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RAPID: Sediment, water, and nutrient flux and fate in Lake Pontchartrain from the 2011 Bonnet Carre Spillway Opening.

RAPID：2011 年 Bonnet Carre 溢洪道开放后庞恰特雷恩湖的沉积物、水和营养物通量及归宿。

基本信息

批准号：
1139997
负责人：
Samuel Bentley
金额：
$ 10万
依托单位：
Louisiana State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2011
资助国家：
美国
起止时间：
2011-06-15 至 2013-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1139997&HistoricalAwards=false
关键词：
RAPID Sediment water nutrient flux

项目摘要

RAPID: Sediment, water, and nutrient flux and fate in Lake Pontchartrain from the 2011 Bonnet Carre Spillway OpeningEAR-1139997Samuel Bentley, Sibel Bargu, Chunyan Li, Nan Walker, John R. WhiteLouisiana State UniversityABSTRACTThe lower Mississippi River Delta (MRD), inhabited by 2 million people, is a critical national resource in terms of maritime transport, fisheries, and energy. MRD wetlands and waters are degrading at alarming rates, losing wetlands equivalent to the area of Delaware since the 1930?s, and more over the next century. The health of coastal waters and the fate of wetlands are strongly governed by the flow of fresh water and accompanying sediments and nutrients, which are now largely controlled by engineered structures along the river. For these reasons, conservation and restoration of the MRD is one of the outstanding environmental and socioeconomic challenges faced by our country over the next century. Understanding and managing water, sediment, and nutrient flux and fate into the MRD coastal zone is central to this challenge. The Spring 2011 hydrograph of the Mississippi River is reaching levels exceeding the Great Flood of 1927 in many locations in Louisiana. To provide relief to river levees, water is being released through the Bonnet Carré Spillway (BCS) into Lake Ponchartrain (LP), a large mostly enclosed estuary within the MRD (Fig. 1). BCS opening on May 9 is now producing record fluxes of water (8800 m3 s-1, 126% of design capacity) into LP, likely along with record fluxes of sediment and nutrients. Understanding the dynamics and impact of this plume in LP is important for several reasons: (1) nutrient loading to the lake will produce potentially toxic algal blooms; (2) fresh water flux will cause strong exchange of the fresher lake with the saltier coastal ocean; and (3), measurement and study of sediment supply and deposition will provide important information for use of sediment in engineered diversions for delta restoration. PIs will sample water, sediment, nutrients, and plankton over time to understand impacts to the lake, in order to better understand impacts from future manmade diversions for delta restoration. Because LP has strong similarities to other MRD estuaries, and engineered diversions of river water and sediment are primary tools planned for MRD conservation and restoration, results of this work will be directly applicable to large regions of the MRD in need of conservation and restoration.

密西西比河下游密西西比河三角洲(MRD)拥有200万人口，在海上运输、渔业和能源方面是一个重要的国家资源。MRD湿地和水域正在以惊人的速度退化，自1930年以来失去的湿地面积相当于特拉华州的面积？S，并在下个世纪失去更多。沿海水域的健康和湿地的命运在很大程度上取决于淡水及其伴生的沉积物和营养物质的流动，目前这些物质主要由沿河的工程建筑控制。出于这些原因，保护和修复MRD是我国在下个世纪面临的突出环境和社会经济挑战之一。了解和管理进入MRD海岸带的水、沉积物和营养物质的通量和命运是这一挑战的核心。在路易斯安那州的许多地方，2011年春季密西西比河的水位正在达到超过1927年大洪水的水平。为了向河堤提供救济，水正通过Bonnet Carré溢洪道(BCS)释放到庞查特雷恩湖(LP)，这是MRD内的一个主要封闭的大型河口(图1)。BCS于5月9日启用，目前正在产生创纪录的流入低压的水通量(8800立方米S-1，设计容量的126%)，可能还有创纪录的沉积物和营养物质通量。了解这种羽流在LP中的动态和影响非常重要，原因有几个：(1)向湖泊中装载营养物质将产生潜在的有毒藻类水华；(2)淡水通量将导致较新鲜的湖泊与较咸的沿海海洋进行强烈交换；以及(3)沉积物供应和沉积的测量和研究将为在工程改道中利用沉积物进行三角洲恢复提供重要信息。PIS将随着时间的推移对水、沉积物、营养物质和浮游生物进行采样，以了解对湖泊的影响，以便更好地了解未来人工改道对三角洲恢复的影响。由于LP与其他MRD河口有很大的相似之处，而工程改道河流水和泥沙是MRD保护和恢复计划的主要工具，这项工作的结果将直接适用于需要保护和恢复的MRD的大片区域。