A resource for modeling the inundation areas of prospective dams on the Irrawaddy, Salween, Mekong, and Red River basins.

Dam construction in mainland Southeast Asia has increased substantially in recent years. Whereas dams have in many cases provided significant value in terms of electricity production, drought and flood risk reduction, and improved crop production opportunities, they are also responsible for extensive regional impacts including alterations to water regimes, the loss and degradation of natural forests and biodiversity, and reductions in soil and water quality. A recent regional needs assessment and other stakeholder requests have pointed to the need to better understand both the positive and negative impacts of existing and potential dams.

This tool is one response to that need. SERVIR-Mekong has refined an outline tool for modeling the inundation of proposed dams. The tool has been used to compile a dataset of the extent of all existing and planned dams along the region’s large, transboundary rivers. The tool, which requires no proprietary software to access and use, can model the inundation area of hypothetical dam location along with a dam height. The tool uses this information and a digital elevation model to simulate the corresponding inundation area (reservoir). The output of the tool is a polygon feature of the estimated area of inundation (reservoir).


Launch Reservoir Mapping Tool

Application Purpose

The tool was generalized and published into a user-friendly responsive online GIS web application so that any interested users can explore the likely impacts of hypothetical dams, from any browsers and any kind of smart devices. This information is often extremely valuable for a number of applications that stakeholders in the region identified during and since SERVIR-Mekong’s Regional Geospatial Data and Technology Needs Assessment. These include: understanding and estimating impacts to river ecology, analyzing the downstream risks of dam failure, understanding opportunities in the context of drought and flood management, estimating land cover and land use change, evaluating carbon emissions, and assessing the potential impacts of dams on communities.

Application Uses

The primary use of the tool to date has been to produce key inputs for an ongoing effort to compile the first comprehensive collection of dam inundation areas on transboundary rivers in the Lower Mekong Region. That data product will include both the areas of existing and proposed dams. Given a number of needs expressed by stakeholders in the region, it is hoped that specific uses will be evaluating cumulative impacts of dams on land cover and carbon emissions, preliminary alternative scenario analyses for planned dams, and application in the risk assessment contexts mentioned above.

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