Human interference in the upper River Njoro catchment has led to the increased exposure of the land to\r\naccelerated erosion. An application that combined the capabilities of remote sensing, geographic\r\ninformation system (GIS) and agricultural non-point source (AgNPS) model was used to estimate peak\r\nrunoff rate and sediment yield from the upper River Njoro catchment. Remotely sensed Landsat\r\nThematic Mapper (TM) images were used to obtain land cover and associated AgNPS model input\r\nparameters. Other input parameters for the model were extracted from GIS layers using the agricultural\r\nnon-point source-integrated land and water information system (AgNPS-ILWIS) interface. Surface water\r\nquantity and quality data including peak runoff and sediment yield of selected storm events were\r\nobtained from two gauging stations, within the catchment. Base flow separation was done so that\r\nmeasured direct peak runoff rate and sediment yield generated by direct runoff could be determined\r\nand compared directly with the model simulated results. Simulated peak runoff rates in Upstream\r\n(Treetop) station were satisfactory with an EFF of 0.78 and a percent error of 4.1%. The sediment yield\r\nwas also reasonably estimated with an EFF of 0.88 and a 2% error. The downstream (Egerton) station\r\nresults were also satisfactorily predicted with peak runoff rate having an EFF of 0.69 and a 5.5% error of\r\nestimates, while the estimated sediment yield had an EFF of 0.86 and a 2.5% error.
Loading....