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<br />Table 3.--Results of station-year method <br /> <br />Range in size of <br />effective <br />drainage area, <br />AE, in square <br />miles <br /> <br />0.50 to 2.99 <br />(average AE=1.74) <br /> <br />3.00 to 7,00 <br />(average AE=5.00) <br /> <br />7.01 to 15,0 <br />(average AE=11.0) <br /> <br />Flood <br />charac- <br />teristic <br /> <br />Station-year <br />result, in <br />cubic feet <br />per square <br />mile <br /> <br />Q10 <br />Q25 <br />Q50 <br />lQ100 <br /> <br />316 <br />588 <br />872 <br />1,240 <br /> <br />211 <br />464 <br />765 <br />1,196 <br /> <br />170 <br />328 <br />499 <br />724 <br /> <br />Q10 <br />Q25 <br />Q50 <br />lQ100 <br /> <br />Q10 <br />Q25 <br />Q50 <br />lQ100 <br /> <br />lResults shown in figure 6. <br /> <br />Peak discharge, in cubic <br />feet per second <br /> <br />For range <br />in AE <br /> <br />158- 945 <br />294- 1,758 <br />436- 2,607 <br />620- 3,708 <br /> <br />633- 1,477 <br />1,392- 3,248 <br />2,295- 5,355 <br />3,588- 8,372 <br /> <br />1,192- 2,550 <br />2,299- 4,920 <br />3,498- 7,485 <br />5,075-10,860 <br /> <br />For average <br />AE <br /> <br />550 <br />1,020 <br />1,520 <br />2,160 <br /> <br />1,060 <br />2,320 <br />3,820 <br />5,980 <br /> <br />1,870 <br />3,610 <br />5,490 <br />7,960 <br /> <br />TECHNIQUES FOR ESTIMATING THE CHARACTERISTICS OF <br />FLOOD FLOWS FOR SMALL WATERSHEDS <br /> <br />The purpose of the analysi s of flood data collected on small watersheds in <br />the Arkansas River basin during the lO-year study period was to provide improv- <br />ed estimates of the magnitude and frequency of flood flows, and the volumes <br />associated with these floods. Based on this preliminary analysis, the following <br />sections bri efly di scuss the best methods of estimating these flood characteri stics <br />for small ungaged rural watersheds. To aid users in application of these results, <br />table 4 summari zes the necessary equations. <br /> <br />Magnitude and Frequency of Peak Discharges <br /> <br />Peak discharges were studied using (1) a multiple regression method applied <br />to flood-frequency estimates which were based on recorded data from the study <br />basins and synthetic data from a calibrated rainfall-runoff model, and (2) a <br />station-year method applied only to recorded station data. The results of this <br />study indicate that equations 12 to 19, which are based on the multiple-regression <br />method, will statistically provide the best estimates of the magnitude and frequen- <br />cy of floods on small rural watersheds in the Arkansas River basin. These <br />equations are given in table 4 and are applicable to rural drainage basins ranging <br /> <br />24 <br />