A Modified LAPSUS Model to Enhance the Effective Rainfall Estimation by SCS-CN Method

Abstract

In this study, LAPSUS model is modified to enhance the effective rainfall estimation<br><br>by SCS curve number method. The LAPSUS model calculates discharge based on<br><br>effective rainfall and routs it towards lower neighbouring grid cells following the multiple<br><br>flow direction principle. Then, the sediment transport capacity and sediment transport rate are<br><br>calculated in each grid cell. Finally, erosion or sedimentation is calculated by comparing the<br><br>sediment transport rate with the sediment already in the transport of each grid cell. The amount<br><br>of rainfall, curve number, convergence factor, discharge exponent, slope exponent, erodibility<br><br>factor, and sedimentation ability factor are inputted to the application page of the modified<br><br>model that was created in the C++ programming. The outputs of the model are runoff and<br><br>erosion maps in ASCII format. Evaluating performance of the modified model showed a high<br><br>accuracy of its results. The value of the coefficient of determination (R2) calculated 0.99 for<br><br>runoff and 0.97 for erosion. The Nash-Sutcliffe efficiency was 0.96 for runoff and 0.97 for<br><br>erosion. The value of the precision index calculated 0.81 for both runoff and erosion. Also, the<br><br>nRMSE calculated 3% for both runoff and erosion. The result showed that the modified model<br><br>capable to estimate the runoff and erosion on a landscape in a micro sub-catchment scale.