Given the complex nature of hydrologic process in South Florida and the flood protection works that affect the hydrologic cycle, it is essential to have hydroinformatic systems to assist decision makers. The hydroinformatic systems must contain hydrologic models that can accurately simulate physical processes at the proper time and space scales without the crude schematization that has been common in previous modeling systems. The developed hydroinformatic system includes the FEMWATER123 model supported in the Department of Defense Groundwater Modeling System (GMS). The developed model (FEMWATER123) uses the Galerkin finite element method to simulate 1-D canal flow, 2-D overland flow, and 3-D groundwater flow in a coupled manner. The canals are simulated using the 1-D diffusive wave assumption including hydraulic structures with individual operation rules that are updated at one-minute intervals. The overland areas are simulated using the 2-D diffusive wave assumption while variably saturated groundwater flows are calculated using Richards equation. Results from the South Florida application are presented. Copyright ASCE 2004.