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Evaluating uncertainty in modelled sediment delivery in data-sparse environments: application to the Mae Chaem Catchment, Thailand

DAVID A. POST & MICHAEL G. HARTCHER

CSIRO Land and Water, Davies Laboratory, PMB PO Aitkenvale, Townsville, Australia

david.post@csiro.au

Abstract A sediment source, transport, and deposition model known as SedNet was applied to the Mae Chaem Catchment in Thailand in order to determine the dominant sources and sinks of suspended sediment in that catchment, and to examine the uncertainty in model predictions. The SedNet model produced a significant range of results where a range of cover factors, as well as spatially variable and constant hillslope delivery ratios were tested. The results indicate that the main source of uncertainty is due to the uncertainty in model input parameters, particularly in the selection of appropriate ground cover factors. This uncertainty can be reduced through better representation of ground cover using a combination of ground truthing and remote sensing. Conversely, reductions in uncertainty in the value of the hillslope delivery ratio can only be achieved through extensive fieldwork.

Key words sediment erosion and deposition; SedNet model; Thailand; uncertainty analysis

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