Project aims to forecast long-term effects of debris transported by natural disasters

University of Plymouth

 

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The confluence of the Alaknanda and Bhagirathi Rivers, which represents the source of the Ganges. Differences in the colour of the water are the result of variations in sediment load, which can be caused by landscape disturbances originating higher in the catchment

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Credit: Matt Westoby/University of Plymouth

Landslides, avalanches and glacial floods can have an immediate and devastating effect on anything in their path. However, a £1million research project is now going to explore their potential to impact communities often located hundreds of kilometres away and many years after an event has originally taken place.

Centred on the headwaters of the Ganges River in the Himalayas, the SUPERSLUG initiative is named after the huge masses of debris created by such natural disasters, sometimes described as sediment slugs when they travel down rivers.

Using a range of novel monitoring technologies and sensors, scientists will develop and test numerical models to provide the most comprehensive predictions yet of where, when and how the long-term impacts of recent and future extreme events might be felt.

The three-year project is being supported with a grant of almost £840,000 from the Natural Environment Research Council, part of UK Research and Innovation.

Led by researchers from the University of Plymouth, with colleagues from the universities of Exeter, Hull, Leeds, Newcastle and Staffordshire, the project will also harness the expertise of academics at the University of Calgary, Indian Institute of Technology Roorkee and the Wadia Institute of Himalayan Geology.

Dr Matt Westoby, Associate Professor of Physical Geography at the University of Plymouth, is the project’s lead. He said: “High mountain regions such as the Himalayas and the Andes are among the most active – and most hazardous – on the planet. The effects of a changing global climate are only going to exacerbate that hazard, with more intense monsoons leading to increased landslide activity, and the retreat of glacial ice cover causing landscape instability and triggering far-reaching floods.

“But while the immediate effects of those events might be felt locally over the space of a few hours, the large volumes of sediment they generate could impact the river systems for a decade and more. We currently know very little about these longer-term legacy impacts, which can be more insidious and reveal themselves after the main source of danger has passed. We urgently need to understand their effects on river catchments and the communities that rely on them for water, power and their livelihoods more generally.”

The project will focus on a 150 km stretch of the Ganges River impacted by the 2021 Chamoli disaster. Initially triggered by a rock and ice avalanche, a fast-moving, debris-laden flood killed more than 200 people with extensive and severe damage being caused across the region, including to valuable hydropower and transport infrastructure.

In the immediate aftermath, scientists from across the world – including many of those involved in the SUPERSLUG project – came together to understand the processes that led to the initial disaster. 

Over the last two years, funding from UK Research and Innovation enabled pilot work in collaboration with in-country partners to better understand the short-term legacy of the disaster, pump-priming the more ambitious SUPERSLUG project.

The new research will use the data gathered during that time, as well as using drones and satellite imagery to monitor changes in the landscape and river system over the space of several years.

It will also employ seismic sensors and wireless ‘smart cobbles’ alongside other complementary techniques, including automatic water level monitoring, to explore how sediment is transported during normal and flood conditions.

This and other information will be used to develop a large-scale digital twin of the river system, which will be used to explore catchment management decisions.

Importantly, the project team will engage directly with communities and authorities in the Ganges region, to ensure their findings are accessible and useful to disaster management professionals, hydropower operators and the wider international academic community.

Professor Tom Coulthard, Professor of Physical Geography at the University of Hull, is also part of the team coordinating the SUPERSLUG project. He said: “Often it’s the rocks, house sized boulders and sheer volume of sediment moved rather than flood water that causes the most damage in these cascading multi-hazard events. It’s thought this mass of sediment released downstream could pass through the system like a wave or slug of sediment, but how long it takes for this slug to move on through is largely unknown. It may be years, decades or centuries – so understanding how long a sediment slug sticks around for is fundamental for managing these events and predicting their impacts.”