Most catchments in the developing world are ungauged due to the high cost of instrumentation involved and are therefore not monitored. However, lack of data from these catchments can not be an excuse for lack of proper management and hence data from these catchments is still needed for their management as well as design of structures in these areas. This book illustrates how direct runoff and sediment yield can be estimated in an AgNPS model-GIS link. A case study of the river Njoro catchment in Kenya is used and the results show a possibility of using the method in cases where in-situ measurements are lacking, so long as the model input parameters are accurately determined. Professionals in hydrology, environment and engineering fields or anyone else who may be involved in hydrological modelling will find this book useful.