Coastal, inland, and island environments are simulated using a fully distributed physicsbased approach that relies on geospatial data to set up the model. Calibration and evaluation of the model offers insight into climatic controls affecting soil moisture, and operational forecasting of basins in different climatic regimes. Long-term model performance is found to be consistent between the event scale and long-term inter-annual periods when calibrated to represent large events and interim periods dominated by low flow. Physically realistic parameters result from the calibration method applied to parameters derived from geospatial data. The amount of surface runoff is simulated by numerical solution of conservation equations, parameterization from geospatial data, and inputs defined by radar and rain gauge.

Advances in physics-based distributed hydrologic modeling makes it possible to support real-time decision making for reservoir operations; hydrologic analysis of storm events; long-term water balance runoff-recharge studies; and prediction of site-specific flooding for stormwater and emergency management. Evaluation of the model in a variety of hydrologic climatic regions and applications demonstrate capability for flood forecasting, long-term simulations, and in event-based modeling of land cover/use effects. Vflo results are presented for a coastal watershed near Houston Texas, an inland watershed in central Oklahoma, and an island watershed on Puerto Rico near San Juan. Conclusions and lessons learned include the sensitivity of various model parameters and climatic controls affecting calibration and distributed hydrologic prediction and analysis.