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known a.s "rainfall excess" fro::n the design storm mass rainfall curve or from the design storm hyetograph. Th(~ CUHP procedure is basE!d on the Horton infiltration equatic>n which assumes an exponential decay in loss rate with time. The Urban Drainage and Flood Control District has again calibrated t;he infiltrat;ion parame- ters that go into the Horton infiltration model to replicate infiltration characteristics that have been found to exist in the Denver area. The SCS Methodology for calculating runoff is based on a composite runoff curve number for the watershed. The runoff curve number can be calculated as a function of soil types and land use characteristics. soil types are deter- mined from The SCS Soil Survey Reports which are avail- able for most rural counties and land use characteris- tics can be assessed from aerial photographs or by field reconnaissance of the watershed. The SCS method- ology is attractive to many people who need. to develop flood flow frequency relati,onsh:~ps for rural watersheds because the analysis of infiltration is rationally based on soil types and land use and does not require a lot; of;Jeneralized assumptions. ThE! final step in the application of the design storm methodc>logy is the calculation of the actual flood hydrogr~ph resulting fromt.he dE!sign storm runoff. The computation of the actual flocd hydrograph resulting from tte calculated runoff from the design storm is based on the linear thE:ory of hydro losric systems. The computation process itself is known as unit hydrograph convolution and is well documented in the Urban Storm Drainag'~ criteria Manual d'3veloped by Wright;-McLaughlin Enqinee::s. The mathematical computation itself can be . ~ broken down into a. matrix vector computation that can be accomplished on advance spreadsheet software such as LOTUS or QUATTRO. The development of hypothetical 10