Effect of spatial resolution on runoff volume and sediment yield

Document Type : Original Article

Authors

1 Civil Engineering Department, Ph D Candidate M T C.

2 M. T. C., Egypt.

Abstract

Abstract
Raster-based Digital Elevation Models (DEM) is recently used for representing elevation surface in watershed modeling. As different resolution of elevation models could be available, this study investigates the impact of DEM resolution on volume of runoff and sediment yield for different rainfall events of the Bagoush watershed in northern coast of Egypt about 50 km east of Matrouh city. The Digital Elevation Model with spatial resolution of 30m and 12m were used for comparative examinations. By using GIS (Geographic Information System) software Arc-Hydro, a 30m and 12m DEM’s resolution are created to delineate the watershed and extracted the drainage pattern. The overall stream slopes and lengths are measured. The measured watershed parameters are used as input data for WASHMO model in order to get water inflow and sediment discharge also to generate runoff hydrograph and sedimentgraph. The results are compared with the aerial photo results which are considered as a basis of such work.The results of this study showed that DEM’s resolutions affects the watershed delineation, moreover the study showed that the volume of runoff for 12m and 30m DEM resolutions are differ than that aerial photo by approximately 31% and 39%, respectively. While for the sediment yield for 12m and 30m DEM resolution are differ by approximately 9% and 28% respectively for each rainfall events.

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