Evaluating Potential Impact of Short-Term Augmentation of Groundwater Production on Groundwater Levels in Tampa Bay Region

Abstract

Water supply management is challenging due to diverse stakeholders, conflicting objectives, increasing water demand, increasing regulation complexity, changing climate, and infrastructure constraints. To manage residual risk for water supply systems, utilities often apply water shortage mitigation plans to navigate through rare but extreme water shortage conditions before investing in an expensive new supply infrastructure. Some supply source augmentation strategies can be enabled through temporary reduction of regulatory constraints, e.g., groundwater production permits, that are protective of natural systems. Understanding the potential impact of pumping excursions on the groundwater level is important before implementing such management strategy. This study examines the resilience of water levels in the surficial aquifer system to temporarily increased groundwater pumping above a permit limit in the Tampa Bay region, located in west central Florida. Two major modeling tools were used, including the calibrated Integrated Northern Tampa Bay (INTB) model that dynamically couples hydrologic simulation of uplands and water bodies with groundwater and Unit Response Matrix (URM), which estimates groundwater level changes at monitoring wells due to pumpage changes at production wells. Both recovery time and maximum groundwater level changes are investigated. Results reveal that the median recovery time to preexcursion conditions for surficial aquifer in the study area is within 1 year for nearly all investigated scenarios. This indicates groundwater production excursions can serve as an attractive measure to mitigate severe water shortage conditions with no long-term adverse impacts to natural systems. Implication of this is a potential deferment of significant investment in infrastructure in the study area with the use of an effective water shortage mitigation plan to manage residual risk of the water supply system.