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Publications / Water

WEAP: Water Evaluation And Planning System User Guide (for WEAP 21)

The Water Evaluation and Planning System (WEAP) aims to incorporate concerns about allocation of limited water resources, environmental quality, and sustainable water use into a practical tool for water resources planning. As a database, WEAP provides a system for maintaining water demand and supply information. As a forecasting tool, WEAP simulates water demand, supply, flows, and storage, as well as pollution generation, treatment, and discharge. As a policy analysis tool, WEAP evaluates a full range of water development and management options and takes account of multiple and competing uses of water systems.

The Effects of Irrigation on Wetland Ecosystems in Developing Countries: A Literature Review

This report reviews the scientific and “gray” literature to evaluate the extent to which irrigation has been shown to affect wetland ecosystems in developing countries. It aims to provide answers that may be useful in developing alternative future strategies for irrigation implementation and to assist in mitigating potential future ecological impacts. To the extent possible, it focuses on all potential types of impacts of irrigation on wetlands, including the effects of both water withdrawals upstream of the wetland and irrigation activities within the wetland itself.

Comprehensive Assessment of the Freshwater Resources of the World

This report examines water requirements to the year 2025 at regional and national levels to assess emerging problems of stress on freshwater resources. The study focuses on Conventional Development Scenarios, which assume mid-range demographic and economic projections, a global convergence in consumption and production practices, gradual technological advance, and no major policy changes. The report finds that such scenarios would bring a continuing deterioration of water conditions in those areas that are already water scarce and an extension of new water stress conditions in major places throughout the world. The report concludes with recommendations for how to envision and achieve a more sustainable path.

Contributors: Peter Gleick, Paul Kirshen, Gil Pontius, and Kenneth Strzepek

Water and Sustainability: Global Patterns and Long-Range Problems

This inquiry summarizes global water resources and patterns of use, applies indicators of water sustainability in order to identify areas of water stress, and examines prospects for water sustainability in the twenty-first century. It introduces a long-range conventional development scenario based on a vision of the future in which the values, consumption patterns, and dynamics of Western industrial society will be progressively played out on a global scale. The scenario helps clarify the constraints of a conventional picture of water development and provides a useful point of departure for examining alternative long-range scenarios and their implications for water and development policy.

Originally published in Natural Resources Forum 20, no. 1 (February 1996): 1-15,

Simulation of Water Supply and Demand in the Aral Sea Region

The Aral Sea, a huge saline lake located in the arid south-central region of the former U.S.S.R., is vanishing because the inflows from its two feed rivers, the Amudar’ya and the Syrdar’ya, have diminished radically over the past three decades. The loss of river flow is the result of massive increases in river withdrawals, primarily for cotton irrigation in the basins. This paper uses a microcomputer model, the Water Evaluation and Planning System (WEAP), for simulating current water balances and evaluating water management strategies in the Aral Sea region. The authors perform a detailed water demand and supply simulation for the 1987–2020 period. The analysis provides a picture of an unfolding and deepening crisis.

Originally published in Water International 17, no. 2 (1992): 55–67.