Current methods of the HEC-1 Flood Hydrograph Package are presented. The HEC-1 model provides a wide range of hydrologic capabilities along with several unique analysis features. The current limitations of the model are reviewed. Presently, much work is being done to overcome several of these limitations. Near-term developments have concentrated on making the operational environment user friendly and improving several of the hydrologic analysis features. The direction of HEC's future watershed modeling efforts is described. These efforts focus on improving the user environment and advancing the hydrologic analysis capabilities to maintain state-of-the-art technology. Keywords: Hydrology; Forecasting; computerized simulation.

Why Arc hydro? / David Maidment / - Arc Hydro framwork / David Maidment, Scott Morehouse / - Hydro networks / Francisco Olivera, David Maidment / - Drainage systems / Francisco Olivera, Jordan Furnans / River channels / Nawajish Noma, James Nelson / Hydrography / Kim Davis, Jordan Furnans / - Time series / Damid Maidment, Venkatesh Merwade / - Hydrologic modeling / Steve Grise, David Arctur.