Thornthwaite-Mather Water Balance Analysis In Tambakbayan Watershed, Yogyakarta, Indonesia

Depok sub-district in Yogyakarta is one of the most populous areas, which also develops rapidly. The Tambakbayan watershed, which includes Depok sub-district, has been seen as one crucial watershed in Yogyakarta. This study conducted a Thornthwaite-Mather water balance analysis in the watershed in order to understand its hydrology capability. The result of the study on three stream areas of the watershed (upstream, midstream and downstream) shows that the dry months begins in May-June and ends in September-October. August tends to be the driest month in the year with total deficit value reaches 179.2 mm. Still, the annual rainfall is higher than the annual evapotranspiration. The results also show that the lower area of the watershed has a lower capability to preserve water. However, the watershed still sufficient in providing the domestic water demand in the current state. Comprehensive water management plans suggested to be applied to protect the watershed from overstressing the water resources, especially in the downstream area.