Mitigating land loss in coastal Louisiana by controlled diversion of Mississippi River sand
Mitigating land loss in coastal Louisiana by controlled diversion of Mississippi River sand
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DOI：
10.1038/ngeo1525
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发表时间：
2012-08
影响因子：
18.3
通讯作者：
J. Nittrouer;J. Best;C. Brantley;R. Cash;M. Czapiga;Praveen Kumar;G. Parker
中科院分区：
文献类型：
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作者：
J. Nittrouer;J. Best;C. Brantley;R. Cash;M. Czapiga;Praveen Kumar;G. Parker
1927 年密西西比河发生创纪录的洪水后，路易斯安那州修建了 Bonnet Carré 溢洪道作为防洪工程。当溢洪道开放时，洪水将从密西西比河转移到庞恰特雷恩湖，以减少流经新奥尔良的水流量。 2011 年密西西比河洪水期间，发生了自 1927 年以来的最高流量峰值，邦尼卡雷溢洪道从 5 月 9 日到 6 月 20 日开放了 42 天。在此期间，溢洪道平均流量为6,010 m3s−1，占河流洪水总流量的10%~20%。在此，我们展示了 2011 年密西西比州洪水之后泄洪道中新沉积物的面积范围和厚度的测量结果。只有上部 10-15% 的河流水柱被撇入泄洪道。然而，我们保守估计，在溢洪道开放期间，密西西比河携带的总沙量的 31-46% 被改道。我们发现当地河流状况导致上部水柱中悬浮沙的浓度增加，从而导致沙子从河流转移到溢洪道中。我们的结论是，路易斯安那州工程河流改道的适当设计可以帮助减轻沿海湿地损失。
After the 1927 flood of record on the Mississippi River, the Bonnet Carré Spillway in Louisiana was constructed as a flood control operation. When it is opened, the spillway diverts floodwaters from the Mississippi River to Lake Pontchartrain, to reduce the water discharge flowing past New Orleans. During the 2011 Mississippi River flood, which had the highest peak discharge since 1927, the Bonnet Carré Spillway was opened for 42 days, from 9 May to 20 June. During this period, the average spillway discharge of 6,010 m3s−1amounted to 10–20% of the total river flood discharge. Here we present measurements of the areal extent and thickness of new sediments in the floodway, following the 2011 Mississippi flood. Only the upper 10–15% of the river water column was skimmed into the floodway. Yet, we conservatively estimate that 31–46% of the total sand load carried by the Mississippi River during the period of spillway opening was diverted. We find that local river conditions led to increased concentrations of suspended sand in the upper water column and thus led to diversion of sand from the river into the spillway. We conclude that an appropriate design of engineered river diversions in Louisiana can help mitigate coastal wetland loss.