The Effect of Agricultural Drainage Upon Flood Run-Off

A survey of completed drainage enterprises in the Upper Mississippi Valley indicated that a comparison of stream-flow conditions prior and subsequent to extensive drainage could best be made upon the Des Moines and Iowa Rivers, a large portion of the water-sheds of which have been covered with artificial drains subsequent to the establishment of stream-gauging stations. A critical examination of the records of these two streams shows that during flood periods there has been no significant change in their behavior which may be attributed to drainage. The total run-off from storm s of like precipitation, the maximum rates of discharge, and the rain-water storage conditions within the basins seem to have been unaltered by the extensive drainage operations. It is believed that if any of these factors had been changed by a measurable a mount, such fact could easily have been detected by the analysis made in this paper.