Flood Forecasting Using Local Resources

A dynamic wave flood routing computer program has been used to develop a flood forecasting model for a 5000 mi**2 watershed in lower Michigan. The modeled area covers over 200 miles of the Grand River. The dynamic wave solution for the flood routing equations is used to more accurately represent the hydrodynamics of the basin which is characterized by flat channel slopes and numerous control sections. The model can forecast at virtually any point along the river rather than the limited number of locations given by the model currently used by the National Weather Service. Runoff hydrographs needed as input at the upstream boundaries of the model are obtained from the NWSRFC via their DATACOL system. Flow conditions are monitored during the flood through contact with the dam operators and calling eight stream flow gages equipped with Telemarks. Unit hydrographs are developed for 26 subbasins to represent local runoff.