A GIS-based Regional Scale Analysis of Urban Water Balance with an Aquifer-based Water Supply

A significant challenge in urban development is balancing water demand and supply given a growing population. In an aquifer-based water supply system, addressing water scarcity must consider urban hydrology, including maintaining groundwater levels and the interactions among elements of the water cycle. A Geographical Information System-based Python simulation of urban water balance was created to estimate the components of the water cycle in a region over time. The analysis includes changing land cover and the resulting change in the volume of aquifer extraction, wastewater treatment and disposition over time. The simulation models the basic elements of the water cycle, e.g., evapotranspiration, infiltration, and runoff, which are used to estimate impact as well as evaluate alternative water specific strategies. The simulation uses readily available water supply and treatment volumes, land cover and weather data, and pervious surface analysis to calculate outcome variables. The simulation spatial unit of analysis is a parcel, typically over a scale of a county, and the time step is daily, over multiple years. Parcel level data used includes metered water use, soil characteristics, and impervious surface area; weather input data includes precipitation and variables needed to calculate potential evapotranspiration; and regional-level data includes wastewater treatment and waste water disposition.