Improving the assessment of wetland needs in water management


Improving the assessment of wetland needs in water management: Adding environmental flows to Water Evaluation and Planning (WEAP) system models

In an increasingly complex world, with rising population, rapid social and economic transformation, ever increasing demand and climate change, the proper planning and management of water resources is no easy task. Water resource planners are required to make decisions in relation to a myriad of issues in a complex, constantly changing and highly uncertain environment. They must balance the needs of different stakeholders (including agriculture, energy, domestic and environment sectors) with conflicting interests and they must safeguard resources and protect the environment, including wetlands, for future generations.

In recent years, a large number of computer models have been developed to assist water resource managers. By processing and modelling large amounts of digital data, a complicated water system, such as a river basin, can be simulated and the consequences of different management options and different possible interventions can be predicted before making changes on the ground. Models provide water resource managers new insights on best practices and more sustainable approaches.

The Water Evaluation and Planning (WEAP) system, a water resources modelling tool, developed by the Stockholm Environment Institute (SEI), is at the forefront of water resource modelling and is used extensively around the world. One of the latest enhancements to WEAP is an improved function to estimate and model environmental flows.

The method used in this new function is the Global Environmental Flow Calculator (GEFC), developed by the International Water Management Institute (IWMI). The method ensures that natural flow variability is preserved in the estimated environmental flow time series. The environmental flow requirement can be calculated for several categories of aquatic ecosystem protection (i.e. different environmental management classes) ranging from "largely natural" to "severely modified". The greater the degree of protection the more water is needed for ecosystem maintenance and the more flow variability needs to be preserved. Model simulations enable water resource planners to evaluate environmental flow requirements within the broader water management context of a basin and to determine the implications of upstream water resource development on flows going to downstream ecosystems.

The method is a relatively simple "low-confidence" approach, which must be followed-up with more comprehensive studies. However, it is a significant first-step in improving water resource models. It is important because it will increase awareness of environmental flows amongst water practitioners, policymakers and other decision-makers. Furthermore, it can be used in developing countries where flow and ecological data are scarce. As such it represents an important contribution to the protection of wetlands worldwide.

More information on WEAP and the GEFC is available at and

[This  article has been provided by Matthew McCartney, Principal Researcher at IMWI,  the International Water Management Institute (one of Ramsar's five  International Organisation Partners). Matthew represents IWMI on the  Convention's Scientific and Technical Review Panel.]

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