What mistake did Eads and Humphreys make in regard to the levies?

Chapter Twelve discusses the 1922 rising of the Mississippi River, but it is the Mississippi River Commission that makes the mistake. Based on a misunderstood bastardization of Eads and Humphreys' analyses, the Mississippi River Commission has established a policy of levees only, on the mistaken belief that the levees will direct the river's current in such a way as to deepen the river's channel. For decades, levees have been constructed which eliminate river reservoirs and outlets. This creates new farmland but also restricts the river and increases its flow. The flow, however, is insufficient to scour the riverbed and deepen the channel.