Manatee Spring near Chiefland, Florida: Photo by Stewart Tomlinson, USGS
Problems
Water resource managers are faced with several problems and issues with respect to the availability of groundwater from the FAS including (1) groundwater depletion, (2) saltwater intrusion, and (3) migration of groundwater divides. The lack of a current, regionally extensive holistic numerical model tool which encompasses the physical boundaries of the FAS serves as an impediment to greater understanding, and hence management, of the Floridan aquifer system as a whole.
Benefits
Benefits of the Floridan aquifer system groundwater availability study include:
Revised regional hydrogeologic framework: A revised hydrogeologic framework of the Floridan aquifer system will replace the disparate local and subregional frameworks that have been developed since the Regional Aquifer-System Analysis (RASA) study (Miller, 1986) and that currently serve as an impediment to system-wide modeling. Publication of databases of hydrogeologic properties will be a valuable resource for current and future studies.
Development of a modern, system-wide, groundwater flow model: A modern groundwater flow model of the entire Floridan aquifer system does not exist. Development of such a tool will facilitate regional understanding of the aquifer system and could provide the platform for multi-state and multi-jurisdictional management of the resource. An additional benefit is that the model proposed as part of this effort will extend to the physical boundaries of the FAS and, therefore, allow for an internally consistent, holistic assessment of the driving forces of regional flow in this aquifer system. Therefore, this model will be the only tool capable of fully assessing divide migration at a regional scale and will allow for an objective third-party analysis where groundwater divide migration concerns are an issue.
Improved understanding of the groundwater budget: Independent and model simulated water budgets for the Floridan aquifer system will provide more highly resolved (in space and time) estimates of aquifer recharge, discharge (groundwater withdrawals, evapotranspiration, spring flow, baseflow), and changes in storage compared to existing system-wide estimates.
Assessment of the potential impact of sea-level rise: Saltwater intrusion in the FAS is of great concern; sub-regional studies in coastal Georgia and northeast Florida, as well as northwest Florida and west-Central Florida have been undertaken as a result of local salinization of public supply wells, however, to date (2015), there has not been a regional analysis of the potential for movement of the saltwater interface throughout the FAS. Recently developed software (i.e. Seawater Intrusion Package (SWI) for MODFLOW-2005; Bakker and others, 2013) now allows for the simulation of generalized movements of the interface and will provide insights into the regional dynamics of saltwater intrusion.
Assessment of the potential impact of future groundwater demand: Increased water demand coupled with the continued subregional approach to managing water resources in the FAS, has created the potential for local-scale water management operations to affect the location and movement of groundwater divides at the regional scale.
Assessment of the potential impact of climate change: The impacts of potential climate change may affect patterns of groundwater recharge, flow, and storage. The effects of these potential future stresses on the Floridan aquifer system will be assessed at the regional scale.
