43:. On March 12, 2004 the Big Bay dam embankment failed through piping in the vicinity of the principal spillway 12 years after construction. A peak breach flow of 147,000 ft/s (4,200 m/s) was estimated from the breach geometry, breach timing and the reservoir volume. The Big Bay embankment, which is largely intact, is approximately 1890 feet long and 51.3 feet high. The failure occurred with an initial water surface about 6 inches (0.15 m) above the normal pool elevation of 278.0 ft (84.73 m), releasing 14,200 ac-ft (17,500,000 m) of water and inundating 14.3 miles (23.0 km) of valley to depths of up to 33 ft (10 m) from the dam to the Pearl River. Woody material was stripped from the stream valley for a length of 2300 ft (700 m) immediately below the dam, after which velocities decreased to such an extent that little vegetation was uprooted.
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regard to the breach timing, increased discharge from a pre-existing seep was first noticed on
Thursday, March 11. The seep gradually increased its discharge, with the flow carrying material by the next morning. At mid-morning on March 12 the seep was inspected and was noticed that it had about a ½ inch of head height. By 12:15 water “shot up out of the hole”. Shortly after this the seep was observed to be “spouting approximately 2 to 3 ft in height, with a diameter of about 18 inches”. The area around the boil then collapsed and the embankment began to rapidly erode. This is the point where the breach is assumed to start, at about 12:20. The final breach dimensions occurred from about 13:10. Full formation is assumed to occur at 13:15—the breach formation time is estimated to be 55 minutes.
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damage, 1 mobile home was destroyed, 3 mobile homes had major damage, 3 mobile homes had minor damage, Pine Burr Church suffered major damage, Hub Chapel Church had minor damage, and the
Pinebur Volunteer Fire Department suffered major damage. In all, 104 structures were documented as damaged or destroyed. There were no deaths.
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The dam breach characteristics, specifically the breach geometry and formation time, were estimated by Yochum et al. 2008. The breach width was measured to be 230 ft (70 m), with a top width of 315 ft (96 m), right side slope of 0.61 and a left side slope of 1.3 (horizontal/vertical). In
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Counties. A damage assessment indicated that, within Lamar County, 26 homes were destroyed, 8 homes had major damage, 8 homes had minor damage, 25 mobile homes were destroyed and 1 mobile home had minor damage. In Marion County, 1 home was destroyed, 13 homes had major damage, 12 homes had minor
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MEMA. 2004. “NEWS: Governor
Barbour requests federal assistance.” News release, Mississippi Emergency Management Agency, March 22, 2004.
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Yochum, S.E.; Goertz, L.A.; Jones, P.H. (2008). "Case Study of the Big Bay Dam
Failure: Accuracy and Comparison of Breach Predictions".
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Burge, T.R. (2004) Big Bay Dam: Evaluation of
Failure Land Partners Limited Partnership, Hattiesburg, MS.
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Report from
National Oceanographic and Atmospheric Administration (NOAA) in Jackson, MS
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The inundation impacted Bay Creek and Lower Little Creek in Lamar and
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Buildings and structures in Lamar County, Mississippi
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66:photo shows some damage caused by the flood
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20:The breach is clearly visible in this
214:2004 disestablishments in Mississippi
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209:1991 establishments in Mississippi
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184:Dam failures in the United States
91:Journal of Hydraulic Engineering
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35:located 11 miles west of
194:Disasters in Mississippi
204:Dams completed in 1991
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189:Dams in Mississippi
160:31.1826°N 89.5712°W
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37:Purvis, Mississippi
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33:earthen dam
29:Big Bay Dam
178:Categories
151:89°34′16″W
148:31°10′57″N
71:References
24:photograph
62:Another
31:was an
48:Marion
64:NOAA
22:NOAA
99:doi
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