ABSTRACT
This chapter discusses hydrologic simulation models and then Geographical Information Systems. Computer modeling has become indispensable for understanding the behavior of hydrologic systems, while Geographical Information Systems are revolutionizing the storage, retrieval and analysis of spatial data. GIS-assisted model parameterization is the most common use and new parameterization techniques. The two types of GIS -vector and raster and each type has certain advantages and disadvantages. This chapter focuses exclusively on deterministic simulation models. Two hydrologic models HEC-1 and AGNPS are described in detail. In the chapter's discussion surface water models are used as examples but the same procedures apply to any model. The Rainfall-Runoff part of the model is considered for HEC-1 example. The use of computer simulation models has become routine and even mandatory in many hydrologic studies. The quality of the simulation depends on the model, the input data, and how well the model is calibrated.
