5).■ Well-formulated dam environmental management plans thatwill support sustainable fisheries practices, sustainpopulations of natural predators of disease vectors andminimize excessive growth of aquatic weeds.■ Catchment management to minimize negative impacts on theimpoundment, including those from population growth andagricultural development in the upper catchment.■ Adequate in-flow forecasting for disaster prevention in case ofincreased settlement on the downstream floodplain and heavylivelihood dependence on new agricultural production system.■ Water release regimes that minimize impacts on downstreamecology and productivity especially in regions where there is