Wednesday, December 11, 2013

Restoring Riparian Habitat for Soil & Water Conservation

By Travis Smith, Wildlife/Forestry Specialist 
I was working as a research biologist conducting biological assessments in the Great Miami River watershed when I was first exposed to the incredible impact that sediment pollution can have on an ecosystem.  I did not realize how major of a role  riparian vegetation played in soil and water conservation until I observed  firsthand the impacts of sediment pollution on an ecosystem where no riparian BMP’s (Best Management Practices) were utilized.  The entire reach of the river adjacent to the farm was completely silted in, which destroyed pool, riffle, run, structures, thus creating monotypic morphology.  It also destroyed important breeding habitat for many sensitive aquatic wildlife species, and decreases bank stabilization.  Decreased bank stabilization can cause sloughing, bank slippage, and extreme soil erosion, which results in the loss of valuable cropland.  With the demand growing for viable cropland which is needed to meet the world’s growing food supply, we can ill afford to let our farmland continue to be washed away.              

The riparian zone:  is the interface between the land and a river or stream.  Riparian zones are significant in ecology, environmental management, and civil engineering because of the role they play in soil and water conservation

Riparian zones function in the 4Rs

The 4R nutrient stewardship represents the four rights of fertilizer management- source, rate, time, and place.

The impacts of eutrophication caused by the increased use of fertilizer needed to keep up with the growing demand for crops have been felt by the presence of toxic algae blooms in numerous lakes, rivers, and streams throughout Ohio.  Currently Grand Lakes St. Mary and the Sandusky Bay are probably the two biggest hot button topics in the state related to this issue.

Research shows riparian zones are instrumental in water quality improvement for both surface runoff and water flowing into streams through subsurface or groundwater flow. Particularly the attenuation of nitrate or denitrification of the nitrates from fertilizer in this buffer zone is important. Riparian zones can play a role in lowering nitrate contamination in surface runoff from agricultural fields, which runoff would otherwise damage ecosystems and human health. This process is also called biofiltration.  

Controlling the source, rate, time, and place of fertilizers are extremely important, but could be made exponentially more effective with the restoration of the riparian buffer zones to aid in sequestering excess nutrient runoff.

Types of Restoration

Horticultural restoration- refers to a high level of site management and external human inputs that include site preparation (land-leveling, disking), planting of nursery-grown trees and shrubs in predesigned patterns, irrigation, and chemical weed-control for three or more years. Horticultural restoration is appropriate along rivers where the river’s physical processes have been severely modified by humans with dams, levees, bank stabilization, and water diversions.

Process restoration- which strives to reestablish river processes onto the site. Process restoration is appropriate on riparian sites along a river that retains functioning river processes (e.g. no dams, and few levees or water diversions).Process restoration attempts to restore a site by working with existing river processes. This may involve, for example, breaching a levee to reconnect the river to its floodplain behind the levee, or changing landuse, such as cessation of farming or a modified grazing plan, or creating topography by cutting swales or building low berms on the floodplain.

Gauging the Effectiveness of Riparian Buffers

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