Flood Inundation Maps for Elmira, Corning, Chemung, and Erwin, New York, November 2019
The Chemung River flows from Steuben County, New York, through Chemung County, New York, to its confluence with the Susquehanna River just below Athens, Pennsylvania. Hurricane Agnes in June 1972 devastated the region and remains the flood of record in this portion of the Susquehanna River Basin. Completed in 1980 and 1978, respectively, and subsequent to Hurricane Agnes flooding, the United States Army Corps of Engineers (USACE) constructed the Cowanesque and Tioga-Hammond flood control reservoirs. The flood control reservoirs supplement a system of levees in the region and have significantly reduced the threat of flooding in the region. However, flood risk remains a deep concern, thereby necessitating development of tools to inform and promote awareness of flood risk in the region.
This report describes development of a non-structural flood hazard mitigation tool to inform the general public, community officials, and emergency managers of risk associated with high flow events in the study reach. The tool is a set of stage inundation map libraries for the Chemung River based on National Weather Service (NWS) flood forecast points located at Chemung, Corning, and Elmira. Additionally, a map library is available for the Tioga River near Erwin, a NWS data only point, but no forecast is available. The stage inundation map libraries have been created for display on National Oceanic Atmospheric Administration’s Advanced Hydrologic Prediction Service (NOAA AHPS) map viewer site. The inundation maps provide a graphical extension to river forecasts issued by NWS for the Chemung River and for the Tioga River near Erwin, where no forecast is available, and can be used to understand impacts associated with varying levels of flooding.