SENSITIVITY AND UNCERTAINTY ANALYSIS OF A SEDIMENT TRANSPORT MODEL - A GLOBAL APPROACH

Computerized sediment transport models are frequently employed to quan titatively simulate the movement of sediment materials in rivers. In s pite of the deterministic nature of the models, the outputs are subjec t to uncertainty due to the inherent variability of many input paramet ers in time and in space, along with the lack of complete understandin g of the involved processes. The commonly used first-order method for sensitivity and uncertainty analyses is to approximate a model by line ar expansion at a selected point. Conclusions from the first-order met hod could be of limited use if the model responses drastically vary at different points in parameter space. To obtain the global sensitivity and uncertainty features of a sediment transport model over a larger input parameter space, the Latin hypercubic sampling technique along w ith regression procedures were employed. For the purpose of illustrati ng the methodologies, the computer model HEC2-SR was selected in this study. Through an example application, the results about the parameter s sensitivity and uncertainty of water surface, bed elevation and sedi ment discharge were discussed.