Aquifer-scale mapping of injection capacity for potential aquifer storage and recovery sites: Methodology development and case studies in Minnesota, USA

Study Region. Two areas in Minnesota, USA: Buffalo aquifer in Clay County and Jordan aquifer in Olmsted County. There are concerns about the long-term sustainability of groundwater resources in the two aquifers. Study Focus. Aquifer storage and recovery is an important tool for water resources management in various geographic and socio-economic contexts. However, practical guidelines regarding the assessment of injection capacity remain limited. In this study, we present a quantitative methodology which is based on the Theis solution. The methodology allows an efficient estimation of well-based injection capacity and generation of an aquifer-scale injection capacity map. We present a detailed workflow for applying the methodology and demonstrate its application to the two study areas. The tool developed in this study can be easily applied to other areas. New Hydrological Insights for the Region. The two study areas show significant spatial variability in injection capacity. In the Buffalo aquifer, the variability is mainly controlled by transmissivity, whereas in the Jordan aquifer, it is mainly controlled by maximum allowable hydraulic head change. Assuming an injection duration of one month and considering the 90-percentile value of the injection capacity at each site, we found that two and four wells are required to inject the volume of water equivalent to one month of domestic water requirements for the cities of Moorhead and Rochester, respectively.