Modelling the impact of water reuse strategies on hydrologic flows in the Blackwater and Chelmer catchments, UK.

Wastewater reclamation and reuse at various scales is an important resource management toolin many regions of Europe and is coming under increasing scrutiny in the UK. However, the impact of reusestrategies on hydrologic flows, particularly during dry periods, is poorly understood and yet crucial to thedevelopment of sustainable resource management policies. In this paper we summarise the integrated modelsused for the simulation of such strategies (river flows, soil hydrology, aquifer dynamics and waterdistribution) and describe how water demand ‘profiles’ can be incorporated into a distribution matrix tosimulate recycling scenarios and demographic changes, and how both inter-catchment transfers and waterimportation schemes are implemented within the model. We highlight the strengths and limitations of boththe modelling methodology and its application in this context, noting in particular how the approach supportsconsideration of new infrastructure configurations, and the simulation of spatially variable consumerbehaviour and other regional development and land-use plans. Simulation outputs show that low to mediumuptake rates of in-house water recycling devices (andlt;30%) are unlikely to have significant impacts oncatchment water balances. Conclusions suggest that the connectivity of the hydrological system in theChelmer and Blackwater appears to provide robustness in the face of water recycling schemes, but regionalschemes, which do not transfer water across catchment boundaries have the potential to adversely influenceboth hydrological flows and river water quality.