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I V-2 Special Usage of Program. Since thi. pro~ram has been found to be more suitable for use in analyzing large rivers rather than intermittent, steeply sloped gulches, some special consideration y,la~, necessary for usaqe on Lena Gulch. This was done by specifying extra cross sections near culverts so that the sudden transitions and expansions in channel cross- sectional areas could be adequately handl ed. The 11l0-year future discharges were routed and the ",ater surface pro- file determined. Using this information, the flood plain was plotted on the 1 inch to 100 foot scale mapping. The program output then gives more than enough flow information to estimate within a few inches the flow profiles for other frequencies. FLOOD DAMAGES The floodplains and depths plotted on the 1 inch to 100 foot scale map- ping revealed the extent of flooding by incremental reaches of the gulch. The extent of flooding was related to general first floor levels of structures. Damages were then tabulated according to type of structure and similarity of levels of flooding for each reach. USACE damages curves were then used to calculate percentages of struc- tural and contents damages for the various levels of flooding. The USACE curves do provide estimates of flood damage for water levels which are lower than the first floor elevation, In this vial', damage due to excessively high water tables is also included. The actual valuation of structures and contents determined for each reach was based upon insurance company estimates, estimates by local governmental entities, various real estate evaluations and general ex- perience in the Denver region by our office. Table IV-l presents some of the typical average values that were appl led. (Note that in specific instances other values were used). This provided a basis for estimating the dollar value for the 10, 25, and 100-year flood events.