이번 달 캘리포니아 남부를 덮친 기록적인 홍수로 미국지질조사(USGS) 소속의 관측소 17곳이 설치된 이래로 최고점의 유량 및 수심을 기록했다. 추가적으로 15곳의 관측소 또한 관측 된 이래 5위 안으로 최고점을 기록했다. Kingstree 타운의 블랙강(Black River)에 위치한 관측소 중 한 곳은 87년만의 최고점을 기록했는데, 이는 강이 1초당 8만3천700㎥의 최고유량을 찍었다는 점을 의미한다.

이전 최고점은 1973년 6월 14일 관측된 기록으로, 국가기상서비스에서 수집된 추가적인 연간 최대 단계데이터 상으로는 1893년 이래로 최고 수준의 유량이다.

 

 

 

During the historic floods in the state of South Carolina this month, 17 streamgages from the U.S. Geological Survey (USGS) recorded the highest peak streamflow and/or river height (or stage) since being installed. An additional 15 streamgages recorded peaks in the top five for their periods of record.

 

One of these streamgages, located on the Black River in the town of Kingstree, recorded its largest peak in the 87 years it has existed. It showed that the river reached a peak streamflow of 83,700 cubic feet per second and a stage of 22.65 feet. The previous maximum on the river occurred on June 14, 1973. Additional annual peak stage data collected by the National Weather Service at the gauge prior to USGS operation indicates this is likely the highest flood since 1893.

 

"This was absolutely an historic flood for South Carolina," said John Shelton, the USGS hydrologist who oversaw the agency's field response and gauging operations in the state. "Throughout the event, we continued to monitor our network of about 170 real-time streamgages, and we sent dozens of teams out in the field to verify what we were seeing. Fortunately, we have quite a few long-standing streamgages in South Carolina, so we can put these floods into historical context."

 

One of the longest-running streamgages in South Carolina is located on the Congaree River in Columbia, with annual records back to 1892 and even flood information for 1852. That means that there are 123 years of record to place the October floods into perspective. The gauge peaked at 185,000 cubic feet per second at a peak stage of 31.8 feet on October 4. When compared to the historical flood record, this peak ranks eighth out of 123 years of record with the peak of record being 364,000 cubic feet per second at a peak stage of 39.8 feet on August 27, 1908.

 

However, the October flood on the Congaree River is the highest since April 8, 1936, when the river peaked at 231,000 cubic feet per second at a peak stage of 33.3 feet. For comparison, an Olympic-sized swimming pool contains 88,000 cubic feet, so the most recent peak on the Congaree River at Columbia would fill a little over two Olympic-sized swimming pools every second.

 

Throughout the entire flood, the USGS deployed nearly 100 people who collected almost 250 distinct streamflow measurements in South Carolina, North Carolina and Georgia; deployed and recovered storm-tide sensors and Rapid-Deployment Gauges; and flagged and determined the elevation of close to 600 high-water marks in support of response and recovery missions for FEMA.

 

The effort, led by the USGS South Atlantic Water Science Center, which has offices in South Carolina, North Carolina and Georgia, was supported by teams from other USGS offices in Alabama, Florida, Mississippi, and Pennsylvania. A total of eight streamgages were destroyed or damaged during the floods in South Carolina, with five replaced with Rapid-Deployment Gauges within hours of the gauge outage.

 

In South Carolina, the teams made about 140 streamflow measurements at about 86 real-time streamgages to verify or update existing information on streamflow at that site. This information, along with a comparison of historic peak flows or stages and a chronology of major flood events in South Carolina since 1893, is available in a new USGS report, titled "Preliminary Peak Stage and Streamflow Data at Selected USGS Streamgaging Stations for the South Carolina Flood of October 2015."

 

[출처 = Water World / 2015년 10월 22일]