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Geographical Information System (GIS), slope information, Sediment yield, AGNPS model, tropical catchment


This study compares the effects of slope information derived from three GIS software on sediment yield as estimated using AGNPS model. The three GIS software are IDRISI for Windows, ERDAS Imagine and ArcView. The results of the study clearly demonstrated that the different software produced different slope information. The deviations were considerable when the comparisons were based on raw slope values. The maximum slope values generated by the software differed by as much as 61 percent. Not only the software produced different slope values, the locations where the maximum slope occurred were also different. These differences in slope information subsequently impacted the estimates of sediment yield using the AGNPS model. While the maximum slope information differed only by 1.6 times, the maximum sediment yields generated by the difference software varied by as much as 12.7 times. This strongly indicates that the use of different GIS software in environmental modeling might lead to different decision making and management strategy.