Predicting Sea-Level Rise Impacts on Groundwater Quantity and Quality in Complex Hydrogeological Systems
摘要
Understanding groundwater dynamics in response to rising sea levels is crucial for effectively managing water resources, as projected sea level rise (SLR) will pressure public and agricultural freshwater supplies. This study examined the impacts of climate change-induced SLR on groundwater level and quality in South Florida using the customized SEAWAT model, the East Coast Surficial Model (ECSM). The model was calibrated and validated using daily groundwater level and total dissolved solids (TDS) data from 1985 to 2016 (2000s). Subsequently, the impacts of projected SLR under intermediate (0.4 m to 1.2 m) and maximum (0.5 m to 2.2 m) climate change scenarios on groundwater dynamics were assessed for three distinct periods: the 2035s (2017–2050), 2065s (2051–2080), and 2090s (2081–2100). The ECSM showed acceptable performance in simulating groundwater level and TDS with R2 values ranging from 0.5 to 1.0, although the model exhibited lower accuracy in predicting TDS at certain monitoring stations. Under the intermediate SLR scenario, groundwater level in 2035s is projected to increase on average by 25% across all land use types while the projected increase in the 2090s for agricultural, urban, and wetland is 150%, 200%, and 130%, respectively compared to the 2000s. However, under the maximum SLR scenario, in the 2035s, the groundwater level is projected to increase by 30%, 100%, and 50% in agricultural, urban, and wetland areas, respectively, with corresponding projected increases of 200%, 300%, and 175% by the 2090s. The results also revealed that saltwater intrusion, induced by the maximum SLR scenario, increased TDS levels in freshwater wells up to 35,000 mg/L in agricultural and urban areas, and up to 75,000 mg/L in wetlands. In the 2090s, under a maximum SLR scenario, saltwater intrusion could result in about 70% of Miami-Dade County underwater. In this period, freshwater coverage is projected to decline from 89 to 59% under the intermediate SLR scenario and to 20% under the maximum SLR scenario, while salinity levels could increase by 32% and 69%, respectively. Projected increases in groundwater levels and saltwater intrusion will have significant implications for freshwater availability and the environment in the region, both in the near and far future. This underscores the urgent need for proactive measures to safeguard groundwater resources and enhance the resilience of coastal communities facing the compounding impacts of climate change-induced SLR.