IMPROVING UPON A GIS-BASED SPATIALLY DISTRIBUTED RAINFALL-RUNOFF MODEL

by Emerick, James F

IMPROVING UPON A GIS-BASED SPATIALLY DISTRIBUTED RAINFALL-RUNOFF MODEL James Emerick, M.S. University of Pittsburgh, 2003 The modeling of small dendritic watersheds has always been a difficult undertaking. The lack of streamflow data and reliable rainfall data, and the inability to model distributed properties have all been reasons for this difficulty. With improvements in computer technology, advancements in radar rainfall measurement, and the innovations in Geographical Information Systems (GIS), it is possible to make improvements to existing modeling techniques. This, along with increasing environmental concerns, has sparked new interests in the development of watershed models. This goal of this research has been to improve upon a Geographical Information System based rainfall-runoff model. A major improvement to the model has been the implementation of spatially distributed incremental rainfall data obtained from gage adjusted radar measurements. The significance of the radar data is the representation of highly defined spatial and temporal distribution in the rainfall measurements. The current model also makes use of distributed properties of the watershed such as elevations, slopes, soil types, land cover, and stream networks. The direct runoff is calculated using a distributed Curve Number Method. The hydrograph is then developed by the use of a distributed map of isochrones. The model was tested for a small watershed where streamflow data was available. The goal is to test and calibrate the model so that it can be used in watersheds where there is no streamflow data available. DESCRIPTORS Curve Number DEM Distributed GIS Hydrograph IDRISI Runoff SCS Watershed