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.

山地景观经常遭受突然而猛烈的地质灾害，如山体滑坡、溃决洪水、泥石流等。由于气候变化，此类事件的规模和频率预计会增加，从而加剧景观的不稳定性。这些景观也正在经历快速的人口增长，直接使人员和资产面临地质灾害，但也使他们受到遗留影响，这些影响在事件发生后显现出来，并且通常被忽视和未量化。许多山区地质灾害的遗留影响是增强了河流中粗沉积物的输送。这是一个问题，因为沉积物作为“床质”移动是河道调整的主要驱动力。这些调整会影响：1）通过修改河床高程来消除洪水灾害； 2) 河岸基础设施的完整性，例如水力发电，通过阻塞进水口和快速填充水库；3）河流生态，通过重组河道基质。因此，对山区河流在极端扰动后底质输送状况演变的速度和方式进行严格的了解至关重要。然而，由于技术限制和与在不稳定的洪水后景观中工作相关的挑战，我们对此类系统行为的第一手信息很少，而本项目旨在解决这一问题。这个新项目将巩固新的国际伙伴关系来自英国和印度的顶尖研究人员。该团队由普利茅斯大学领导，与印度鲁尔基理工学院 (IITR) 和瓦迪亚喜马拉雅地质研究所 (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、技术能力和现场经验，这项工作就不可能完成。该项目还邀请了杰出的早期和早期到中期职业研究人员担任领导角色。我们将共同合作，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 河的水文和底质输送状况，该河流于 2021 年 2 月经历了一场极端泥石流，导致超过 200 人死亡，并引发了沉积物输送加剧作为遗产影响，通过试点工作得到证明。为了实现我们的目标，我们将： 1) 开发阿拉克南达流域的新水文模型，使我们能够识别和理清水流的关键组成部分（例如融雪、降雨）。这些信息将用于更好地了解泥沙输送的水文驱动因素； 2) 使用无人机和卫星观测和建模来量化槽钢的晶粒尺寸特征。这些信息将使我们能够探索下游颗粒尺寸随时间的变化，并检查查莫利事件的影响； 3) 部署创新、低成本的“智能”标签来跟踪作为垫料移动的鹅卵石和巨石的运动。我们将使用低成本被动地震测量床土输送的时间和相对强度来补充这些数据。我们将通过 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，亲自进行技能和知识转移。我们将在同行评审的开放获取期刊上发表结果，并将编写一份技术摘要报告，并将其分发给当地利益相关者。项目的成功将导致未来的联合资助投标，该投标将评估水电作为山区河流粗泥沙输送干扰者的作用，并探索可减轻极端洪水的直接和遗留影响的运营实践。在此过程中，我们将进一步巩固涉及区域学者和从业人员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。