SENSITIVITY ANALYSIS OF SIMULATED CONTAMINATED SEDIMENT TRANSPORT

A simulation analysis of contaminated sediment transport involves mode l selection, data collection, model calibration and verification, and evaluation of uncertainty in the results. Sensitivity analyses provide information to address these issues at several stages of the investig ation. A sensitivity analysis of simulated contaminated sediment trans port is used to identify the most sensitive output variables and the p arameters most responsible for the output variable sensitivity. The ou tput variables included are streamflow and the flux of sediment and Cs -137. The sensitivities of these variables are measured at the field a nd intermediate scales, for flood and normal flow conditions, using th e HSPF computer model. A sensitivity index was used to summarize and c ompare the results of a large number of output variables and parameter s. An extensive database was developed to calibrate the model and cond uct the sensitivity analysis on a 6.2 mi(2) catchment in eastern Tenne ssee. The fluxes of sediment and Cs-137 were more sensitive than strea mflow to changes in parameters for both flood and normal flow conditio ns. The relative significance of specific parameters on output variabl e sensitivity varied according to the type of flow condition and the l ocation in the catchment. An implications section illustrates how sens itivity analysis results can help with model selection, planning data collection, calibration, and uncertainty analysis.