Estimating Lake–Groundwater Exchange Using Hourly Water Level Fluctuations in Central Florida

With mounting anthropogenic pressures on groundwater supplies, practical methods for quantifying lake–groundwater exchange are critical for water resources management. This is particularly important in karst environments where surface–groundwater connectivity is often high. The White method uses nighttime water level fluctuations to estimate groundwater flux. While the White method has been applied to flooded wetlands, published lake applications are rare. This study evaluated a modified White method for estimating leakage at 28 karst lakes in Florida. The method was modified to include evaporation correction, with both nighttime and all-day approaches evaluated. Using the nighttime correction approach, average annual groundwater flux (leakage) ranged from −2.4 to +1.9 m/y, with a mean of −0.5 m/y (negative indicates lake outflow). Without nighttime evaporation correction, leakage estimates would be erroneous by an average of −0.7 m/y. The results showed no significant difference from 138 leakage values compiled from previous studies that used diverse methods. The modified White method requires special attention to evaporation, filtering criteria, and hydrogeologic context. Overall, the method provides a useful complementary approach to other methods for estimating long-term annual lake–groundwater exchange with comparatively minimal data requirements.