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<br /> <br />8 <br /> <br />for reliably estimating base flow at the I'emaining shorter-term stations <br />for these years. Rut with the passage of time since the eadier studies, <br />added recQ)'ds are now available at most stations for the years 1957-62. <br />Because 15 stations have complete or nearly complete J"ccords for' the years <br />1923-62, this 40-year per'Lod has been selected as the base period to which <br />base-flow recol'ds have been extended, as far as reliahly possible, for 84 <br />streamflow stations in Kansas and vicinity. The method of extension has <br />been descrihed in Technical repoI't fi...\ (p. 14:0, 14ll. The years in the base <br />period ID23-G2 are termed "wate1' years" encompassing the months Ucto- <br />ber thl'ough SeptembCI', so that the base pel'iod is from October 1. 1922 to <br />September 3D, 1962. For a number of stations located in not'thwestcrn <br />Kansas. the base pCl'iod could not be used in its entil"ety because of lack of <br />cOITelahve recol'us. <br /> <br />The avel'a~e now can be expected to change some\vhat with change in <br />base period. For example. the quantity of \vate!' ultimately pasBing out of <br />Kansas in the period 1921-56 averaged 20,700 cfs as compared with 5 per- <br />cent more dudng the per'iod 1923-62. Such a uifference raises the question <br />whelherperiods a:=; f:hol't as 36 or -10 year's ar'eadequate to represent long- <br />term avel'ages. EadieI' streamflow records ar'e too meager to resolve the <br />question. Heeol"ds of droughts and rainfall pl'ovide longer guidelines, Two <br />extensive droughts, one in the W30's and one in the l!J50's. were experi- <br />enced within the hase period 1923-(32. Flora Ofl-t8) descI"ibes earliel' <br />droughts in the 1860's, 1870rs, 1890's. lDOO's, and lOlO's and consider's the <br />drought of the 1860's to rank with that of the l!J30's, Thus. drought evenls. <br />although of indefinite magnitude. seem to have been experienced pl'oportion- <br />ally in the base period. Rainfall records have been collected at eight sitef; <br />in Kansas continuousl.... since 1878 and show that in the pel'iod 1923-62, I'ain- <br />fall avel'aged 1 pel'cent less per yea!' than in the period 1878 to 1962. The <br />foregoing expcl"iences ar'e not fully definitive, but in general they imply <br />that the period lP23-62 is a reasonably l'epl"t'~entative base pel'iod. <br />