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flood hydrographs using the CUHP methodology or the SCS methodology is very computationally intensive making it practical to use these methodologies only with the aid of a computer. The SCS computer model for watershed analysis using the SCS unit hydroqralph methodology is know as TR-20. The TR-20 model also includes various method,; of channel routin<;r and can bEa used. to rout and combine hydrographs from diffE,rent: s:ubcatchments with the watershed being studied. The HEC-1 Hydrologic Model by the U.s. Army Corps of Engineers now includes the SC:, Hydrograph Methodology as OnE! of t.he available methodologies (Ref. 12). The TR-20 computer model is available from the National Technical Information Service and the HEC-l Hydrologic Model is available from the U. S. Army Corps of Engineers" 'rhe computer software for computation of'flood hydrographs using the Colorado Urban Hydrograph Procedure (CUHPE-PC) is available from the Urban Drainage and Flood Control District in Denver. The use of the methodologies include,d in the Storm WatE!r Managemen1t Model (SWMM) has gained wide acceptance in Denver as the preferred methodlogy for routing combining hydrographs from sub- catchments developed usinq the CUHP methodology. The computer software that ha,; been adopted for this pur- pose (UDSWM2-PC) is also available from the Urban Drainag'e and Flood Cont.rol District. The SCS has developed a simplified method that allows for thE! development of flood peak discharges without the development of a convoluted unit: hydrograph. An example will be present,ed using this simplified method- ology. ~ Th,~ Rat ional Formula m,~th()dology probably falls wi thin the category of the Design Storm Approach to flood hydrolcgy. The Rational Formula met;hodology is sim- 11