Real-Time Water Budgets in South Florida

One of five water management districts in Florida, the South Florida Water Management District (SFWMD) is responsible for regional flood control, water supply and water quality protection as well as ecosystem restoration in the Southern portion of Florida. Operationally, this responsibility translates to real-time control of 168 water control systems (WCSs). Analogous to watersheds in most respects, the water control systems differ in that they have control structures to regulate flow between the systems and out of SFWMD boundaries. Efficient control of these structures ensures that the multiple objectives of flood control, navigability, water supply, and ecological health are met. As part of its efforts to meet its objectives, SFWMD is building an operational decision support system (ODSS) for control of its water-control systems. The hydrological foundation of the ODSS is a water-budget-based real-time assessment of system state, which is calculated by the WCS Tracker application. The WCS Tracker is an extension to ESRI's ArcMap software and receives as input: time series of gage and radar-based rainfall, gage-based evapotranspiration, and flow and stage measurement of the control structures. This paper will describe improvements in WCS Tracker calculation methodologies for real-time water balance modeling, upgrades to algorithm performance, and improvements in user interface design. Specifically, (1) a "drying" model is introduced to estimate actual evapotranspiration (ET) from measured potential ET and catchment characteristics; (2) rainfall estimation based on NEXRAD data is shown to be superior to previous gage-based values; (3) calibration of catchment parameters via novel procedures employing non-parametric ranking of climatic state is introduced; and (4) a WCS aggregation-disaggregation technique is shown useful for estimating term-wise bias.