Progo Watershed Deliniation and River Network Analysis Using SRTM DEM and Contour DEM Hypsography of RBI 1: 25000

Watershed is a combination of waters and land areas where the boundary is topography of water separator. Watershed can be imagined as a sloping from upstream to downstream where rainwater that falls on topographic boundary will flow into river. The end of drainage system is a single outlet that boils down to larger body of water such as river, lake, or sea. Watershed can be formed based on the topography of a region. Topographic data is processed to Digital Elevation Model (DEM). DEM development can be utilized for the purposes of watershed characteristics analysis. DEM can be used for determination of watershed boundary and established river network. The characteristics of the watershed will affect hydrological behavior such as evapotranspiration, infiltration, and river flow. The result of the research shows the area of DAS based on SRTM DEM data is 218257.640 hectare, while based on RBI DEM data is 238714.236 hectare. The length of the main river Progo River based on SRTM DEM data is 133.874 Km, while based on data RBI DEM has a length of 134.689 Km. The combination of these two data produces the physical characteristics of Progo watershed quite well.