It is becoming acknowledged that water is likely to be the most pressing environmental concern of the next century. Difficulties in river basin management are only exacerbated when the resource crosses international boundaries. One critical aid in the assessment of international waters has been the Register of International Rivers a compendium which listed 214 international waterways that cover 47% of the earth's continental land surface. The Register, though, was last updated in 1978 by the now defunct United Nations Department of Economic and Social Affairs. The purpose of this paper is to update the Register in order to reflect the quantum changes that have taken place over the last 22 years, both in global geopolitics and in map coverage and technology. By accessing digital elevation models at spatial resolutions of 30 arc seconds, corroborating at a unified global map coverage of at least 1:1 000 000, and superimposing the results over complete coverage of current political boundaries, we are able to...

International River Basins of the World

This paper presents a water resources sustainability index that makes it possible to evaluate and compare different water management policies with respect to their sustainability. The sustainability index identifies policies that preserve or improve the desired water management characteristics of the basin in the future. This index is based on a previous sustainability index with improvements in its structure, scale, and content to make it more flexible and adjustable to the requirements of each water user, type of use, and basin. The Rio Grande transboundary basin is used as a case study demonstrating the use of the index. Tailor-made sustainability indexes are defined for water users in Mexico, the United States, the environment, and for meeting system requirements (international treaty obligations). Group sustainability indexes are calculated to summarize the results for groups of water users of each country, the environment, and the basin as a whole. Sustainability indexes by subbasins are calculated ...

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Sustainability Index for Water Resources Planning and Management

Advanced computer models are commonly used to simulate reservoir system's performance. If the number of possible management scenarios is large, it can be extremely difficult to follow related system's operation and get a valuable picture on its spatial and temporal behavior. The decision maker or analyst can be overburdened by quantity and complexity of information generated by model, particularly if system operation is repeatedly simulated for multiyear periods. Related problem is how to select the scenario with most desired long-term consequences. Possible approach is to use selected parts of model's output and re-interpret system behavior by means of certain performance indicators, create appropriate decision matrix and perform multi-criteria analysis to rank decision alternatives (scenarios). The paper proposes a methodology that includes: (1) multiyear simulations of system operation; (2) computing spatially and temporally distributed systemperformance indices such as supply reliability, resiliency and vulnerability; (3) unbiased entropy-based weighting the importance ofperformance indices; and (4) final ranking of scenarios by means of multi-criteria analysis. The number of scenarios and number of performance indices is not restricted, and to account for possibly large sets of scenarios, an ideal-point-distance multi-criteria method TOPSIS is suggested. Proposed methodology appeared to be confident and robust in proof-of-concept application in Brazil.

An Objective Multi-Criteria Evaluation of Water Management Scenarios

Properties of optimal hedging for water supply releases from reservoirs are developed and discussed The fundamental decision of how much water to release for beneficial use and retain for potential future use is examined analytically Explicit correspondence is established between optimal hedging and the value of carryover storage This more analytical view of hedging rules is useful for better understanding optimal hedging and simplifying numerical optimization of hedging operating rules The derivations suggest the frequent optimality or near-optimality of two-point hedging policies for water supply operations

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Optimal Hedging and Carryover Storage Value

Understanding performance measures of reservoirs

Reliability in water supply reservoir operation is commonly thought of as the probability of failing to achieve some target release. Here we explore two additional proposed descriptions of reservoir performance: the maximum shortfall from the target (system vulnerability) and the maximum number of consecutive periods of deficit during a record (system resilience). The larger the maximum shortfall, the greater the vulnerability. The shorter the maximum length of deficits, the more resilient the system. Using multiobjective mixed-integer, linear programming, the tradeoffs between reliability, vulnerability, and resilience are examined. It is found that as reliability is increased or as the maximum length of consecutive shortfalls decreases (resilience increases), the vulnerability of the water system to larger deficits increases.

Wai-See Moy

Papers

A Programming Model for Analysis of the Reliability, Resilience, and Vulnerability of a Water Supply Reservoir