SGER: Hurricane Katrina and Lessons for Responding and Repairing Catastrophic Levee Failures Applicable to Other Similarly Threatened Areas in the U.S.

来自加州大学伯克利分校的traymond B. Seed，“SGER：卡特里娜飓风和应对和修复适用于美国其他类似威胁地区的灾难性堤坝故障的经验教训”技术专家早就预见到，飓风可能会导致防洪堤发生灾难性破坏，进而导致新奥尔良洪水泛滥。然而，新奥尔良并不是美国唯一一个存在这种灾难性灾害的地区，但在很大程度上没有得到解决。加州也存在着惊人的类似情况，由于脆弱的迷宫般的堤坝安全通过了加州三分之二重要淡水的关键节点，因此潜在的灾难性地震风险也与之相关。萨克拉门托市目前是北美最大的城市地区，堤防防洪水平最低。额外的关键堤防系统为整个密西西比河和俄亥俄河流域以及查尔斯顿地区和美国其他地区提供洪水保护。从新奥尔良堤防系统的表现以及紧急修复和抽水使被淹没地区脱水的关键经验教训是至关重要的。虽然在紧急修复孤立断口方面有相当多的经验，但新奥尔良灾难是提供军事资产以协助紧急修复的前所未有的实例。这一活动首次为定量评估此类作业的价值和影响提供了机会，而不是更传统地使用驳船倾倒岩石和疏浚填土，或使用陆地运输和设备运输和放置新的填土。研究人员将调查各种堤坝决口的冲刷侵蚀程度，并将其与超大型直升机载“沙袋”的放置率进行比较。该小组将调查与承包有关的问题和实地放置材料的困难。其他因素包括渗漏以及紧急修复部分的沉降和沉降。匆忙修复的长期表现是问题的一个重要因素，就像永久性修复将受到非常规应急堤坝“补丁”存在的影响的程度一样。其他将被调查的问题包括风浪对被淹堤坝背面的侵蚀程度，由于部分和风浪驱动的溢水而对未被破坏的堤坝部分造成的侵蚀和破坏程度，以及堤坝的配置、波峰和上表面保护细节，以及它们与浪涌驱动的水位和风浪的相互作用。另一组将被研究的问题是堤防的设计和配置，以及它们在这次事件中的整体表现。许多关键的堤坝并没有倒塌，这些也代表了重要的教训。导致当前堤防配置的设计基础和决策过程也是将被调查的关键因素。至关重要的是，要从进行和监督维修工作的工程师和人员那里吸取这些经验教训，并将这些经验教训有效地传递给其他地区的大堤维修专家、应急规划人员和风险评估专家。这些经验教训可以提高速度和效率，因此在规划应对大型（灾难性）紧急情况时非常宝贵。这个跨学科团队得益于美国土木工程师协会和加州水资源部的协同努力和/或资助。团队成员多元化，包括全国公认的防洪堤专家和在自然灾害领域的杰出经验。卡特里娜飓风过后，对新奥尔良地区防洪堤性能的调查将为美国大部分地区关键防洪堤系统的未来性能提供重要信息

ABSTRACTRaymond B. Seed, University of California, Berkeley"SGER: Hurricane Katrina and Lessons for Responding and Repairing Catastrophic Levee Failures Applicable to Other Similarly Threatened Areas in the U.S." The potential for hurricane-induced catastrophic failure of the levees and subsequent flooding of New Orleans had long been foreseen by technical experts. However, New Orleans is not the only region in the United States in which this type of catastrophic hazard exists, but goes largely unaddressed. A stunningly similar situation exists in California with regard to potentially catastrophic seismic risk associated with the fragile labyrinth of levees that pass two-thirds of California's vital fresh water safely through the key node in the State's extensive water distribution system. The city of Sacramento is currently the largest metropolitan area with the lowest level of levee flood protection in North America. Additional critical levee systems provide flood protection throughout the Mississippi and Ohio River basins, as well as in the Charleston area, and in other regions of the U.S.There are key lessons of vital importance to be learned from the performance of the New Orleans levee systems, and the emergency repair and pumping to dewater the inundated areas. Although there is considerable experience in the emergency repair of isolated breaks, the New Orleans disaster represents an unprecedented instance in which military assets were made available for assisting in emergency repairs. This event provides the first opportunity to quantitatively assess the value and impact of such operations as opposed to more traditional use of barges to dump rock and dredged fill, or land-borne transport and equipment to carry and place new fill soils. The degree of scour erosion at the various levees breaks will be investigated and compared to placement rates of oversized helicopter-borne "sand bags." The team will investigate issues related to contracting and difficulties in the field placement of material. Additional elements include the seepage as well as settlement and subsidence of the emergency repaired sections. Long term performance of the hurried repairs is an important element of the problem, as is the degree to which permanent repairs will be affected by the presence of the unorthodox emergency levee "patches." Other issues that will be investigated include the degree to which wind driven waves eroded the back faces of the flooded levees, the degree of erosion and damage caused in non-breached levee sections due to partial and wave-driven overtopping, and the levee configurations and crest and upper face protection details, and their interaction with surge-driven water levels and wind-driven waves. Another set of issues that will be studied are the levee designs and configurations, and their overall performances in this event. Many critical levees did not fail, and these represent important lessons as well. The design basis and decision process that led to the current levee configurations are also key elements that will be investigated.It is vital to absorb these lessons from the engineers and personnel who performed and oversaw the repairs, and that these lessons be effectively transmitted to levee repair experts, emergency planners, and risk assessment experts in other regions. These lessons can improve speed and efficiency and thus are invaluable in planning the response to large (catastrophic) emergencies. The interdisciplinary team benefits from the synergistic efforts and/or funding from the American Society of Civil Engineers and the California Department of Water Resources. The team members are diverse and include nationally recognized levee experts and outstanding experience in the field of natural disasters. The investigation of the performance of the New Orleans area levees in the aftermath of the Hurricane Katrina will provide vital information for the future performance of critical protective levee systems throughout large areas of the U.S.