New Book: Watersheds of the World

12/05/1998

Ramsar sites shown on 145 maps of the world's catchment basins


The World Resources Institute and the Worldwatch Institute have jointly published an excellent new ca.200-page softcover book entitled Watersheds of the World: ecological value and vulnerability, by Carmen Revenga, Siobhan Murray, Janet Abramovitz, and Allen Hammond.  Summary analyses of the data preface the volume, followed by individual maps, tables, and graphs on nearly 150 watersheds around the world, with Ramsar Wetlands of International Importance shown on the maps.   Single copies are available for US$ 30.00 plus US$ 5.00 handling from WRI Publications, P.O. Box 4852, Hampden Station, Baltimore, Maryland 21211, USA.

Further information can be sought from Carmen Revenga, Research Analyst at WRI, carmenr@wri.org .

Here is an abstract of the book's contents that has been provided by the publishers.


Abstract -- Watersheds of The World: Ecological Value And Vulnerability

Carmen Revenga, Siobhan Murray, Janet Abramovitz and Allen Hammond

A Joint Publication by the World Resources Institute and Worldwatch Institute

watershedbook.jpg (44780 bytes)This report presents and analyzes for the first time global data at the watershed level, assessing 145 major watersheds around the world. The study focuses on watersheds as ecosystem management units and on the risks of degradation from human activities, shedding light on the importance of; threat to, and vulnerability of freshwater biodiversity.

Given the ecological importance of watersheds and the extent of human dependence on the services provided by them, watershed degradation has potentially enormous environmental and socio-economic costs. Yet efforts to develop and use the goods and services provided by watersheds have not been well integrated with efforts to protect and manage watersheds sustainably. For example, removal of forests or other vegetation upstream can sharply reduce water retention and increase erosion, reducing water availability in dry seasons and increasing siltation downstream. The construction of dams affect migratory fish populations, and can often degrade fisheries, disrupt aquatic ecosystems, and prevent the renewal of soil by flooding and siltation, reducing food supplies. Pollution from human activities can degrade water quality and even make water unusable for human needs, as well as threatening other species. Excessive withdrawal of water can damage or even destroy aquatic ecosystems and surrounding regions, as happened with the Aral Sea. Changes in river flow and sediment and pollutant loadings resulting from activities far inland can degrade downstream coastal ecosystems, such as mangroves and coral reefs. Sometimes downstream activities can even affect upstream conditions, as when alien species introduced into watersheds migrate upstream and threaten fisheries or economic activities. These linkages illustrate how watershed development can have unplanned and inadvertent effects--sometimes with devastating consequences--and underscore the importance of managing watersheds as integral units and of planning development with the entire watershed in mind.

This study uses 15 global indicators to characterize watersheds in terms of their value, current condition, and vulnerability to potential degradation. Indicators used to represent watershed value include: fish species richness and endemism, bird species endemism, aridity, population density, and water scarcity. Watershed condition indicators include, modified landscape, irrigated cropland, existing major dams, remaining original forest, extent of original forest loss, and soil erosion from water. Finally, indicators for future vulnerability include: growth rate of urban centers, tropical deforestation for the period 1980-1990, planned major dams, and current level of protection. These indicators, presented as maps, give a unique global perspective on the world' s largest transboundary watersheds as well as many smaller basins. These indicators provide an initial tool to approach watershed management, and highlight the data gaps needed to manage resources at the watershed level.

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