Uncertainty Analysis of an Integrated Water System in Southern England: Exploring Physical and Socio-economic Uncertainties

Abstract: Climate change risk assessment of water resources is fraught with uncertainty. Such uncertainty is not only the accumulation of individual uncertainty components, but also the results of intricate interactions amongst the physical environment and the socio-economic system. There is often a mismatch of model representation of these two systems: while uncertainty of physical factors has often been described using quantitative methods, socio-economic factors have largely been qualitative. In our drought assessment case study, we evaluate uncertainty in the physical factors and demand responses in the context of climate change. In particular, we focus on structural uncertainty of the supply component and data uncertainty of the demand component. To explore structural uncertainty, a model of fine scale that has nodes representing real supply and demand sources was used as a reference model; another model at the water resource zone scale was used as an emulator to reflect information loss if a coarser spatial resolution is used. The input data are the UK Climate Projections 2009, 1989-2011 historic demand and 1961-1990 historic climate data. The main model output of interest is failure of supply. We found that uncertainty from the hydrological model contributes a high uncertainty margins to the final model results; in this case study it is more influential than uncertainty from either projected climate change or demand growth