Design of water reuse storage facilities in Sustainable Urban Drainage Systems from a volumetric water balance perspective

This paper presents a methodology for designing water reuse storage facilities as part of Sustainable Urban Drainage Systems (SUDS) in urban catchments. The method analyzes the whole water balance of the catchment. The contributions to the balance are irrigation and precipitation; the outlets are evapotranspiration, seepage and discharge to the conventional sewage system. The internal system variations are the volume of water to be locally reutilized and the soil water content variation. A cost function that includes the costs of irrigation, discharge to the conventional sewer system and reuse of water locally is proposed to estimate the optimum volume of water to be reused. This approach for SUDS design goes beyond traditional events-based perspectives oriented to damage prevention. This method conceives stormwater as a resource and seeks its optimal use through the design of SUDS. Several types of urban catchments were studied, and the results show that the proposed methodology can be applied either for simulating SUDS behavior in urban catchments or for estimating the optimum volume of water to be locally reused.