ESTIMATING INJECTION CAPACITY OF WELL-BASED MANAGED AQUIFER RECHARGE SITES

Managed aquifer recharge (MAR) has proved an effective method for securing water resources in various geographic and socio-economic contexts. As a result, water management agencies around the world are showing an increasing interest for MAR technologies. However, practical guidance regarding how to identify suitable MAR sites remains limited. In this contribution, we discuss a simple method to estimate well-based injection capacity. The method relies on the Theis solution of hydraulic head response to pumping. Based on this method, we conduct a theoretical analysis of the influence of the controlling factors of well-based injection capacity through a comprehensive sensitivity analysis. The results show that injection capacity is linearly related with the maximum allowable head change, and almost linearly related with transmissivity and pumping duration. Determining transmissivity is thus critical for injection capacity estimation. In contrast, injection capacity is little sensitive to storativity and well radius. Hence, the uncertainties on these parameters may not substantially affect the results. We then discuss the practical use of the proposed method for mapping well-based MAR suitability at regional scale. We present a case study that applies the proposed method to the Buffalo aquifer in northwestern Minnesota, USA. We present a spatial map of injection capacity and the influence of aquifer heterogeneity and groundwater level fluctuations on the results will be discussed. This study demonstrates the value of the proposed approach to address both theoretical and practical questions about well-based injection capacity. We envision to extend this work to also consider water quality issues for MAR suitability estimation.