APPLICATION AND SENSITIVITY ANALYSIS OF PROCESS-BASED EROSION MODEL GUEST

As long-term measurement of erosion is expensive, models are required to predict spatial and temporal variation in erosion accurately for va rious land uses and to develop suitable practices for soil conservatio n. Details of the steady-state, process-based erosion model GUEST are presented with emphasis on the behaviour and sensitivity of the model to a fundamental erodibility parameter J. The model is developed to in terpret temporal fluctuation in sediment concentration from bare soil in single erosion events. It incorporates the simultaneous effects of rainfall and runoff and of deposition on sediment concentration. An ex ample of its application to temporal variation in sediment concentrati on for varying slopes and soil strengths show reasonable agreement bet ween the measured data and the limits of sediment concentration predic ted by the model. Sensitivity analysis indicated the model to be most sensitive to land slope and a defined sediment characteristic called d epositability, but not as sensitive to frequency and dimensions of ril ls.