Sea-Level Rise and Subsidence: Implications for Flooding in New Orleans, Louisiana
Sea-Level Rise and Subsidence: Implications for Flooding in New Orleans, Louisiana
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海平面上升和沉降：对路易斯安那州新奥尔良洪水的影响
DOI：
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发表时间：
2003
期刊：
影响因子：
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通讯作者：
David Hart
中科院分区：
文献类型：
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作者：
V. Burkett;D. Zilkoski;David Hart
预计在下个世纪，全球海平面上升速度将加快2到4倍，这会增加低洼、松散的沿海边缘地区的风暴潮和海岸线后退。路易斯安那州东南部的密西西比河三角洲平原由于海岸屏障迅速恶化以及相对较高的地面沉降率，特别容易受到侵蚀和淹没。1951年至1995年间的5个测量时段在新奥尔良大都市区有堤坝防护的区域收集的地表海拔数据显示，平均每年沉降5毫米。其他检测墨西哥湾中北部海岸区域运动的研究的初步结果表明，沉降速度可能高达每年1厘米。考虑到沉降速度以及未来100年海平面上升的中间估计值（480毫米），到2100年，目前低于平均海平面1.5到3米的新奥尔良及其附近地区可能会低于平均海平面2.5到4.0米甚至更多。新奥尔良地区的地表沉降还归因于有机土壤的排水和氧化、与地下水抽取相关的含水层系统压实、表层沉积物的自然压实和脱水以及构造活动（地槽下弯和生长断层沿线的运动）。由于防洪措施以及自然排水通道的破坏减少了新奥尔良地区的沉积物沉积，这个问题更加严重。1. 美国地质调查局，路易斯安那州拉斐特；2. 美国国家海洋和大气管理局，国家大地测量局，马里兰州银泉；3. 威斯康星大学，威斯康星州麦迪逊。海平面加速上升、城市目前的海拔高度以及较高的地面沉降率预示着新奥尔良地区的财产将遭受严重损失，除非防洪堤坝和泵站得到升级。恢复和维护新奥尔良南部和东部的屏障岛屿和湿地是其他可能减少洪水导致的生命和财产损失的应对措施。需要对沉降进行精确监测，以便为路易斯安那州沿海地区的沉降建模和预测提供校准数据，以及为基础设施和堤坝的建设与维护提供支持。全球定位系统技术正在新奥尔良地区进行测试，作为一种更频繁、成本更低的沉降监测手段。
Global sea-level rise is projected to acceler ate twoto four-fold during the next century, increasing storm surge and shoreline retreat along low-lying, unconsolidated coastal margins. The Mississippi River Deltaic Plain in southeastern Louisiana is particularly vulnerable to erosion and inundation due to the rapid deterioration of coastal barriers combined with relatively high rates of land subsidence. Land-surface altitude data collected in the leveed areas of the New Orleans metropoli tan region during five survey epochs between 1951 and 1995 indicated mean annual subsidence of 5 millimeters per year. Preliminary results of other studies detecting the regional movement of the north-central Gulf Coast indicate that the rate may be as much as 1 centimeter per year. Con sidering the rate of subsidence and the mid-range estimate of sea-level rise during the next 100 years (480 millimeters), the areas of New Orleans and vicinity that are presently 1.5 to 3 meters below mean sea level will likely be 2.5 to 4.0 meters or more below mean sea level by 2100. Subsidence of the land surface in the New Orleans region is also attributed to the drainage and oxidation of organic soils, aquifer-system compaction related to ground-water withdrawals, natural compaction and dewatering of surficial sed iments, and tectonic activity (geosynclinal downwarping and movement along growth faults). The problem is aggravated owing to flood-protection measures and disruption of natural drainageways that reduce sediment deposition in the New Orleans area. 1 U.S. Geological Survey, Lafayette, La. 2 National Oceanic and Atmospheric Administration, National Geodetic Survey, Silver Spring, Md. 3 University of Wisconsin, Madison, Wis. Accelerated sea-level rise, the present altitude of the city, and high rates of land subsid ence portend serious losses in property in the New Orleans area unless flood-control levees and pumping stations are upgraded. The restoration and maintenance of barrier islands and wetlands that flank New Orleans to the south and east are other adaptations that have the potential to reduce the loss of life and property due to flooding. Accu rate monitoring of subsidence is needed to provide calibration data for modeling and predicting sub sidence in coastal Louisiana, as well as for support for constructing and maintaining infrastructure and levees. GPS technology is being tested in the New Orleans region as a means for more frequent, less expensive subsidence monitoring.