DELAWARE RIVER BASIN COMMISSION

Erosion

Excessive stream erosion can be caused by many factors. Major impacts are channel realignment, increasing volumes and frequency of peak flows, loss of flood plains, and loss of streambank vegetation. Increasing volumes and frequency of peak flows generally follow increasing urbanization (Schueler, 1995). Loss of flood plains, which are now protected by regulations, may have occurred by past encroachment. Examples of eroding streambanks due to loss of protective streambank vegetation are commonplace in the basin.

An example of a reasonably well vegetated streambank: Dunnfield Creek, upstream of Interstate Route 80, Worthington State Forest, Warren County, NJ. Note the woody debris and trees which create canopy. Sweeney (1992) reported on the value of streamside forests to contribute organic carbon compounds to the food chain and the value of the shaded streams to produce more desirable algae.

An example of eroding streambanks adjacent to a pastured field: Alexauken Creek, looking downstream of U.S. Route 202, Delaware Township, Hunterdon County, NJ.

In addition to streambanks, there are numerous swales and roadside ditches with eroding banks.

Stormwater drainage swale to Reeders Creek, State Police Drive, Ewing Township, Mercer County, NJ. This deeply eroded drainage swale, located near the Commission offices, discharges an unknown amount of streambank soil to the creek, a tributary of the Delaware River.

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