HEURISTIC KNOWLEDGE-BASED TOOL FOR RAINFALL SYNTHESIS, RUNOFF ESTIMATION AND HYDROGRAPH GENERATION

Knowledge-based engineering has emerged as a potential technique for i ncorporating human expertise and some degree of intelligent judgment i nto decision-supporting procedures. A knowledge-based expert system (K BES) methodology to estimate the volume and hydrograph of direct surfa ce runoff from rain events using the Soil Conservation Service Runoff Curve Number method was developed for hydrologic modeling and decision support systems. The KBES approach was designed to determine runoff c urve numbers with limited available information on watershed character istics, to generate rainfall intensity of the geographic location for desired durations and return periods, and to use the curve number and rainfall intensity estimates to calculate runoff volume, peak runoff a nd time-to-peak for design purposes. Rainfall intensity estimation is based on four regional partial-duration series parameters correspondin g to a given geographic location. Currently, a regional parameter data base for 12 midwestern states (Illinois, Indiana, Iowa, Kansas, Michig an, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, a nd Wisconsin) is compiled into the KBES for the rainfall synthesis.