Evaluation of climate change and salinization impacts on water demand for irrigation. Case study in the Zeravshan River Basin.

Water use efficiency has been especially important under growing demand for the water resources. Human activity impact, population growth and increased competition have made water resources distribution one of the most important subjects in arid and semi-arid regions. In Central Asia, water distribution has not only food availability issue but also huge economic impact, as it threatens security of water resources availability and possibilities for development. Most of the rivers in the region are snow-glacier fed, originating in high mountain areas of one country, flowing and fully utilized in downstream areas of others. These rivers are heavily managed, over conflict from both sides on water consumption and thus confronting arguments over hydropower and irrigation usage. However, not only these issues affect water distribution but also water quality decrease due to salinization in downstream and most importantly impacts of climate change. Climate change will have significant impact over glaciers and snow melting process and human activity will accelerated them. In this study we evaluate salinity distribution along the river flow and impact of climate change to the water consumption, adaptation of unused saline waters is also assessed.

Through multi-model framework and field observation water resources requirements, irrigation demands and crop diversification were analyzed to address climate change impact and future water management nexus. Future climate impacts on water availability for agricultural crops in near and far future, salinity and its distribution has been assessed. Multiyear water observations were held to define main pollutant areas to investigate appropriate irrigation methods to maximize outcomes of the main crops. Current study suggests that river flow is decreasing and traditional irrigation strategies could not cover future irrigation requirements, by 10% and 15% in near and far future respectively. Better redistribution of the saline water through drainage and main channels should be addressed, including usage of such marginal waters in alternative strategies. Application of such waters in growing salt tolerant plants could become a good strategy in future, as they are not fully utilized now. The study was performed in the case study of Zeravshan river basin.