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

加州大学伯克利分校的Raymond B.Seed：《SGER：卡特里娜飓风和应对和修复灾难性堤坝的经验教训》适用于美国其他类似受威胁的地区。技术专家早就预见到飓风引发的灾难性堤坝坍塌和新奥尔良洪水泛滥的可能性。然而，新奥尔良并不是美国唯一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。加利福尼亚州存在着惊人的类似情况，与脆弱的迷宫堤坝有关的潜在灾难性地震风险，使加州三分之二的重要淡水安全地通过该州广泛的供水系统的关键节点。萨克拉门托市是目前北美堤防防洪水平最低的最大大都市区。其他关键堤防系统在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防洪保护。从新奥尔良堤防系统的性能以及紧急修复和抽水对淹没地区的排水中吸取了至关重要的关键经验教训。虽然在紧急修复孤立断口方面有相当多的经验，但新奥尔良的灾难是一个史无前例的例子，可以动用军事资源协助紧急修复。这一活动提供了第一次定量评估此类作业的价值和影响的机会，而不是更传统地使用驳船倾倒岩石和疏浚填土，或使用陆上运输和设备来运送和放置新的填土。将对不同堤防决口的冲刷侵蚀程度进行调查，并将其与超大直升机携带的“沙袋”的安置率进行比较。该小组将调查与承包有关的问题和实地安置材料的困难。其他因素包括渗漏以及紧急修复路段的沉降和下沉。匆忙抢修的长期表现是问题的一个重要因素，永久抢修将在多大程度上受到非正统紧急堤防“补丁”的影响也是一个重要因素。其他将被调查的问题包括：风浪对被淹堤防背面的侵蚀程度；局部和海浪漫顶对未决口堤段造成的侵蚀和破坏程度；堤防配置、堤顶和上表面防护细节，以及它们与浪涌水位和风浪的相互作用。另一组将研究的问题是堤防的设计和配置，以及它们在这项赛事中的整体表现。许多关键的堤坝并没有坍塌，这些也是重要的教训。导致当前堤防配置的设计基础和决策过程也是将进行调查的关键因素。从进行和监督修复的工程师和人员那里吸取这些教训至关重要，并将这些教训有效地传递给其他地区的堤防修复专家、应急规划者和风险评估专家。这些经验教训可以提高速度和效率，因此在规划应对大规模(灾难性)紧急情况方面非常宝贵。跨学科团队受益于美国土木工程师学会和加州水资源部的协同努力和/或资金。小组成员多种多样，包括国家公认的堤防专家和在自然灾害领域的杰出经验。对卡特里娜飓风过后新奥尔良地区堤防性能的调查将为美国大片地区关键防护堤系统未来的性能提供重要信息。

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.