EFFECT OF LAND USE CHANGE ON HYDROLOGIC PARAMETERS USING DHSVM

Abstract

The evaluation of effect of land use change on the hydrologic parameters was conducted using Distributed Hydrology Soil Vegetation Model (DHS V M) for the Rainy Creek watershed (Little Wenatchee river basin, USA) for two scenarios (i.e., vegetated and the non-vegetated). The SAGA-GIS was used for the input and output file processing in place commonly used Arclnfo software to test its viability and limitations. A few major steps included re-sampling of the digital elevation model (DEM) to achieve the desired resolution, model initialization, organization of the channel segments. After model calibration, the compilation of the model was launched albeit some errors and warnings. The troubleshooting of these errors helped in developing a better comprehension of the DHSVM software. The runoff in case of the vegetated watershed was found to be higher than the nonvegetated one, attributed to the type of soil (sandy loam) which dries out quickly. The evapotranspiration in the non-vegetated case followed six-monthly trend and was dominant in the summer period when the evaporation masks the transpiration. On the contrary, for the vegetated case, it exists throughout the year, less than the non-vegetated case in summer but more in winter due to the dominant transpiration. The seasonal variations of hydrological parameters like runoff, stream flow, ground water level, snow water equivalent, were also taken into account in drawing conclusions. The study of the effect of the initial soil moisture revealed that an increase in the soil moisture content is directly reflected in the observed runoff, more pronounced in the vegetated case than in the non-vegetated one. However, no direct variation was observed in case of evapotranspiration, channel interception and the final end of run storage.