MODELING THE EFFECT OF LANDUSE CHANGE ON HYDROLOGIC RESPONSE OF A SEMI URBANIZED WATERSHED USING A PHYSICALLY BASED DISTRIBUTED MODEL

Recent increases in landuse change, in the Hill country, due to urbanization has resulted in increases in intensities of flooding. Landuse change affects runoff responses of watersheds. Understanding impacts of landuse change on watershed runoff responses requires rainfall–runoff models that can effectively simulate the complex hydrologic and hydraulic processes in a landscape. The objective of this work was to investigate the impacts of landuse change on surface runoff responses of the Leon Creek watershed, a 538 km² sub-watershed within the San Antonio river basin, with a typical Texas Hill Country landscape. A physically based distributed model: Gridded Surface Subsurface Hydrologic Model (GSSHA) was used to simulate runoff from the watershed. Precipitation data, from the Multisensory Precipitation Estimator radar products (MPE), were used for model calibration and validation, considering the effect of landuse change. Results showed that the landuse change has significantly altered the physical soil hydraulic properties (e.g., infiltration rates) that govern the hydrological processes in the watershed.