Storm‐discharge of streams in the upper Mississippi Valley consists of surface‐flow and storm‐seepage. The total runoff, resulting from a storm, of either of these components does not bear a fixed relation to the runoff of the other. The two are influenced by different sets of conditions.
The two components of the storm‐flow can be separated by graphical analysis. A reversal of the process has been found useful in determining the hydrograph of ground‐water flow.