In the my last blog post about flooding we talked about how floods impact our communities and can cause lots of harm and destruction. In this post we’re going to explore what floods really are. I know what you might be thinking– didn’t we already talk about this? In my first blog post we dived into what a 100-year flood is and some of the conditions that contribute to flooding. Today though I’m going to talk about flooding beyond their impact on humans and how to understand flooding as a natural phenomenon.
Many may be familiar with the old saying, “If a tree falls in a forest and nobody is around to hear it, does it make a sound?” This age old question raises many questions about our world, the role human perception, and natural disasters. If a river floods and no human lives are disrupted, is it really a disaster?
Freshwater scientist Jeff Opperman explains this in an interview with The Nature Conservancy about basic flood science:
“But what most people don’t realize is that floods are not some departure from the way a river is “supposed” to behave – witness the common description in the press of a river “bursting from its banks” during a flood, like a convict breaking out of jail. The river and floodplain are actually one single highway for moving water downstream (and not just water, but also sediment, which is why the Missouri River is nicknamed the “Big Muddy.”) It’s just that the floodplain part of this highway is dry much or most of the time.
Think of the river-floodplain system as all the highway lanes at a bridge toll crossing. For much of the day and night only a few booths are open and only a few lanes needed. But for the occasional “rush” hours, the flood of cars can only be contained by using all the booths and filling all the lanes. The cars are not “bursting out of their street” – they simply use all of the lanes only during the moments of intense traffic flow.”
When river levels rise and spill onto the floodplain, the river deposits rich sediment. After many years of these sediment deposits building up, extremely fertile soil results. Ecosystems depend on these natural patterns of flooding as well- trees and other vegetation in the floodplain forest have adapted to thrive in these conditions. By keeping all floodplain areas completely dry we restrict the full benefits of river systems.
If you live near a river or stream you can see and protect your local floodplains. Contact your local Mississippi River Network (MRN) members and ask if they have any floodplain restoration efforts that need volunteers! Your local organizations are likely involved in shoreline stabilization, rain garden creation, prairie restoration, or other activities that help mitigate the ill effects of flooding.
1 Mississippi Minnesota Outreach Assistant