The Importance of Floodplains

Floodplain

Floodplains are the low-lying areas adjacent to rivers that are formed by sediment deposited by rivers and subject to flooding. The floodplain is an integral part of a river and is essential for a healthy functioning river system. Floodplains provide a variety of benefits for people, fish and wildlife.

  • Fish & Wildlife Habitat – Floodplains provide biologically diverse and productive habitats for fish, plants, and countless forms of wild species. They provide vital resting and feeding grounds for migratory birds, critical spawning and rearing areas for fish, and food for a diverse array of wildlife. 
  • Clean Water – Rivers carry an array of pollutants like sediment and chemicals, particularly after storms. Floodplains provide space for flood waters to spread and slow, thereby allowing pollutant laden water to filter through the soil. This keeps river water cleaner for fish and wildlife, for drinking water, and for recreation. Trees in floodplains can also help keep water cooler through shading.
  • Flood Protection – When connected to rivers, floodplains can provide flood protection by holding water that has overflown a river’s banks during and after storms. Floodplains can hold great quantities of flood waters, preventing floods from damaging nearby communities. They are a natural and effective line of defense. The United States spends billions of dollars each year on flood and crop insurance, flood control structures, flood fighting, and flood damage clean-ups.  Protecting floodplains and natural flood storage would significantly reduce these costs.
  • Ground Water Recharge – Groundwater is the water found underground in the cracks and spaces between soil and rock. It is stored in geologic formations called aquifers. We depend on groundwater for much of our drinking water and for irrigation. Groundwater is also an important source of water for rivers, lakes and wetlands during drier periods. Floodplains allow flood waters to percolate through the soil and replenish aquifers.
  • girl splashing in canoeRecreation – Floodplains provide a rich array of recreational opportunities like fishing, paddling, hiking and wildlife viewing.
  • Fertile Soil for Farming – Thanks to rivers, floodplains contain rich, fertile soils making them productive areas for growing crops. Sustainable agriculture practices, such as the production of flood tolerant biofuel crops can be highly compatible with healthy floodplains.

The Problem: Disconnected Rivers

features of a floodplainDespite the many benefits of floodplains, rivers across the United States have been disconnected from their floodplains on a grand scale, largely through river channelization and levees. A levee is typically an earthen wall built along a river to keep high flows within the river and away from the land and structures behind the levee. The levee severs the connection between river and floodplain.  The Mississippi River alone has more than 2200 miles of identified levees, with many more that are unmapped and unidentified.

Stream channelization in smaller rivers also leads to river floodplain disconnection because water flows more quickly in channelized streams, leading to downward erosion and incision that leaves the stream bed so deep it can no longer overtop its banks and reach the floodplain area.

Once a river becomes disconnected from its floodplain, the benefits noted above cannot be realized. In addition, levees can and often do fail, and when they do lives, homes and businesses suffer.

Levees (and other engineered structures) also make floods worse because they force flood waters into a narrower river channel, making the water flow higher, faster and with greater force, which can cause more powerful floods both up and downstream.

The Solution: Reconnecting Rivers & Floodplains

Floodplains are an essential part of both healthy river systems and healthy communities. A growing number of flood managers, scientists, conservation groups and communities are recognizing the importance of river-floodplain reconnection. One effective method for achieving reconnection is through levee setbacks or removals. Setting a levee further back from a river can allow for greater floodplain connection while still protecting buildings or crops behind the relocated levee. In some situations, total removal of the levee may be warranted, or what’s known as notching or openings in the existing levee that allow floodwaters to reach the floodplain.  Levees have been altered to allow greater river floodplain connection on the Missouri, Maquoketa and Iowa rivers in Iowa, and on many other rivers in the west.

Importance of Protecting Wetlands

Wetlands

A wetland is a land area that is covered with water, either permanently or seasonally. The primary thing that distinguishes wetlands from other land forms or water bodies is the presence of aquatic plants specifically adapted to the hydric, or very wet, soils found there.

Wetlands are considered the most biologically diverse of all ecosystems. As such they provide habitat for thousands of plant and animal species. Migrating birds use wetlands to rest and feed and as nesting sites. Wetlands provide other important benefits, such as filtering water pollutants, storing flood waters, recharging ground water supplies, and providing recreational spaces.

The Problem: Wetland Destruction

For too long, wetlands were viewed as wastelands to be filled in and built upon. As a result, extensive losses have occurred and more than half of the country’s original wetlands have been drained and converted to other uses. By the 1980s, Illinois had lost 85% of its wetlands.

Wetland destruction has serious consequences like increased flooding and species extinction.

The Solution: Restore and Protect Wetlands

Prairie Rivers Network and a coalition of partners is fighting one particularly destructive project called the St Johns New Madrid Floodway project. The project includes building a new levee that would cut off a very critical area of wetlands on the Middle Mississippi River from the river’s water, thereby destroying more than 50,000 acres of wetlands. Learn more about the campaign to #stopthelevee.

 

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