Freshwater cooling injection to mitigate saltwater intrusion and support sustainable groundwater management

Abstract

This study examined the influence of thermal forcing on saltwater intrusion into nearshore aquifers (SWI) in the context of sea level rise due to climate change and continued groundwater withdrawal due to increasing demand. The study used the SEAWAT code to test two case studies: the Henry problem as a benchmark and the Biscayne Aquifer, Florida, USA, as a real case. Simulations were performed for the base case, sea level rise (SLR), and inland groundwater recharge reductions. A new management method was proposed for mitigating SWI in nearshore aquifers using the Abstraction of saline water, Desalination, Cooling the desalinated water, and Injection into the aquifer (ADCI) strategy. The method was tested with different freshwater temperatures of 25, 20, 15, 10, and 5 °C. The results showed that freshwater recharge in coastal regions is sensitive to the thermal regime, resulting in the attenuation of SWI. The results of this study are important for the sustainable management of groundwater resources in coastal areas to meet increasing water demands. The Biscayne salt repulsion reached +9.80 %, +10 %, +10.20 %, +10.30 %, and + 10.50 % for changing the injection recharge by 25, 20, 15, 10, and 5 °C. Future planning, design, and development of SWI mitigation measures should consider thermal regime effects. In addition, a cost–benefit analysis for this method using 3D models is needed to determine the feasibility and economic aspect of cooling water supply compared to current techniques.