Hindcasting multidecadal predevelopment groundwater levels in the Floridan aquifer

Area of Science:

• Hydrogeology
• Climate Science
• Statistical Modeling

Background:

• Long-term groundwater records are scarce, hindering understanding of aquifer dynamics.
• Distinguishing natural cycles from anthropogenic impacts (pumping, climate change) is challenging.
• Predevelopment benchmark groundwater conditions are essential for sustainable management.

Purpose of the Study:

• To develop and test a method for hindcasting multidecadal groundwater levels using limited data.
• To examine the temporal evolution of climate and pumping impacts on aquifer systems.
• To quantify the contribution of pumping to groundwater level declines.

Main Methods:

• A wavelet-aided statistical model was developed, incorporating rainfall, evapotranspiration, and pumping stresses.
• The model was validated using split calibration-verification and historical drought/wet periods.
• Hindcasting provided 110 years of monthly groundwater level data for analysis.

Main Results:

• Groundwater withdrawals account for 30-70% of observed declines since the 1960s.
• Hindcasting revealed a significant increase in the frequency of critical low groundwater levels from 1960-2015 compared to 1904-1959.
• At Site 1, climate change shortened the return period of critical low levels by 3.9 years, and pumping by 2.2 years.

Conclusions:

• The hindcasting approach effectively reconstructs historical groundwater levels and impacts.
• Both climate change and pumping have substantially increased the risk of critical low groundwater levels.
• Understanding these combined impacts is crucial for effective water resource management and planning.