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South Carolina governor declares state of emergency after record rainfall


October 6, 2015   by Canadian Underwriter


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South Carolina Governor Nikki Haley has declared a state of emergency for the state, as flash flood warnings were issued for Berkeley, Charleston and Dorchester in anticipation of rainfall between 10 and 15 inches.

A business is destroyed by flooding in Columbia on Oct. 5, 2015. Chuck Burton / AP

Much more rain than that already fell in many towns in those counties, catastrophe modelling firm AIR Worldwide said in a press release on Monday. “Rainfall records in South Carolina fell nearly as fast as the rain itself, including many for Charleston alone, such as greatest one-day rainfall, which was 11.5 inches at Charleston Airport on Oct. 3,” said Dr. Marc Marcella, a scientist at AIR Worldwide, in the release. “Records for two- and three-day rainfall were also set with slightly higher amounts. The greatest monthly October rainfall record for both the airport and downtown were set with 16.01 inches and 14.25 inches, respectively, as of the afternoon of Oct. 4—very early in the month.”

Many towns in Berkeley, Charleston, and Dorchester counties received more than 10 inches of rain, with Mount Pleasant in Charleston County receiving 24.23 inches of rainfall (the most of any town in the Tri-County area), AIR Worldwide reported. The town of Huger in Berkeley County receiving 21.04 inches and Summerville in Dorchester County received 17.23 inches between 7 a.m. on Oct. 1 and 9 a.m on Oct. 4. In addition, the city of Columbia in Richland County reported a one-day rainfall record of 7.77 inches.

“An extensive band of tropical moisture produced a slow-moving, northwest-to-southeast swath of rainfall across the Carolinas,” explained Dr. Marcella. “Flooding rains were exacerbated by the fact that the band’s movement was nearly parallel with the band’s center axis of orientation. The atmospheric setup that led to the nearly stationary and localized rainfall can most likely be linked to a strong high pressure system across southeastern Canada, the closed low pressure across the region, and Hurricane Joaquin.”

Joaquin added that the trend has been for the heaviest rainfall to move from the southwest to the northeast, with the current strongest banding now occurring across North Carolina.

This past weekend’s heavy rains are responsible for closing hundreds of roads throughout the eastern part of South Carolina, including a 75-mile section of I-95 and parts of U.S. 17A and U.S. 52, the release said. In addition, 127 bridges in the state were closed as well as most schools in the Tri-County area.

The University of South Carolina in Columbia, where there is a mandatory curfew in force, was closed after it was cut off from its water supply. There were also many dam breaches, which exacerbated flooding conditions, and power and water were cut off to thousands.

Businesses were closed due to flooding and hundreds of people were rescued from their homes or vehicles in the Tri-County area over the past weekend.

According to AIR Worldwide, South Carolina has a long history of flooding due to the combined impact of atmospheric conditions and a lack of proper maintenance of flood control and drainage systems. Flood control mitigation efforts have been in place for many years, but South Carolina has a significant number of vulnerable structures despite these efforts.

Approximately 85% of the residential construction is wood, with an estimated 20% having basements, the release noted. The presence of a basement increases the risk for contents and building damage. More than half of the commercial buildings are steel and concrete; unlike residential structures, these buildings often have engineering attention and are built to stricter standards, but are nevertheless susceptible to high water flow velocities.

“Precipitation of 3-5 inches has been forecast for today in the areas already affected, with the heaviest rainfall now moving into North Carolina,” Dr. Marcella said. “Flash flood threats continue in the Tri-County area in South Carolina, and will increase across Pender and southeast Bladen counties in North Carolina today. However, Tuesday and Wednesday are predicted to be drier.”


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