A probabilistic management system to optimize the use of urban groundwater

Urban groundwater is an underused resource mostly due to the perceived risk of contamination; conversely rural groundwater is being over-exploited. To enable urban groundwater to be utilized effectively a probabilistic water management tool has been developed. The management tool combines three models to identify the best use for water pumped from a user-defined location. The probabilistic catchment zone model determines the spatial distribution of the probability that water originating from a given point in the aquifer reaches the pumping well. The land-use model then identifies the potential contaminant sources in this region from a large set of GIS-based coverages and databases. The contaminant source data are passed to a pollution risk model that calculates the probability distribution for the concentration of a contaminant at the pumped borehole. Initial model validation using contaminant concentrations from two sites shows the model fits the available field data. These case studies show there is risk from chlorinated solvents but little risk from the BTEX compounds.