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Modelling tools determine future water availability and demand and have the potential to help planners and decision makers
Basin-level water availability in the context of climate change is a major concern for many regional planners and decision makers. While the extent of these changes is still not completely clear, scientists at ICIMOD predict that precipitation will increase during the monsoon but decrease during the winter, and that flooding will become more extreme, which will lead to problems with food production. In a region that is already facing increasing water scarcity and a growing population, the question of how much water will be available in the future and how this will interact with changing social and economic conditions is an important one.
In early 2013, the Koshi Basin Programme, in partnership with the International Water Management Institute (IWMI), completed a first of its kind study on future climate change scenarios, water availability, and possibilities for agricultural adaptation in the Koshi basin. As more data becomes available and the study is refined, it will be a valuable tool for future water resource planning.
To understand the water dynamics at play, the research team applied the Soil and Water Assessment Tool (SWAT), a basin-level hydrological model that helps to determine future water availability scenarios through assessing data on precipitation, surface runoff, and groundwater and river flow. The model also helps to determine the sources of a river’s flow – whether from precipitation, underground, or melting snow and glaciers – which is useful information for water resource planners and decision makers.
Using SWAT output data, the research team developed an innovative approach that integrated this data with the Water Evaluation and Planning (WEAP) model to assess future water availability until the middle of the century. Using input from the SWAT model, the WEAP model is able to estimate current and future water demands for different sectors, including domestic, agricultural, industrial, and hydropower sectors. Most importantly, WEAP can calculate unmet water demand and help decision makers understand the impacts of upstream developments in downstream communities.
The results of these two models showed that the available water in the Koshi basin is largely untapped: only 7% is currently utilized. These results suggest that there is great potential to use water from the Koshi basin for economic and industrial activities in the future, and that current issues around water scarcity largely stem from a lack of investment. Additionally, data also suggested that the Koshi River can generate 37 times more energy than the amount of energy that Nepal annually imports from India. This information can help planners make decisions about the construction of hydropower infrastructure.
The output produced by these two models will aid individuals who work in the Koshi basin in making plans for the future. Later in 2015, the Koshi Basin Programme will hold a workshop for government officials on how to use this data in their work. While this initial study has produced information primarily about water availability on the basin-level, the team is working to refine the models so that there is data available for the local-level as well. Local-level data on water availability is valuable for communities working to better manage their resources. ICIMOD’s hope is that a better understanding of water resources will make future planning in the Koshi basin a little bit easier.
Bharati, L; Gurung, P; Smakhtin, V; and Jayakody, p (2014) ‘the impact of climate change on water resources development in the koshi basin, nepal’. mountain research and development 34 (2), 118-130
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