Demise of Colonial Mill Dams Linked to Increased Rates of River Bank Erosion, South River, Virginia

Pizzuto, J.E. and O'Neal, M., 2009, Increased mid-20th century bank erosion rates related to the demise of mill dams, South River, Virginia.  Geology, v. 37, p. 19-22.

Historical documents reveal the presence of 8 mill dams along the South River in the Shenandoah valley of Virginia.  In the early 20th Century, the river was described as "a series of mill ponds".  By the second half of the 20th Century, all of these mill dams had been breached.


Studies of historical aerial photographs demonstrate that rates of bank erosion increased after 1957 along the South River. The increase cannot be explained by the frequency of freeze-thaw or high discharges, or by changes in riparian vegetation.  


Backwater modeling suggests that loss of the mill dams increased the velocity of a representative 5-year discharge, providing the only available explanation for the observed increase in bank erosion rates at most study sites.


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