Evaluation of the Effect of Varying Digital Elevation Model (DEM) Resolutions on Hydrologic Model Performance of a Tropical Watershed

Remote sensing has been used in the industry to understand present and future scenarios and promote better management practices of different systems. Hydrologic modeling as a tool can be used to represent and predict watershed behavior considering the different changes in an area due to continuous developments such as urbanization and population growth. However, the accuracy and performance of hydrologic models largely depends on the quality of input that will be used, thus the need to establish the relationship between input data and model performance is very important in coming up with decision-support information that will be beneficial in the management of such systems. This study aimed to evaluate the effect of varying Digital Elevation Model (DEM) resolutions on the hydrologic model performance of a tropical watershed in terms of statistical parameters namely the Nash-Sutcliffe Efficiency (NSE) and Percent Bias (PBIAS). A hydrologic model of the Davao River Basin was set up using HEC-HMS and was calibrated and validated before comparing the effects of varying DEM resolutions. Results reveal that as the DEM resolution gets larger, it leads to lower model performance due to less fine resolutions of elevation detail, flow directions, and flow accumulations that define streams and drainage lines. These findings can help hydrology modelers in choosing inputs from remote sensing to improve model performance and increase the reliability of their models that can serve as baseline information for policy making for better watershed management.