The effects of DEM specification on watershed model in Mataram City, West Nusa Tenggara Province

Abstract

One of data resources for hydrologic modelling is Digital Elevation Model (DEM). In hydrologic modelling, watershed delineation is an important step to create boundary of inundation area, so that DEM plays a significant role in watershed model. Nowadays, there are many sources of DEM data available in Indonesia that was provided by Geospatial Information Agency (BIG), including LiDAR and DEMNAS (National DEM). Based on its resolution, DEMNAS is classified as data for medium scale mapping, while LiDAR is used for large scale mapping. For hydrological modelling, medium scale data has been widely applied, while the large-scale hydrological modelling is still limited. The availability of large-scale data is quite large, including the City of Mataram, is a good source to examine its effect for hydrological modelling, so this research is conducted to see the effects of DEM sources, namely LiDAR and DEMNAS, for watershed model generation. Analysis is conducted by comparison to existing official watershed in that area. From seven watersheds, LiDAR produce better geometry in four areas, while DEMNAS is better in the rest. This research is expected to support a policy relating hydrological modelling at large scale.