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<br />"...4o ...... '1 <br />,. <br /> <br />11 <br /> <br />flo\',' bet\\'een adjacent basins is not so readily apparent. Such large dif- <br />ferences show that base flow cannot be I'eliably estimated fl'om this map <br />in ungaged basins or' sub-basins, and the latter pal't of this l'eport shows <br />how the consideration of other information will permit a better estimate of <br />base flow, <br /> <br />Helation of Base Flow with Total Streamflow <br /> <br />The ratios of mean base flow to mean 10tal streamfluw al'e shown fOl' <br />each hasin and sub-basin in figure 3, The I'atios are determined from the <br />values of flow in the standal'd base pel'iod, gencl'ally 1923-62 (Technical <br />repol't 6A). The scattel' of \.'alues is ~maller in figure 3 than in figure 2 <br />hecause of the inten'elatinn of the hase-flow component with total stream- <br />flow. Base flow averages 23 pet'cent of total flow at the 105 ~ub-basins, <br />but indi....idual pI'oportions range from 2 peccent to 58 pel'cent. Rase flow <br />is a lal'gel' proportion of total flow in streams of rnon~ highly sustained <br />10v... flow, as shown by compal'ing values in figul'e 3 with those for 7-day, <br />30-day and 120-day rates of minimum flow in Technical repol't 2, Also <br />base flow is a larger' prDpor'tion of total flow in stl'cams having smaller' <br />variations in total flow, which in tUl'n are those with a smaller' variability <br />index (fig. lOa, p, 128). <br /> <br />The ratio of base flow to total flow may be slightly gl'catel' in r'eccnt <br />years than the average during the base !Jet'iod because of the expansion in <br />construction of small ponds. These include about 70,000 farm ponch; and a <br />lesser numbel' of l'ec reational ponds. These ponds may release somc water <br />over thei,. spill\l/ays during unusually high floods, discha!'ge some water <br />through outlet pipes when the ponds are full, Or' lose \I/ater by seepage if <br />not tightly constructed, But, in general, these ponds stop a small but de- <br />finitive percentage of flow from their dl'ainagc basins, ,..-hieh range in size <br />genel'ally from one to sevel'al hundred act'CS, :\s j)l'actically all basins of <br />these sizes in Kansas have dry channels except during pel'iods of direct <br />['unoff. the ponds have very little effect on the hase-now POl'tilll1 of total <br />flo\\' but hold back mostly the dil'ect nmoff pOl'tion, If the quantity of di- <br />rect runoff abstl'acted annually by the small ponds may be apPl'oximated <br />by the evaporation fl'om the ponds. it may bL~ computed to equal 4 percent <br />of the total runoff genel'ated in the ~tate. The existing minor effect of <br />these small ponds on dil'ect l'unoff emphasizes one advantage of working <br />'....ith base-flow data rather than with total flow in the futlll'C because the <br />many larger detention reservail's planned for Kansas watel'sheds will l"e- <br />tain a significant part of dil"ect l"unofr. <br />