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WRWP | Strem Assessment

Lower Buck Creek Sub Watershed Drainage Basin Analysis
Using a Bank Erosion Hazard Index (BEHI), Near-Bank Stress (NBS), and Surface Runoff Models to Estimate and Compare Annual Sediment Loads from Soil Erosion
The White River Watershed Project (WRWP), through an EPA Section 319 grant, completed an assessment of soil erosion and sediment loads in the Lower Buck Creek sub watershed. The formal study area was approximately 20,000 LF in Yorktown, Indiana terminating at the confluence of the White River. Field data was collected and analyzed using the Rosgen WARSSS methodology (BEHI and NBS) to determine in-channel erosion rates and annual sediment losses. Publically available models (Region 5 EPA Pollutant Load Reduction, BMP efficiency estimators, STEPL) were utilized to compare sediment contribution to Lower Buck Creek from overland flow.

The Rosgen WARSSS methodology predicted 5,204 tons/year of sediment being eroded from the stream banks (stream bank area estimated at 4.59 acres). Surface runoff models predicted 1,951 tons/year of sediment being transported to the river system (agricultural drainage area approximately 3800 acres). Estimated soil loss at points of extreme BEHI and NBS were predicted as high as 54.5 tons/acre while typical basin-wide surface runoff models predicted 0.5 tons/acre. 20% of the sediment from the stream channel (40,000LF; both banks) was shown to come from only 827LF of stream bank. The results of this study show that stream bank erosion is the major contributing factor to sediment loss rather than surface runoff from surrounding land.

There is a direct relationship between the stream segments on Buck Creek that have been designated as high risk areas for erosion and the presence of rating indicators for “unhealthy streams” (removed riparian vegetation, changes in channel dimension, etc.). Reinstalling bank pins in key locations to further validate these results over time will provide consistent evidence for future bioengineering for this anthromorphic river channel to behave in a natural state; while protecting surrounding land usage, eliminating spending on temporary solutions, and reducing in-channel sediment loss.

































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