APPLICATION OF DISTRIBUTED SENSITIVITY ANALYSIS TO A MODEL OF TURBULENT OPEN-CHANNEL FLOW IN A NATURAL RIVER CHANNEL

Sensitivity analysis is a widely applied tool used to investigate the predictions of numerical models of environmental processes. This paper illustrates the importance of undertaking a sensitivity analysis that considers the spatially distributed nature of model predictions, rath er than simply assessing the sensitivity of one or more model paramete rs that are assumed to represent the distributed behaviour of the syst em. A spatially distributed sensitivity analysis is applied to the out put from a distributed model of turbulent river flow, used to simulate the flow processes in a natural river channel bifurcation. Examples a re provided for an input parameter which illustrates the importance of sensitivity analysis with respect to model assessment and error analy sis. The distributed nature of the analysis suggests the importance of spatial feedback in environmental systems that more traditional appro aches to sensitivity analysis cannot reveal.