Rainfall-Based Management Plan for Water Conservation Area 3A in the Florida Everglades

The South Florida Water Management District (District) is responsible for managing water resources in a 46,439-square-kilometer (17,930-square-mile) region. The area prominently contains Lake Okeechobee, the second largest freshwater lake in the United States, and the internationally recognized Everglades wetlands. The Water Conservation Areas (WCAs), major components of the Everglades, supply water to Everglades National Park and the lower east coast of south Florida. They consist of WCA-1, 2A, 2B, 3A, and 3B. WCA-3A, the largest of the five WCAs, covers a 198,727 hectares (491,049 acres) wetland area and is situated immediately north of the Park. The WCA-3A Rainfall-Based Management Plan is used to operate water control structures that maintain desired water levels in WCA-3A. The objective of the plan is to restore a more natural hydroperiod and hydropattern in Northeast Shark River Slough and Everglades National Park A model is being used to define flow targets for the operation of five water control structures (S-333 and S-12A, B, C, and D) along the southern boundary of WCA-3A subject to upstream hydrologic conditions and downstream hydrologic and ecologic constraints. This paper details the mathematical model used to compute target weekly flow volumes to be released from WCA-3A. The model uses weekly rainfall data from ten rain gauges, weekly evaporation data from three pan evaporation gauges, and weekly average stage data from three water level gauges. The performance of the model, i.e., computed flows, was evaluated from 2002–2005, when weekly rain gauge data were substituted by area-weighted averages of weekly gauge-adjusted NEXRAD (Next Generation Weather Radar) rainfall data. The average weekly rain gauge data were also compared with weekly gauge-adjusted NEXRAD data for the same four-year period.