Tracking sediment waves through Himalayan fluvial cascades following extreme mass flows

跟踪极端质量流后穿过喜马拉雅河流瀑布的沉积物波

• 批准号: NE/Y002911/1
• 负责人: Matthew Westoby
• 金额: $ 10.87万
• 依托单位: Plymouth University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FY002911%2F1
• 关键词: Tracking; sediment; waves; through; Himalayan

Mountain landscapes experience sudden and violent geohazards, such as landslides, lake outburst floods, and debris flows. The size and frequency of such events is anticipated to increase due to climate change, enhancing landscape instability. These landscapes are also experiencing rapid population growth, directly exposing people and assets to geohazards, but also exposing them to legacy impacts which manifest after an event and are commonly overlooked and unquantified. A legacy impact of many mountain geohazards is enhanced coarse sediment transport in rivers. This is a problem because sediment travelling as 'bedload' is the primary driver of river channel adjustment. These adjustments affect: 1) flood hazard, by modifying channel bed elevation; 2) the integrity of riparian infrastructure, e.g. hydropower, by blocking intakes and rapidly filling reservoirs, and 3) fluvial ecology, by reorganising channel substrate. It is therefore vital to generate well-constrained knowledge of the pace and manner in which the bedload transport regime evolves in mountain rivers after extreme disturbances. However, due to technical limitations and challenges associated with working in unstable, post-flood landscapes, we have little first-hand information on the behaviour of such systems, which this project aims to address.This new project will consolidate a new international partnership of leading researchers from the UK and India. The team is led by the University of Plymouth, working in close collaboration with the Indian Institute of Technology Roorkee (IITR) and the Wadia Institute of Himalayan Geology (WIHG), the University of Exeter, and Newcastle University. The diverse team bring complementary expertise in geomorphology, hydrology, and environmental sensor networks, and the work would not be possible without the regional knowledge, technical competencies, and field experience of the international partners. The project also features prominent early- and early-to-mid-career researchers in leading roles. Working together we will apply a suite of innovative environmental monitoring and modelling tools to characterise the hydrological and bedload transport regime of the Alaknanda river, Uttarakhand, India, which experienced an extreme debris flow in February 2021 which killed >200 people and triggered enhanced sediment transport as a legacy impact, evidenced through pilot work.To achieve our aim, we will: 1) Develop a new hydrological model of the Alaknanda catchment, enabling us to identify and disentangle the key components of flow (e.g. snowmelt, rainfall). This information will be used to better understand the hydrological drivers of sediment transport; 2) Quantify the grain size characteristics of channel bars using drone- and satellite-based observations and modelling. This information will allow us to explore downstream transitions in grain size through time and examine the influence of the Chamoli event; 3) Deploy innovative, low-cost 'smart' tags to track the motion of cobbles and boulders travelling as bedload. We will supplement these data with measurements of the timing and relative magnitude of bedload transport using low-cost passive seismics. We will effect skills and knowledge transfer in-person via joint fieldwork and discussions at IITR and WIHG), and a regular series of virtual project meetings and seminars. We will publish results in peer-reviewed open-access journals and will produce a technical summary report which we will disseminate to local stakeholders. Project success will lead to future joint funding bids which will appraise the role of hydropower as a disruptor to coarse sediment transport in mountain rivers and explore operational practices that can mitigate the immediate and legacy impacts of extreme floods. In doing so we will further consolidate a wider research network involving regional academics and practitioners, whilst supporting the development of early career researchers in both countries.

山地景观经历突发和剧烈的地质灾害，如山体滑坡、湖泊溃决洪水和泥石流。由于气候变化，预计此类事件的规模和频率将增加，从而加剧景观的不稳定性。这些地区的人口也在快速增长，直接使人和资产面临地质灾害，但也使他们面临地质灾害后显现的遗留影响，这些影响通常被忽视和无法量化。许多山地地质灾害的遗留影响增强了河流中的粗沙输运。这是一个问题，因为泥沙作为“河床”移动是河道调整的主要驱动力。这些调整影响：1)通过改变河床高程影响洪涝灾害；2)通过堵塞进水口和快速填满水库来保持河岸基础设施（如水电）的完整性；3)通过重组河道基质来保持河流生态。因此，在极端扰动之后，对山中河流的河床输运机制演变的速度和方式有充分的了解是至关重要的。然而，由于技术限制和在不稳定的洪水后景观中工作所带来的挑战，我们对这种系统的行为几乎没有第一手信息，而这正是本项目旨在解决的问题。这个新项目将巩固来自英国和印度的主要研究人员的新的国际伙伴关系。该团队由普利茅斯大学领导，与印度理工学院（IITR）和喜马拉雅地质Wadia研究所（WIHG），埃克塞特大学和纽卡斯尔大学密切合作。多元化的团队带来了地貌学、水文学和环境传感器网络方面的互补专业知识，如果没有国际合作伙伴的区域知识、技术能力和实地经验，这项工作是不可能完成的。该项目还邀请了杰出的早期和早期至中期职业研究人员担任领导角色。我们将共同努力，应用一套创新的环境监测和建模工具来描述印度北阿坎德邦Alaknanda河的水文和河床运输制度，该河流在2021年2月经历了一场极端的泥石流，造成200多人死亡，并引发了泥沙运输的增强，作为遗留影响，试点工作证明了这一点。为了实现我们的目标，我们将：1)开发一个新的Alaknanda流域水文模型，使我们能够识别和解开流量的关键组成部分（例如融雪，降雨）。这些信息将用于更好地了解泥沙运输的水文驱动因素；2)利用无人机和卫星观测和建模，量化沙洲的粒度特征。这些信息将使我们能够探索粒度随时间的下游转变，并检查Chamoli事件的影响；3)采用创新的、低成本的“智能”标签来跟踪鹅卵石和巨石作为床载物的运动。我们将利用低成本的被动地震对层质运移的时间和相对震级进行测量，以补充这些数据。我们将通过在IITR和WIHG的联合实地考察和讨论，以及一系列定期的虚拟项目会议和研讨会，亲自实现技能和知识的转移。我们将在同行评审的开放获取期刊上发表结果，并将制作一份技术总结报告，我们将向当地利益相关者分发。项目的成功将导致未来的联合融资投标，评估水电作为山地河流粗泥沙运输干扰因素的作用，并探索可以减轻极端洪水的直接影响和遗留影响的操作实践。通过这样做，我们将进一步巩固一个涉及地区学者和实践者的更广泛的研究网络，同时支持两国早期职业研究人员的发展。