The Impact of Auxiliary Spillway Flows from Irene and Lee on NRCS Flood Control Dams in NY

摘要

Rainfall from Tropical Storm Irene (Sept. 2011) caused flows in the six auxiliary spillways on three dams in Greene County, damaging five of the spillways. In one case, erosion in the auxiliary spillway exit channel progressed within 100 feet of the control section. Rainfall from Tropical Storm Lee caused flows in the auxiliary spillways of 19 dams in Broome County without damaging any of the spillways. All of these dams were built as part of PL-566 flood control projects in New York State with assistance from the Natural Resources Conservation Service more than 30 years ago. The storms were analyzed to determine the precipitation amount that caused the depth of flow measured at the control sections. Probable return periods for the storms were determined based on updated precipitation data from the Northeast Regional Climate Center. Measured flows and the resultant damages from erosion in the auxiliary spillway exit channels were compared to predictions of flow and erosion using the SITES program in order to contrast the erosion predicted from the SITES program with the actual erosion that occurred.