Planning for Climate Change: Approach to Estimating and Adapting Flooding Exposure for HRSD Facilities
The Hampton Roads Sanitation District (HRSD) provides wastewater services to 1.7 million people in southeast Virginia. The low topography, regional climatology, and coastal proximity of this region make many of HRSD’s pumping and treatment facilities vulnerable to flooding. This vulnerability is increasing with climate change and rising sea levels, increased storm surge, and greater rainfall recurrence frequency. HRSD facilities are located over a wide expanse of over 3,000 sq. miles, posing a significant challenge to accurately determine flood elevations. To make these large-scale analyses both accurate and practicable, a tiered framework of flood risk evaluation was adopted to account for susceptibility to coastal, pluvial, and/or fluvial flooding. Based on flooding type, site-specific exposure was computed using hydrodynamic models. Storm surge elevations utilized the high-fidelity models employed by USACE for the North Atlantic Coast Comprehensive Study. Pluvial and fluvial flood elevations were determined using two-dimensional hydraulics in HEC-RAS and by expanding on available base flood elevations published by FEMA, respectively. The flooding exposure evaluations completed as part of the HRSD Climate Change Planning Study are intended to support subsequent vulnerability assessment and mitigation analysis planning tasks. The completed analyses can be updated in the future to include additional detail for designing and implementing site-specific mitigation measures.Author Bio
Robert Martz is a Civil Engineer with 26 years of experience in the public utility field. He is currently a Professional Engineer in Virginia and has worked in Florida and Ohio. Prior experience includes the operations, planning, design, and construction of: sanitary sewer pump stations, gravity and pressure mains; along with potable and reclaimed water mains. When he began working for HRSD, he was responsible for coordinating the development of a Regional Hydraulic Model as part of a Consent Decree with the US EPA and 14 local jurisdictions. He is currently working on maintaining the model that HRSD spent close to 10 years developing. He also serves as the lead on HRSD’s climate change planning that is evaluating the impacts of increased rainfall and sea level rise on all of HRSD’s Facilities. He serves as the Chair of the WEF Watershed Management Committee, and also serves on the WEF Program Committee, the WEF Awards Committee, and the WEFTEC Workshop Committee.
