Application of the Monte Carlo Technique to Riverine Sand and Gravel Extraction - Analysing Risk in Complex Environmental Systems

摘要

River Management challenges arise due to a high level of uncertainty associated with fluvial systems, which respond to random and highly variable processes, in complex and unpredictable ways. This problem is compounded by the lack of understanding of how fluvial and landscape erosion processes interact, and vary in space and time in a catchment. The probability of different outcomes occurring for river management problems can be addressed using a Monte Carlo framework, supported by expert knowledge of fluvial hydraulics, sediment transport and geomorphology. In this example, the Monte Carlo method was used to assess the sustainability and environmental risks associated with a proposed riverine sand and gravel extraction for three different scenarios, within the context of the overall catchment sediment budget. Results demonstrated how the replenishment of excavated river bed material would occur within given time frames with some confidence, and the increasing environmental risk with resulting from additional extraction. Finally, sensitivity analyses showed that a sound understanding of a small number of key variables and parameters could significantly improve confidence in the model prediction.