A Delicate Balance of Stormwater Management Upstream and Downstream of Lake Whitehurst: 1D-2D H&H Study

Lesley Brewer, EIT, Assistant Engineer II, Hazen and Sawyer

Michael Barbachem, PE, BCEE, Senior Associate, Hazen and Sawyer

Justin Shafer, Coastal Resilience Manager, City of Norfolk

Lake Whitehurst is a drowned estuary impounded in the early 1900s to create a drinking water reservoir for the City of Norfolk. Since the initial impoundment, the dam spillway has been modified to include notches and removable stop logs to seasonally control the normal pool elevation of the lake. Today, Lake Whitehurst covers an area of 477 acres and collects stormwater flow from nearly 3,000 acres of contributing drainage area, influencing the stormwater drainage of several neighbors including adjacent residential neighborhoods, the Norfolk International Airport, Norfolk Botanical Gardens, Joint Expeditionary Base Little Creek (JEB Little Creek), and other areas through interconnections with Lake Wright, Little Creek Reservoir, Lake Smith, and Lake Lawson.

The City of Norfolk expanded and refined an existing model to develop an integrated 1D-2D PCSWMM model of the Lake Whitehurst watershed. Combined with the existing model, the full model consists of more than 2,900 1D junctions, 1,000 storage nodes, 8,700 1D conduits, and 1,800 subcatchments.

This effort served to understand the causes of recurrent flooding in the Lake Whitehurst watershed and to provide recommendations regarding both current and future precipitation and/or tidal flooding impacts by evaluating numerous scenarios of varying rain intensities and tidal conditions before and after improvement options. The analysis and evaluation of alternatives required careful attention to the balance between upstream and downstream stakeholders while optimizing the stormwater management function of Lake Whitehurst and avoiding downstream flooding impacts to JEB Little Creek.

Author Bio

Lesley Brewer has 3 years of experience in the water industry, comprising primarily of stormwater design, H&H modeling, and conveyance work. She earned both her M.S. degree in Geosystems Engineering and B.S. degree in Environmental Engineering from the Georgia Institute of Technology. Mike Barbachem is a registered professional engineer with 40 years of experience in environmental and water resources engineering spent almost exclusively in Hampton Roads, Virginia.