The changes in both climate and land cover have some impact on water resources. Dengkeng watershed, mostly located in Klaten district of Central Java Province. Dengkeng River as one of the raw water source of agriculture and drinking water of society, besides as main water body in the drainage system. Climate change and land use directly affect land use patterns, water availability, flood control performance, local social and economic development, and so on. Therefore, studying the impacts of climate change and land use becomes very important. The HEC-HMS model is used in this study. The observed discharge data used AWLR data of Paseban with period 2005-2017, climate data used nearest post data with observation period 1979-2014. While changes in land use were used data in 1990, 2000 and 2011. The results of the analysis on climate change showed an increase in rainfall both monthly rainfall and maximum daily rainfall. While land use changes can be reviewed on the watershed hydrological parameters, one of which is the change of Curve Number (CN). An increase in CN value has an impact on increasing runoff. However, if viewed against the availability of water, then there is a trend of decline.