Reading the rocks: how we can predict landslides to keep homes safe and highways open

Anna Rose: Thanks for downloading Life Solved from the University of Portsmouth. This is the series where we hear how world-changing research is taking place here today to shape our tomorrow. Last time, we heard how satellite imaging and crowdsource data can help scientists and authorities prepare and respond better to disasters. And today, we're hearing from a Portsmouth researcher who's applying his science to support incredible feats of engineering.

Malcolm Whitworth: Geomorphology is a term we use basically for trying to understand what the ground is like, what impact the ground condition might have on an engineering project.

Anna Rose: Malcolm Whitworth is a reader in engineering, geomorphology and natural hazards.

Anna Rose: Malcolm is a true applied scientist. He does both research and commercial work, advising companies on ground conditions and potential issues to help them plan their investigations ahead of a construction project. That might be on transport construction and maintenance or vital resource pipelines. Either way, it's pretty essential to keep these connections open and operating safely. His main work can cover structures that extend for thousands of miles. He explained this to John Worsey.

Malcolm Whitworth: So my work is mainly on what we term sort of linear infrastructure. So roads, railways, pipelines. Very long, thin features which mean they go across lots of variable geologies. If you find it early on, it saves a vast amount of money later.

Anna Rose: So preventing literal geological roadblocks in some cases can save developers spending their resources on working around a problem, re-planning or recovering their projects if say, a landslide occurs. But how can you predict such an event? We'll find out. Malcolm was passionate about geology from a young age, but his interest in new technology combined with this when he started using satellite data to predict hazards.

Malcolm Whitworth: Historically, it was always done via using photographs and walk over. So you go out of sight, you walk over. So you might spend a huge amount of time walking these areas. And that's where my kind of interest lies in applying these new technologies to understand the ground better and to try to predict what the hazards might be.

Malcolm Whitworth: The natural hazards are, I suppose, something that a natural process that has the potential to cause harm.

John Worsey: Yeah.

Malcolm Whitworth: So that can be harm to people or could be damage to infrastructure or communities or the environment. So the kinds of things we're talking about are, obviously, things like big volcanic eruptions, earthquakes and ground shaking, big landslides – and by that, we mean will the slope fails and the material then comes down and that can have a big impact. It can be flooding, obviously, is a major hazard in the UK, has a major impact on communities. Those are the kind of things that we're talking about. So my interest is really around the slope stability and the landslide side. But I do some other hazards and so on.

Anna Rose: A typical impact report for Malcolm assesses what kind of hazard is present, how frequent and strong it is, and what the impact might be upon nearby communities and infrastructure like roads. From that, local authorities can make decisions on how to avoid or minimise creating these hazards.

Malcolm Whitworth: I've done a lot of work in the UK for companies looking at hazards in the UK, slope stability, but also more generally in terms of risks to roads and pipelines from different types of hazards. So that spans things like landslides, through to flooding, through to what we term problematic ground. I've done focus work on landslides in Georgia, Kyrgyzstan, and I'm currently working in Tajikistan. And I've also just come back from China, where we're working with some Chinese colleagues on also looking at the big highway construction. They've got this, you know, big highway construction going on. What's important in my role is ensuring that we have a good understanding of the hazards, but also their impact on communities and making sure that we reduce the impact of these hazards on communities. That's what I want to do, is make sure that all my work has a real human impact, i.e. reduction in fatalities and a sort of improvement in quality of life for those people who are living in areas that are subject to quite significant hazards.

John Worsey: Yeah. So the primary thing for you is people's safety and people's quality of life.

Malcolm Whitworth: Yeah. Exactly. And obviously, things like, for example, if a road is cut off, that has a major impact on trade, communication, etc. So it's all those additional factors that affect quality of life. So making sure that it's not people are hurt or killed, we don't want that, obviously. It's also making sure that towns aren't affected, and roads and stuff aren't affected. And so those routes are available for them to use.

Anna Rose: Malcolm's current work is focused on one of the most important trade routes in the world, the enormous Pamir Highway, or M-41. But this highway is subject to major hazards as it stretches across often mountainous terrain, as it winds its way across Afghanistan, Uzbekistan, Tajikistan and Kirgizstan. It regularly suffers from erosion, earthquakes, landslides and even avalanches. And yet provides a vital international trade route along the former Silk Road. A pretty beautiful and inspiring place to work so closely with the landscape. Satellite data is crucial to understanding such a long stretch of terrain, though, and there's a good reason Malcolm favours this kind of observation rather than drones on this scale.

Malcolm Whitworth: Drones have been used, but in Tajikistan, they're very sensitive about drones. You're not allowed drone flights. We have used drones to look at hazards in a lot of detail. We've done work in Iceland, looking at active tectonics. We've done work in the UK looking at some land sliding and landslide monitoring. So they can be used but because the area we're talking about is 11,000 square kilometres, so it's a very large area. So it's the second-highest altitude highway in the world. And it does link the two main administrative regions but also links most of the countries to China. It also links Kyrgyzstan, Uzbekistan, Tajikistan together. So it's a really, really important highway. And it's the only major road that goes through those mountains.

John Worsey: And historical, right? Because it was part of the Silk Road originally. So it's always been a really important trade route.

Malcolm Whitworth: I think it still remains that. Yeah. So it's quite... And also, was built during the 30s by the Russians, but also is now part of a European highway as well. So the Europeans now consider it part of some of the sort of international links as well. So it is an incredibly important trade route between those countries. But unfortunately, it's affected by landslides, earthquakes on a regular basis. So it is a real problem. Because often a landslide goes across the road, you can't pass the landslide and you've got a huge amount of material to remove. It can block the road and delay for days.

John Worsey: What is it about that area then that makes it so prone to landslides?

Malcolm Whitworth: Well, basically, the fundamental thing is it is a mountain range. You've got very steep slopes. You've got lots of erosion. Weak geology. You've also got earthquakes, which when you shake the ground, then you meet the ground, the ground can fail, obviously, if you shake it. You've also got river erosion as well. So you've got all the-- all the factors that would contribute to a failure. But the main one is the fact it's just such a steep mountainous terrain.

Anna Rose: It's natural for landslides and erosion to take place on mountains. But how do you go about managing that?

Malcolm Whitworth: Definitely yearly basis, following sort of the spring period, the road will come to a halt until they get teams out to clear it. So it's on a regular basis. It also depends on which part of the road you're looking at as well. So some are more mountains than others and are more susceptible to slope failures.

Anna Rose: A small team of students work on behalf of the design firm Arup and the World Bank on a three-stage project, the first part of which is mapping.

Malcolm Whitworth: Using some imagery provided to us by the European Space Agency.

John Worsey: Right. So satellite?

Malcolm Whitworth: Satellite imagery. Yeah. So really very high-quality data, and we're using that to look at the landscape and identify landslides from the imagery. We're also using other datasets as well to corroborate that. But, essentially, we're producing what's termed an inventory, which is basically a map that shows where all the landslides are. And then we're trying to identify the type. Are they big or have the size?

John Worsey: Yeah.

Malcolm Whitworth: But also trying to understand how often they occur. So we're kind of looking back in time to see how old that landslide is, to see how frequently occur. So if we can see they're occurring every five years or every 10 years, we get an idea about the kind of what we tend to recurrence interval is of that problem, and that helps us to understand the impact on the road. So then, once you've done that, we are then looking at the road. So what's the vulnerability of the road, the standard of the road, the maintenance of it, etc. Where it has been affected by landslides before, and then what we're doing is we're producing a combined risk, which is where we say, OK, given these landslides in these areas, what is the impact on the road? How long will the road be closed, etc.? That helps the community understand if that's close, what the impact will be financially and etc on the communities. You could prevent that from happening by maybe these simple measures. Maybe in those areas that are of the highest problem, they could put in some simple mitigation that might prevent the road being completely blocked.

John Worsey: Yeah.

Malcolm Whitworth: And therefore, meaning the road stays open longer.

Anna Rose: So mapping helps make informed predictions about the scale, frequency and community impact of a landslide, both in terms of human safety, access and economy. Looking ahead like this helps developers avoid problem spots, and in some cases, keep roads open. That means authorities and developers can focus resources in the most important places or build preventative structures.

Malcolm Whitworth: You provide essentially a map which says, there's your road. We've done our work and we think that these particular sections are the ones that we think are going to be most problematic.

Anna Rose: But this is only one part of the equation. The evaluation and modelling stages then take into account other environmental factors and piece the data together to make predictions.

Malcolm Whitworth: Really things like geology, rainfall, groundwater, river and erosion. We put all that data together and then we take the landslide mapping we've done, we combine them together and that tells us about, OK, that area is very prone because you get a lot of rainfall and you've got this weak geology and you've got very steep slopes. So once we know that's a precursor, we go, oh, that area over there is pretty similar. Even though we may not have had the landslides, what we say is because it has got similar precursory conditions, we say that may also be susceptible. So we use that as a sort of a predictive tool to identify areas that may be affected. We also do modelling whereby, particularly for debris flows, we found very long ones. So these things will start in a mountain but will flow for several kilometres down before it gets to the road. So. So those are really difficult because those are not ones that we would necessarily predict. They start and they just keep moving for such a long time.

John Worsey: And presumably the further it goes, the harder it is to know where it's going to hit.

Malcolm Whitworth: Absolutely. The thing it's what's termed bulky. So as it's going down,