Natural Floodplain Functions

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Floodplains naturally serve many purposes. Floodplains are areas next to creeks, rivers, and ponds that are naturally flooded from time to time. They are hydrologically important, environmentally sensitive, and ecologically productive.

  • As Flood and Erosion Control, floodplains hold water and reduce the speed of moving water, decrease peak flows, and keep sedimentation levels of our waterways down.
  • As Water Quality Maintenance, floodplains act as a filter for runoff and organic wastes.
  • As Groundwater Recharge, a floodplain will reduce the frequency and duration of low surface flows.
  • Biologically. a floodplain will hold nutrient-rich sediments from floodwaters, which build diverse ecosystems below and above ground for many species.

Do your part to keep our management systems ready to handle stormwater:

  • Drain sump pumps into lawns, not storm sewers and streets
  • Direct downspouts into vegetated areas
  • Mow with the bag to prevent grass clippings from running into the storm sewer and street
  • Manage pet waste to keep our waterways unpolluted
  • Keep litter and chemicals out of storm drains and storm sewers
  • Take care of our floodplains. Trees and shrubs stabilize the streambanks so soil won't be washed away. Don't disturb the banks by placing fill, dumping trash, or removing gravel and vegetation.
  • Read Protecting Floodplain Resources.

The Walnut Creek Watershed Master Plan was approved by City Council on Sept. 8, 2016. The plan outlines six approaches to address stormwater management and soil health within the watershed including multi-purpose projects to sustain and manage natural resources and functions like the many types of soils, streamflows, and stream characteristics. Urban Top Tier Recommendations are:

  • Use criteria listed in the Iowa Stormwater Management Manual
  • Buffer streams
  • Enforce Stormwater Pollution Prevention Plans
  • Enact local ordinances to restore healthy soils, such as the Post-Construction Stormwater Management Policy
  • Protect 100-year flood plain through
    • No structures in developing areas
    • Maintain flood storage capacity
    • Reserve open space where flooding or stream movement is expected
    • Set new structures 3' above the 100-year flood plain high water elevations

The Clive Greenbelt Master Plan was adopted on October 27, 2016. It includes responsible and attractive plans to allow smart interaction between trail users and the natural floodplain functions such as

  • Restoration of habitat health
  • Limiting flood plain development
  • Increasing stormwater infiltration
  • Slowing water flow, especially upstream

For more information, download and read the following source materials

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