Long-term Water Balance of an Inland River Basin in an Arid Area, North-Western China

Abstract: China, like many other countries in the region suffers from the water scarcity and problems of desertification and land degradation. One of the most useful approaches to deal with such a problem in the region is water balance study and analysis of different components involved to get an overview of the water supply and demand of the region so that engineers and policy makers can use that in their decision. Different hydrologic models have been developed for different conditions e.g. catchment size and data availability. Hydrologic Modeling System (HEC-HMS) among them is capable to simulate different catchment sizes with well detailed information as well as limited data availability. Geographic Information System (GIS) is also used as a useful tool to delineate sub-basins and extract terrain and physical characteristics of the region and associate them to the hydrologic model. Long term water balance for years between 1963 and 2001 was studied at Shiyang River basin, an inland catchment in Gansu province in western part of China. Calibration for the model could not be applied because of immense data limitation, though the model computes a fairly good estimation of water volume of the region which was applied in water balance equation. The hydrologic components e.g. water supply and demand of the region was determined and the trend of changes of the components were also presented for the study period. The study shows a good cooperation between GIS and HEC-HMS to apply for water balance study and gives a good estimation of component values despite limited data.