DATE: September 17, 2008

CONTACT: Anand Jayakaran, 843-546-1013, ext. 223
ajayaka@clemson.edu

CONTACT: Dan Hitchcock, 843-546-1013, ext. 236
dhitchc@clemson.edu

WRITER: Peter Hull, 843-554-7226, ext. 118
phull@clemson.edu

Clemson researchers could help spare future Georgetown development from flooding

GEORGETOWN — Before the trees come down and houses rise in their places, two Clemson scientists at the Baruch Institute of Coastal Ecology and Forest Science want to protect future developments from the risks of flooding.

Professors Anand Jayakaran and Dan Hitchcock are working to determine what pre-development hydrologic conditions exist in coastal watersheds; in this case, the historic Bannockburn Plantation nestled between U.S. 17 and the Atlantic Ocean in Georgetown County.

Their mission is simple: control stormwater quantity and quality as if the bulldozers never moved in.

Today the test site is relatively pristine, with many natural streams and habitat; the ideal time to measure water quality and track how water moves within and across the watershed.

As part of a long-term study within Bannockburn, also referred to as the Arcadia East property, the researchers have constructed three 2-by-10 water flumes in a drainage area that measure three-fourths of a mile square.

If the site one day has homes or businesses, their research could help prevent those structures from flooding.

The Parshall flumes, named for their inventor, Ralph L. Parshall, are placed strategically throughout the watershed, with one at the watershed's headwaters, the second at its midway point and the third at the watershed outlet.

Development or not, stormwater has to go somewhere. It typically enters the soil as groundwater or results in surface stream flow, a common occurrence when the soil is saturated.

"Because this property is slated for development in the next 10 years we anticipate that as hard surfaces are added as a function of development — such as roads, buildings, parking lots — the hydrology will be affected," Jayakaran said.

It means stormwater will be unable to penetrate the ground as it used to, slowing down in the process. Rather, any runoff from development will speed up and seek the nearest stream. As it continues, the water will be diverted by the new hard surfaces, possibly causing flooding downstream.

"It'll be forced to go somewhere else," Jayakaran said.

Developers are mandated to ensure they mimic pre-development hydrological conditions to prevent flooding. But often those pre-development conditions are not specific to the site and instead are based on studies from other parts of the country.

The study by Jayakaran and Hitchcock will establish a baseline for future developers to follow.

And that's where the flumes come in. They provide a uniform cross-section in the stream, whereas natural stream beds are uneven and have many undulations.

By constructing the flumes to exact dimensions, the researchers can measure the amount of water that passes through them and determine the pollutant load: the amount of pollutant, such as bacteria and sediment, contained within that water volume.

At two of three locations, Hitchcock has installed automated water samplers that can be programmed to take samples at timed interval or triggered based on flow or rainfall.

Hitchcock analyzes the samples for pathogenic bacteria and nutrients, such as nitrogen and phosphorus. He also continually measures temperatures, pH, conductivity and dissolved oxygen in the streams.

Jayakaran and Hitchcock expect their findings could be transferred beyond the study site to areas of similar landscape commonly found in neighboring Georgia and North Carolina and areas of Florida.

"There are numerous coastal tracts being developed that have similar hydrology, habitats and landscapes," Hitchcock said.

END