An empirical model development for the sediment transport capacity of shallow overland flow: model validation

A sediment transport capacity model was developed specifically for shallow rain-impacted overland flow (Guy et al. 2009a) and calibrated (Guy et al. 2009b). The results of model validation exercises are presented here. Model tests using data collected in the present study indicate that sufficient data were obtained to characterise reliably transport behaviour within the ranges of the independent variables examined and indicate that model predictions are satisfactory. Tests of the model against previously collected data confirm this result, notwithstanding some differences in experimental conditions between previous and present studies. Empirical limits of validity of the calibrated transport model are determined from the results of model calibration and by comparison of model predictions with previous data. These analyses also suggest ways to refine the transport model, including conducting experiments using material with density intermediate between 1500 and 2650 kg m−3, using particles smaller than 0.1 mm diameter, examining higher transport rates to explore the limits of rainfall influence, and collecting additional data to confirm the transport threshold function proposed in the present study.