Water for people.pdf - WHO Thailand Digital Repository

P R O T E C T I N G E C O S Y S T E M S F O R P E O P L E A N D P L A N E T / 1 3 9Map 6.1: Relative naturalness of land in major world river basinslow medium high no dataThis map shows the area of spaces formed by the forces of nature, and where humankind’s imprint is not yet significant. Vast regional and continental disparities can benoted, corresponding to a large degree to population density disparities.Source: Map prepared for the World Water Assessment Programme (WWAP) by the Centre for Environmental Research, University of Kassel, Germany, based on data from UNEP-WCMC from 1998.correlated with impacts on land, the results (see map 6.1) provide aguide to the possible condition of aquatic systems within each basin.This measure is indirect and therefore somewhat imprecise because,for example, pollutants from a point source may significantly impairwater quality while the terrestrial catchment remains relativelyundisturbed (as is the case for parts of the Amazon drainage basinin South America). Nonetheless, the impact of social and economicdevelopment on the natural state of the environment is clear, andlack of data for key areas is highlighted.A more direct indication of current condition can be derivedfrom the vast amount of global water quality data available. Aglobal assessment (UNEP, 2002), developed with the participation ofnational and regional experts noted inter alia the widespreadoccurrence of poor water quality, the diversion of water fromnatural aquatic ecosystems, and the emerging problems withgroundwater quality and recharge.Pressures are particularly severe in developing countries whereinstitutional and structural arrangements for the treatment ofmunicipal, industrial and agricultural are often poor. This is reflected inincreased pollution from industrial organic substances, acidifyingsubstances from mining and atmospheric emissions, heavy metals fromindustry, ammonia, nitrate and phosphate pollution from agriculture,pesticide residues (again from agriculture), sediments from humaninducederosion to rivers, lakes and reservoirs and salinization.In developed countries, waste-treatment facilities have reducedlevels of bacteriological contamination and key issues with regard towater pollution are persistent substances, including pesticides,hydrocarbons and endocrine disruptors. In both developed anddeveloping countries, loss of ecosystem integrity through poorwater quality compromises the use of the resource for drinkingwater, food production and other aspects of human health. One ofthe most significant forms of river pollution is nutrients, although inrecent years introduction of tertiary treatment of wastewater hasresulted in improved levels of phosphorus and organic matter (butnot in nitrate levels) in many more developed countries.