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e f which results are shown is the Trail Creek watershed which occupies about I:! sq. miles of the pilot study area of 300 sq. mites and includes a portion of the city of Athens. Georgia. The test area is presently about 10 percent urban and expected to grow to 20 to 30 percent urban by 1990. The data bank created for Trail Creek Included the 15 data variables shown in Figure I at a grid size of approximately 1.1 acres (Hydrologic Engineer- ing Center. Trail Creek, 1975). '" e HEC-SAM The HEC-SAM system, assembled to perform these studies, is comprised of a family of data management and analysis computer programs that service the full range of com. prehensive assessments. Figure 1 presents a functional flow diagram of the analysis process and input and output results. About 1/3 of the links shown on the diagram for the Interface and Analysis programs are presently automated and these links are intended to be highly automated in the near future. The system has three distinct functional elements: Data Bank Management, Data Bank Processing Interface, and Comprehensive Analysis. The data bank management element is comprised of the subfamily of computer programs required to process raw map or other type data into the grid cell format that becomes the general data bank. This includes a program that permits displaying data digitized in the grid <;ell format (GRID, Harvard, 1971), a program that displays data digitized in the polygon format and generates grid cell data from polygon format data (AUTOMAP II, Environmental Systems Research In- stitute), special-purpose programs to create grid topographic data from digitized contour lines (Tapa, LINES), and programs to properly register poly gun data to the base grid coordinates (REGISTER) and place the grid data into the general data bank (BANK). The Data Bank Processing Interface element is comprised of the subfamily of com- puter programs that compile and reformat geographic and resource data retrieved from the data bank into a form processable by the general analysis computer programs. The programs service the functional analysis areas of flood hazard, flood damage and environ- mental status. HYDPAR links the data bank to the flood hazard analysis by retrieving the data variables of hydrologic subbasins, slope, soil group and land use to generate the modeling parameters required to simulate storm runoff. HYDPAR also provides links to the environmental analysis by retrieving land use. soil and subbasin data from the data bank and generating modeling parameters required to simulate the quality of urban storm runoff and land surface erosion. The link between the data bank through HYDPAR to the analysis program STORM is completely automated. DAMCAL links the data bank to the flood damage analysis by retrieving the data variables of damage reach, land use, topography and reference flood to generate elevation-damage tables by land use category and damage index location for subsequent integrated analysis. A TODT A also serves the flood damage analysis by restructuring the DAMCAL generated data, interfacing it with hydraulic and hydrologic probability data and providing an automated liok to the general hydrologic and damage analysis program HEC-I. The linkage from the data bank through DAMCAL and ATODTA to the analysis program is completely automated. The Comprehensive Analysis element is comprised of the general simulation and analy- sis computer programs that perform the detailed technical assessments that compare the existing condition to the development condition of interest. In most instances the final analysis computer programs are standard Corps of Engineers analytical tools that have . f e 3 L