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<br />CHAPTER III <br />HYDROLOGIC ANALYSIS <br /> <br />A. General <br />The purpose of a hydrologic analysis in a major drainageway planning study <br />is to define the storm runoff peaks and volumes such that an assessment of <br />drainage conditions, flood plains and potential drainage facilities improvement <br />can be made. The resulting flood plain defines the average annual damage <br />potential, which is an indicator of the degree and amount of improvement <br />protection needed. From these results, a logical method of choosing improvement <br />alternatives can be obtained. The purpose of this chapter is to define the <br />methodology and results of the storm runoff analysis. <br />B. Study Area Breakdown <br />The basin boundaries, as previously defined in the Project Reuse Report 4 , <br />were used in the contract for preliminary basin delineation. A detailed investi- <br />gation of the flow patterns of the area, using Arvada City maps, Adams County <br />maps, State Highway plans, large development drainage plans and several field <br />investigations, showed that the original basin boundary had been significantly <br />changed by man. The original basin definition extended to just west of Wadsworth <br />Boulevard. The present basin extends to west of Carr Street (an additional net <br />area of 95 acres). The boundary shifts to the north and south near Sheridan <br />Boulevard also increased the basin area by approximately 160 acres. Approxi- <br />mately 117 acres were added to the extreme northeast portion of the basin near <br />Little Dry Creek. Several smaller areas of the basin were actually removed from <br />the original boundary, the largest being about 34 acres. A table showing the <br />basin area changes is presented on the following page: <br />