Using probabilistic well vulnerability criteria for a risk-based preventive drinking water safety concept

The most common concept to control the risk of drinking water contamination is the delineation of advection-based well-head protection zones. In 2006 Frind et al. extended this concept by introducing four intrinsic well vulnerability criteria that account for additional advective―dispersive transport information, such as dilution of peak concentrations through diffusion and dispersion. Our approach quantifies the uncertainty of well catchments and protection zones based on these advective―dispersive vulnerability criteria within a probabilistic framework. In order to account for uncertainty and to keep computational costs low at the same time, we combine Monte Carlo simulations with a temporal moment approach for model reduction. Our method allows stakeholders to take informed risk-based decisions in order to better control and manage the risk within their well catchments, which is necessary to develop complete risk management schemes as recommended by current Water Safety Plans.