Modelling soil erosion and runoff for a super typhoon event using PCRaster

Abstract

A physical model for soil erosion and runoff was created for Alimit River Sub-watershed, using PCRaster Software. Manning's equation was used to model surface runoff velocity and Rose’ and Freebairn’s Equation was used to compute for sediment concentration. Event-based rainfall, saturated hydraulic conductivity, land use map, and digital elevation model were used as input for the model. Close correspondence was observed between the measured and predicted values for both streamflow and mass of eroded sediments. It was observed that vegetation played a significant role in reducing eroded sediments and choosing the correct Manning's Roughness Coefficient for various land use/ land cover is of utmost importance. Furthermore, in the absence of soil data, land use/ land cover or NDVI (Normalized Difference Vegetation Index) can be used as basis for the hydraulic conductivity of the soil.