Effects of DEMs from different sources in deriving stream networks threshold values
Digital elevation model (DEM) is the most common surface topography data used to derive river network. DEM comes with different resolutions and can generate various topographic and hydrological features. This study investigates the effects DEM’s threshold values from different sources in deriving stream networks using Geospatial Hydrologic Modelling Extension (HEC-GeoHMS). DEMs of 30m resolution were acquired from SRTM, ASTER, and NEXTMap data. In addition, topographic DEM were derived from contour data of 20m interval to generate the stream network on the sub-basin of Jawi river, Penang, Malaysia. Subsequently, spatial comparison was made with the existing drainage networks derived from the Malaysian Department of Irrigation and Drainage (DID). The analysis reveals that the drainage network from SRTM with threshold values of 40 was closest to the referenced drainage. The result has signifies the most appropriate values for an effective stream threshold network to be considered suitable for future river sub-basin analysis.