Phenomenological models of hydrologic processes in south Florida

The objectives of this study were to use existing hydrologic data to identify phenomenological models appropriate for describing key hydrologic processes in south Florida, and collect field data to develop improved process equations. Analyses of 3300 storm events within a 250-km2 study area in south Florida indicate that rainfall amounts and durations are typically correlated over distances on the order of 2 km. For 1-h duration storms, significant correlation exists for length scales on the order of 1 km, and for 24-h duration storms, significant correlation exists for length scales on the order of 10 km. Double-ring infiltrometer tests indicate that asymptotic infiltration capacities can be reasonably estimated from soil texture. Infiltration capacities are characterized by relatively rapid decay rates and typically approach a constant value within 10 minutes of ponding. Rainfall-recharge data indicate a linear relation between rainfall and recharge characterized by a specific yield of 0.26 and a threshold rainfall of 1 cm. Evaporation from the saturated zone during persistent dry periods can be described by a linear model in which the saturated-zone evaporation rate is equal to the potential evaporation rate for a depth of 1.4 m and decreases to zero at a depth of 2.5 m.