Water for people.pdf - WHO Thailand Digital Repository

1 0 / S E T T I N G T H E S C E N EThe World’s Water CrisisWhile the environment does have the capacity to cope withcertain kinds of pollution, where exceeded, pollution can result inwatercourse contamination beyond use, which can in turn result incostly treatment procedures as well as the loss of people’slivelihoods (e.g. loss of fish stocks and other aquatic life).Another aspect of environmental sustainability is its ‘unfair’effect on the poor. It is the poor people who often have to live in‘undesirable’, marginal areas, more at risk from floods, etc.Furthermore, the poor often live in closer relationship with theenvironment, and do not have an alternative open to them as dothe wealthy, when, for example, a fish stock is depleted. Theworld’s poor suffer disproportionately as a result. These aspects andmore are further explored throughout this chapter.Water Resources in CrisisWater resources can only be understood within the context of thedynamics of the water cycle. These resources are renewable (exceptfor some groundwater), but only within clear limits, as in mostcases water flows through catchments that are more or less selfcontained.Water resources are also variable, over both space andtime, with huge differences in availability in different parts of theworld and wide variations in seasonal and annual precipitation inmany places. This variability of water availability is one of the mostessential characteristics of water resource management. Most effortsare intended to overcome the variability and to reduce theunpredictability of water resource flows.Both the availability and use of water are changing. Thereasons for concern over the world’s water resources can besummarized within three key areas: water scarcity, water quality andwater-related disasters. Each is discussed briefly here and expandedon throughout this report.Water scarcityThe precipitation that falls on land surfaces is the predominant sourceof water required for human consumption, agriculture and foodproduction, industrial waste disposal processes and for support ofnatural and semi-natural ecosystems. The fate of this water is either tobe ‘taken up’ by plants and the soil and then eventually returned tothe atmosphere by evapotranspiration, or to drain from the land intothe sea via rivers, lakes and wetlands. Our primary source of water isrunoff diverted by humans for use in irrigated agriculture, in industryand in homes (rural and urban); for consumption of various kinds; andfor waste disposal. It is the water of evapotranspiration that mainlysupports forests, rainfed cultivated and grazing land, and a variety ofecosystems. Despite a withdrawal of only 8 percent of total annualrenewable freshwater resources, it has been estimated that 26 percentof annual evapotranspiration and 54 percent of accessible runoff isnow appropriated by humans (Shiklomanov, 1997). As the per capitause increases due to changes in lifestyle (leisure and domesticpractices) and as population increases, the proportion of appropriatedwater is increasing. This, coupled with spatial and temporal variationsin water availability, means that the water to produce food for humanconsumption, industrial processes and all the other uses describedabove is becoming scarce.It has been estimated that today more than 2 billion people areaffected by water shortages in over forty countries: 1.1 billion do nothave sufficient drinking water and 2.4 billion have no provision forsanitation (WHO/UNICEF, 2000). The outcome can mean increases indisease, poorer food security, conflicts between different users andlimitations on many livelihood and productive activities. Currentpredictions are that by 2050 at least one in four people is likely tolive in countries affected by chronic or recurring shortages offreshwater (Gardner-Outlaw and Engelman, 1997). At present manydeveloping countries have difficulty in supplying the minimum annualper capita water requirement of 1,700 cubic metres (m 3 ) of drinkingwater necessary for active and healthy life for their people (see map1.1). The situation is particularly grave in many of the cities of thedeveloping world. This is worrying given predictions of a 60 percentworld urban population by 2020. At present, half the population ofdeveloping countries live in water poverty.Flows of water are also essential to the viability of allecosystems. Unsustainable levels of extraction of water for otheruses diminish the total available to maintain ecosystems integrity.As land is cleared and water demand grows for agriculture andother human uses at the expense of natural ecosystems, theappropriation of evapotranspiration moisture by humans looks set tocontinue. This will inevitably lead to the further disturbance anddegradation of ‘natural’ systems and will have profound impactsupon the future availability of water resources. Actions to ensurethat the needs of the environment are taken into account as acentral part of water management are critical if present trends areto be reversed.This situation is aggravated by the fact that many waterresources are shared by two or more countries. Currently there are263 river basins that are shared by two or more nations and thatare home for roughly 40 percent of the global population. In themajority of cases, the institutional arrangements needed to regulateequity of resource use are weak or missing.Water qualityEven where there is enough water to meet current needs, manyrivers, lakes and groundwater resources are becomingincreasingly polluted. The most frequent sources of pollution arehuman waste (with 2 million tons a day disposed of in