Identification of priority areas for sediment yield reduction by using a GeoWEPP-based prioritization approach

Abstract

Sedimentation has been causing both onsite and offsite damages around the world. In this context, watershed prioritization allows decision-makers to implement management strategies for reducing sediment yield. So, this study aimed to determine the subwatersheds that produce the maximum amount of sediment for reducing sedimentation in a watershed. We used GeoWEPP, Geo-spatial interface for Water Erosion Prediction Project (WEPP) model, to predict sediment yield in the watershed. In order to run GeoWEPP easily and reliably, the watershed was divided into 85 subwatersheds. Sediment yield was found to be 5.13 tons ha− year−for the whole watershed. In order to produce a sediment risk map in ArcGIS, values from 0 to 1 were assigned to the sediment yield values of each subwatershed by using min-max normalization method. The obtained values were divided into 5 risk classes. According to this map, 42% of the study area was subject to very low sediment risk, while 28%, 12%, 7%, and 11% of it were subject to low, moderate, high, and very high sediment risk. When the sediment yield amount of the risk classes was investigated, very high sediment risk class accounted for 54% of total sediment yield in the watershed. These results revealed that a small part of the watershed contributed a disproportionate amount of the total sediment yield. Consequently, the GeoWEPP-based prioritization approach can help decision-makers design and implement effective soil and water conservation practices to reduce sediment yield in the regions where human and financial resources are limited.