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SECTION 2 Study Area Characteristics <br />Table 2 -1 characterizes a typical storm event for the Eugene area based on the historic 48 -year <br />precipitation record measured at the Eugene Airport: <br />Table 2 -1 <br />Average Storm Event <br />Storm Event Parameter <br />Average <br />Volume <br />0.67 inches <br />Duration <br />16.9 hours <br />Intensity <br />0.042 inches per hour <br />Since 1992, rainfall information has been recorded at six rain -gage stations within the Eugene <br />city limits. Comparison of that data with the National Weather Service's Eugene Airport data <br />indicates a significant difference between the two, with the airport data approximately 30 percent <br />higher. For additional information regarding this issue, see Section 3.1.2 and Appendix A of <br />Volume I. <br />Historically, performance of the City's drainage system has been very good. For example, the <br />City's system handled the February 1996 storm event with very few problems even though this <br />event caused widespread flooding in the Willamette River Valley. <br />2.3 Land Use and Surface Cover <br />The conversion from undisturbed to developed land uses can significantly affect the quantity and <br />quality of stormwater runoff. Runoff volumes and velocities increase as impervious surface <br />areas increase. Likewise, stormwater quality decreases due to nonpoint source pollution from <br />roadways and urban land uses such as commercial, industrial, and residential. The purpose of <br />this section is to describe existing land use and impervious surface conditions within the basin <br />and to forecast changes in these conditions due to buildout of remaining vacant lands within the <br />UGB according to Metro Plan designations. Existing land use data presented in Map 1 are based <br />upon the current use of the property as depicted on the Land Use Parcel Data GIS layer as of <br />January 2007. Buildout data presented in Map 2 are based on Metro Plan designations. It was <br />assumed that 15% of the area designated as "vacant" on the 2007 Land Use Parcel Data GIS <br />layer would be for the creation of new streets. See maps at the end of Section 2. <br />2.3.1 Existing Land Use <br />As shown in Table 2 -2, the predominant land uses in the basin are: agriculture (2,949 acres); <br />low- medium density residential (2,658 acres); industrial /airport (1,447 acres); other undeveloped <br />land (1,326 acres); street rights -of -way (1,197 acres); commercial (3 50 acres); and <br />schools /churches /cemeteries (187 acres). <br />0: 25695978 Eugene RR -SC Final Basin P1an\Master P1anTINAL 2- 2010\Master_Plan 3- 11- 10_FINAL_ Word _Version.doc 11 -8 <br />