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18 which when compared with total-flow recessions disclose a pattern of level- ing off of the total recession at a relatively uniform time after a flood peak. (2) Prior studies have shown that the duration of direct surface runoff is a function of the time of concentration of rain to peak discharge for each basin. Even though direct runoff also includes some interflow, the assump- tion that direct runoff is related to this time period between a storm and its subsequent peak is sufficiently accurate. These studies developed an empirical and somewhat arbitrary relation between (1) the time from the rainfall to time of peak and (2) the time from the peak to the cessation of direct runoff. This relation gives consistent and acceptable computations of base flow. The combination of these two considerations for the Neosho River at Strawn, Kans. indicated that the direct runoff ended 8 days after the peak. This point is designated as the beginning of the base-flow reces- sion and has been applied to the recession curves in figure 5. The direct runoff from the peak of June 4, for example, was considered to have ended on June l2, and the base-flow recession consequently started at this time. The next step in the separation of base flow is to make a smooth con- nection between the end of one base-flow recession curve and the beginning of the next. This is relatively easy where the peaks are separate and dis- tinct such as the peak of July 23 in figure 5. However for the period of March, April, May and early June, the peaks are superimposed upon each other with the beginning of one recession occurring before the end of the prior recession. Under these conditions a logical assumption is that ac- cretion to base flow has occurred between peaks, and the connection should be made from the preceding recession at the time of the peak toward the beginning of the next recession for as long as direct runoff lasts. The con- nection then declines at the normal recession rate during the rising por- tion of the second peak, and then, again rises after the peak. The connec- tion constructed in this manner, describes lowering base flow during ris- ing stage and increasing base flow during falling stage. Figure 6 shows these smoothed connections for the recessions defined in figures 4 and 5. The dashed line of figure 6 has been called the base-flow hydro graph by some investigators. However, examination of this dashed line just fol- lowing the larger rises shows a very sharp rise and fall in the base flow. This response appears to be greater than the ability of the soil to transmit water in the form of ground water and interflow. These sharp base-flow peakS could have been caused by inclusion of some bank storage with the base flow. Because of this, the sharp peaks in base flow have been smooth- ed as shown in figure 7. The dashed line of figure 7 is the base-flow hydro- graph developed herein for Neosho River at Strawn, Kans. and used to com- pute the monthly mean base flow. This hydrograph is typical for Kansas.