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<br /> <br />96" <br /> <br />2.55 <br /> <br />44" <br /> <br />2.75 <br /> <br />.s:~ <br />'5 0 <br />o 1a 430 <br />000 <br /> <br />., <br /> <br />4'" <br /> <br />\ Base lrom U.S. Geotogk:al Survey digital data, <br />\ 1 :2,000,000, 1979 <br />Universal TliInsv&rSe Mercalor pl'O/edlon, <br />Zone 15 <br /> <br />93" <br /> <br />t <br />~ <br />~ <br />'to <br />., <br /> <br />! <br />." <br />~ <br /> <br />20 40 <br />, " ' <br />20 40 <br /> <br />EXPLANATION <br /> <br />~ AREA OF EQUAL 2-YEAR, 24-HOUR PRECIPITATION <br />INTENSITY --Number is precip~ation intens~y, in incbes <br /> <br />Figure 5. Distribution of 2-year, 24-hour precipitation intensity for Iowa and southern Minnesota. <br /> <br />reference and the cartographic data source used <br />for both GIS procedure and manual <br />measurements. <br /> <br />Verification of Drainage-Basin <br />Characteristics <br /> <br />I <br /> <br />~ <br /> <br />To verify that the drainage-basin <br />characteristics quantified using the GIS <br />procedure are valid, manual topographic-map <br />measurements of selected drainage-basin <br />characteristics were made for 12 of the <br /> <br />streamflow-gaging stations used in the <br />drainage-basin flood-estimation method. These <br />comparison measurements were made for those <br />primary drainage-basin characteristics <br />identified as being significantly related to flood <br />runoff in the multiple-regression equations <br />presented in the following section entitled <br />"Drainage-Basin Characteristic Equations." <br />Comparison measurements were made from <br />topographic maps of the same scales as were <br />used in the GIS procedure. The results of the <br />comparisons are shown in table 1. <br /> <br />ESTIMATING DESIGN-FLOOD DISCHARGES USING DRAINAGE-BASIN CHARACTERISTICS 13 <br />