DIGITAL HYDROLOGIC MODELING METHODS FOR WATER RESOURCES ENGINEERING WITH APPLICATION TO THE BROAD BROOK WATERSHED (CONNECTICUT)

Methods are presented for the digital simulation of the hydrology of a small rural watershed. Development of the methods has been accomplished using the Broad Brook Watershed in northcentral Connecticut as a prototype watershed although the methods reported may be generalized and applied to other small watersheds. A computer model called the Small Watershed Hydrologic Analysis Model (SWHAM) is constructed by linkage of an existing one-dimensional Ground Hydrology Model (GHM) to an existing channel flow model through a newly created overland flow model. Methods for the creation of a digital database of watershed data including soils, land-use and land cover, and topography are presented using the MAP geographic information system (GIS), and the created database is then coupled with SWHAM. Meteorological data collected from several sources are used to drive SWHAM. Model output consists of the soil moistures, vegetation and soil temperatures, latent and sensible heat fluxes, and the basin discharge hydrograph. A sensitivity experiment is conducted using SWHAM to demonstrate the usefulness of the model in water resources engineering by assessing spatial variations in hydrologic inputs.