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8 I I / The 50-year rainfall distribution is only slightly indicative of the distri- bution of expected flood magnitudes. Figure 3 shows that the extreme mag- nitudes of the 50-year rainfall vary by a ratio of less than 2 to 1 in Kansas. But the regional flood-frequency analyses in subsequent sections of this report indicate that the magnitude of the 50-year flood may varyby a ratio of as much as 10 to 1 for areas of equal size located in opposite ends of the State. The foregoing emphasizes the futility of applying rainfall to ~pirical floodjgr- mulas withouLa_pr:oper_evaluation and consideration of the numerous other ractors that affect runoff. RECORDS AVAILABLE The base data for this report were largely derived from streamflow re- cords collected in Kansas and adjoining areas by the Geological Survey and other agencies. Table 1 contains a list of 138 gaging stations for which flood- frequency relations have been defined. The list includes all stations in Kansas where records of five or more years of defined peak discharge have been ob- tained. The stations in table 1 are listed in consecutive downstream order in agreement with the order used since 1951 in publications of the Geological Survey. The gaging stations are identified by numbers in the left column of table 1 if operated by the Kansas district or by letters if operated by districts of adjoining States, The identification symbols for the gaging stations are the same as thos e us ed in each of the other Technical Reports in this series. Lo- cation of the sites is identified in figure 4. Total and contributing drainage areas for each station are given in table 1. These areas are identical for many stations, but in some sections of the State, particularly the western part, surface runoff is retained on the flat table lands or is collected in depressions or closed basins so that it seldom reaches a major stream as direct surface contribution. Undoubtedly some of the collected water percolates into the ground and eventually enters a stream as groundwater effluent but it has an insignificant influence on flood discharge. These areas have been deducted from the total and the result is the area contributing directly to surface runoff. The contributing drainage area has been used as a correla- tive parameter in this report, There is a possibility that contributing area may increase with size of flood peak; uncertainties in this regard may be a minor source of correlative error. Mean flow, in cubic feet per second per square mile (ds per sq mi), ad- justed to the period 1921-56, is shown for each station as indicated.