MODELLING RAPID LANDSCAPE CHANGE DUE TO OUTBURST FLOODS

对突发洪水导致的快速景观变化进行建模

基本信息

批准号：
NE/F000235/1
负责人：
Jonathan Carrivick
金额：
$ 9.5万
依托单位：
University of Leeds
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FF000235%2F1
关键词：
MODELLING RAPID LANDSCAPE CHANGE DUE

项目摘要

The aim of this project is to model flow-bed interactions within an outburst flood. Outburst floods are a sudden release and advancing wave of water and sediment, with a peak discharge that is often several orders of magnitude greater than perennial flows. Common outburst floods from natural sources (i.e. excluding breaches of man-made dams) include those from glacial and moraine-impounded lakes, freshwater dyke and levee bursts, volcanic debris dams, landslides, avalanches, coastal bay-bars, and those from tree or vegetation dams. Although these hazards sound exotic, outburst flood hazards are regularly incorporated into risk assessments for urban, coastal and mountainous areas, for example. Outburst flood hazards are primarily due to direct impacts, caused by a frontal surge wave, from debris within a flow body, and from the mass and consistency of the flows. A number of secondary impacts also pose hazards, including widespread deposition of sediment and blocked tributary streams. It is rapid landscape change, which is achieved the mobilization and redistribution of sediment that causes one of the greatest hazards due to outburst floods. Thus a particular focus of this project will be to parameterise hydrodynamic and sedimentary characteristics; particularly flow depth, velocity, bed shear stress, energy and power, sediment sorting, grain size distribution and architecture. Hydrodynamic and sedimentary characteristics of outburst flood processes will be obtained using fully parameterised and validated laboratory flume modelling, which offers a hitherto untapped opportunity for examining complex interactions between water and sediment within outburst floods. Explicit quantification of water-sediment processes within outburst floods is essential for several reasons: 1. Outburst floods occur worldwide and are a natural hazard to life, property and infrastructure. 2. Although all outburst floods are a mix of water and sediment, models that fully integrate both processes are unreported. 3. Whilst sources of outburst floods and trigger mechanisms are well known, flow behaviour is not, largely because of the inherent problem of directly measuring such sudden, powerful and rapidly-varying flows. Prediction of flow character is therefore currently very limited. 3. Outburst flood mitigation measures can only be produced when processes governing flow behaviour are well understood; i.e. parameterised and modelled, and that model is validated against real-world data. These criteria must arise from an integrated and sustainable design approach. 4. With climate change, there is a very real potential for alterations in air temperature and precipitation patterns to cause an increased frequency of glacial lake outbursts and landslide-triggered outbursts, and an increased magnitude of rainfall-induced outburst floods. 5. Most outburst floods are sourced from natural lakes that are otherwise a water resource, and with appropriate management solutions can remain so. This project is extremely timely because recent outburst floods from Sólheimajökull (Iceland) and the predicted Crater Lake flood from Mt Ruapehu (New Zealand) are constrained with precise pre- and post-event surveys that provide hitherto unobtainable data for model parameterisation and validation. The latter will also be characterised by a state-of-the-art sensor system under development by GNS Science and Massey University to yield time-series data on flow behaviour and hydraulic parameters. This project will clearly be a substantial contribution to NERCs mission by providing quantitative data to advance knowledge and support for natural hazard solutions, which will be of economic and social benefit to industry and to the public sector, and by engaging excellent researchers from several disciplines and countries.

该项目的目的是模拟突发洪水内的流床相互作用。突发洪水是水和沉积物的突然释放和推进，其峰值流量通常比常年突发洪水大几个数量级。来自自然资源的水（即不包括人造水坝的溃决）包括来自冰川和冰碛蓄水湖、淡水堤坝和堤坝决口、火山碎片水坝、山体滑坡、雪崩、沿海湾坝以及树木或植被坝造成的灾害虽然听起来很奇怪，但突发洪水灾害经常被纳入城市、沿海和山区的风险评估中。由锋面涌浪、流体内的碎片以及水流的质量和稠度引起的直接影响也会造成危害，包括沉积物的广泛沉积和支流的堵塞。快速的景观变化，导致沉积物的流动和重新分布，从而导致突发洪水造成的最大危险之一，因此该项目的一个特别重点是参数化水动力和沉积特征，特别是水流深度、速度、河床剪切力；突洪过程的应力、能量和电力、沉积物分类、粒度分布和结构将通过完全参数化和经过验证的实验室水槽模型获得，这为研究提供了迄今为止尚未开发的机会。出于以下几个原因，研究突发洪水中水和沉积物之间的复杂相互作用至关重要： 1. 突发洪水在世界范围内发生，对生命、财产和基础设施构成自然危害。洪水是水和沉积物的混合体，但完全整合这两个过程的模型尚未报道。 3. 虽然突发洪水的来源和触发机制众所周知，但水流行为却并非众所周知，这主要是因为其固有的原因。因此，直接测量这种突然的、强大的和快速变化的水流特征的预测目前非常有限。 3. 只有在充分了解控制水流行为的过程（即参数化和建模）后才能制定防洪措施。模型必须根据现实世界的数据进行验证。4.随着气候变化，气温和降水模式的变化确实有可能导致冰川湖溃决频率增加。滑坡引发的洪水，以及降雨引发的洪水泛滥的情况。 5. 大多数洪水源自天然湖泊，而这些湖泊本来就是水资源，而且通过适当的管理解决方案，该项目非常及时，因为它是最近才实施的。索尔黑马冰川（冰岛）爆发的洪水和鲁阿佩胡山（新西兰）预测的火山口湖洪水受到事件前和事件后精确调查的限制，这些调查提供了后者还将由 GNS Science 和梅西大学正在开发的最先进的传感器系统来表征，以产生有关流动行为和水力参数的时间序列数据。通过提供定量数据来推进自然灾害解决方案的知识和支持，这将为工业和公共部门带来经济和社会效益，并通过吸引来自多个学科和国家的优秀研究人员，这显然是对 NERC 使命的重大贡献。