Causation and avoidance of catastrophic flooding along the Indus River, Pakistan
Causation and avoidance of catastrophic flooding along the Indus River, Pakistan
复制标题
巴基斯坦印度河沿岸灾难性洪水的成因和避免
DOI：
10.1130/gsatg165a.1
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
G. Brakenridge
中科院分区：
文献类型：
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作者：
J. Syvitski;G. Brakenridge
2010 年印度河沿岸的灾难性洪水从 7 月开始，高地流域出现了异常强烈但并非史无前例的降雨。四个月内，近 2,000 人死亡，约 20,000,000 名居民流离失所。气象事件引发但并未造成这场“自然”灾害。多时相遥感和地形分析表明，大部分损害是由大坝和拦河坝相关的回水效应、输水输沙能力下降以及灌溉系统堤坝多次失效造成的。大量的故障从发生了一些创纪录流量的上游地区延伸到峰值流量并不极端的下游河段和三角洲。巴基斯坦信德省发生了两次重大河流撕扯（水流位置突然改变）。其中一次（北部撕裂），印度河水淹没了约 8,000 公里的农田，深度达 1-3 m；部分河流流向洪水前所在地以西 50 至 100 公里处。这次撕扯是由于 8 月 6 日至 7 日，苏库尔拦河坝上游的人工堤坝 Tori Bund 决口造成的，此时距离第一个洪水顶峰到来的前两天，以及早在 8 月 24 日上游 100 公里的查查兰 (Chacharan) 达到峰值河水流量之前。在洪水上涨阶段，早期的决口使得大部分即将到来的洪水波在持续一段时间内为撕裂提供动力。正如 2008 年印度科西河发生的戏剧性的暂时性撕脱事件一样，由于缺乏针对河流高泥沙量的计划调节措施以及河流高于周围地形的超高海拔，导致了异常危险的堤坝溃决和河道撕脱。无论洪水预警是否得到改善，在大洪水事件期间，河流流量的重大转移将继续发生。观察到的动态表明，加固现有工程结构并不是避免未来洪水灾害的可持续策略。相反，需要对主要的水流和泥沙分流进行规划，以有效控制印度河和其他沉积物丰富且容易发生撕扯的河流沿岸的洪水。
The catastrophic flood of 2010 along the Indus River began in July with unusually intense but not unprecedented rainfall in the upland catchment. During four months, close to 2,000 fatalities occurred and ~20,000,000 inhabitants were displaced. The meteorological events triggered but did not cause this “natural” disaster. Analysis of multi-temporal remote sensing and topography instead indicates that most damage was caused by dam and barrage-related backwater effects, reduced water and sediment conveyance capacity, and multiple failures of irrigation system levees. The numerous failures extended from upstream areas, where some record discharges occurred, to downstream reaches and the delta, where peak discharges were not extreme. In Sindh, Pakistan, two major river avulsions (sudden changes in flow location) occurred. At one of these (the northern avulsion), Indus water flooded ~8,000 km of agricultural land to depths of 1–3 m; part of the river flowed 50–100 km west of its pre-flood location. The avulsion was caused by breaching of the Tori Bund, an artificial levee upstream of Sukkur Barrage, on 6–7 August, two days before arrival of the first flood crest and long before attainment of peak river flow at Chacharan, 100 km upstream, on 24 August. The early breach, during the rising stages of the flood, permitted much of the incoming flood wave to feed the avulsion over a sustained period. As was the case for the dramatic and temporary avulsion of the Kosi River, India, in 2008, the lack of planned accommodation to the river’s high sediment load and its super-elevation above the surrounding terrain set the stage for exceptionally dangerous levee failures and channel avulsions. Major translocations of river flow will continue to occur during large flood events whether flood warning is improved or not. The observed dynamics indicate that reinforcing the existing engineering structures is not a sustainable strategy for avoiding future flood catastrophes. Instead, planning for major water and sediment flow diversions is required for effective flood control along the Indus and other sediment-rich and avulsion-prone rivers.