As forecasts tracked Hurricane Harvey's course toward Houston last week, researchers in Vicksburg, Mississippi were already calculating the flooding impacts from the storm to better inform the U.S. Army Corps of Engineer's Emergency Operations team.

A team of researchers from the U.S. Army Engineer Research and Development Center are forecasting inundation depths in and around Houston up to five days in advance using technology developed at ERDC.

The team modeling Harvey's impacts includes experts and assets from the Coastal and Hydraulics Laboratory and supercomputing resources from the Information Technology Laboratory. Aaron Byrd, research civil engineer in CHL, has been leading the ERDC effort.

"We're constantly running models based on new forecasts looking three to five days out," Byrd said. "It takes a lot of effort. Right now 18-hour days are not uncommon."

Using one of two supercomputers at ERDC's Vicksburg campus, Byrd and his fellow researchers are modeling inundation depths in Houston along Buffalo, Brays and White Oak Bayous, around Addicks and Barker Dams, as well as the upstream areas of the dams where rainfall is feeding into the river system.

The models were initially based off earlier efforts examining flooding from Tropical Storm Allison that hit Houston in June 2001, but needed updating to meet the urgent needs of disaster preparedness and response.

"We'd done a test case for Tropical Storm Allison a few years ago," Byrd said. He noted that, while they had something to start from, a wealth of new data and drastically different flood conditions meant almost completely rebuilding the model from the ground up.

Since Friday, Byrd and the ERDC team have been constantly running and refining simulations using the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) modeling technology developed here at ERDC to simulate the watershed. GSSHA is a multidimensional modeling engine that tightly couples overland, surface, and subsurface flow to accurately simulate watershed physics.

GSSHA models have been used by researchers in CHL to study the effects of storm surge and sea-level change on coastal military facilities and cities. In October 2012, the Corps of Engineers used GSSHA to model the inland effects of the combined high storm surge, modeled by CHL's Chris Massey, and the rainfall from Superstorm Sandy on New York City and Long Island. Mayor Michael Bloomberg used this information to evacuate coastal and low-lying areas in New York City and plan for the coming disaster.

Information from the models - as well as data from modeling teams led by Massey at ERDC and Robert Simrall of the Corps' Modeling, Mapping, and Consequences Production Center at the Vicksburg District office - is provided to the U.S. Army Corps of Engineers Operations Center in Washington, D.C., to keep first responders and decision makers safe and informed.

The U.S. Army Engineer Research and Development Center is the research organization of the U.S. Army Corps of Engineers. ERDC conducts R&D in support of the Soldier, military installations, and civil works projects as well as for other federal agencies, state and municipal authorities, and with U.S. industry through innovative work agreements. ERDC research develops innovative solutions for a safer, better world.

To learn more about the GSSHA technology, visit: http://www.erdc.usace.army.mil/Media/Fact-Sheets/Fact-Sheet-Article-View/Article/476714/gridded-surface-subsurface-hydrologic-analysis/