Taking the flood pulse As researchers learn more about rivers and their cycles, they are developing new concepts to understand them. One is the flood-pulse concept. During a flood, a lot of this material and the nutrients from it come into the river. Also, the invertebrate production in the flood plain is huge. These invertebrates are key to the river, and to the fish that eat them.
Rivers are very competitive systems.
When flows are low, a lot of predators eat the young fish. But during a flood, the young fish get spread out, so you've got this added volume of water that protects young fish in addition to giving them a tremendous new food supply. Aadland notes that flooding also shapes the river valley. Frequent spring floods reconfigure the channel itself, but bigger events contribute to shaping the entire flood plain. But all that's really happening there is that the river is reclaiming its flood plain.