WATER BUDGET ASSESSMENT UNDER RAPID URBANIZATION IN YOGYAKARTA, INDONESIA USING A DISTRIBUTED WATER BALANCE MODEL

: Rapid urbanization has increased the challenge of freshwater provision for the urban population. Modelling water balance can help visualizing the occurrence in a hydrological system due to urbanization that is beneficial for future water-resource management. A hybrid distributed monthly water balance model adopted from Xinanjiang model and TOPMODEL by (Chen et al. 2007) has succeeded to simulate the distributed water storage in a catchment area and applied to the water resources change assessment by districts in peri-urban area of Yogyakarta City, Indonesia. The hybrid model was modified to include water uptake in urban area. The optimized model estimated monthly river discharge with R = 0.77. The model demonstrated the saturation distribution change by the intensified water uptake in expanded urban area especially in dry season. The model simulation could point out the sensitive districts of which water storage possibly decrease caused by the urbanization progress.