The School of Geography, Politics and Sociology

Staff Profile

Dr Stuart Dunning

Senior Lecturer in Physical Geography

Background

Interests

Keywords: Landslides; magnitude-frequency; paraglacial; geomorphology

I am a quantitative physical geographer researching hillslope processes and their magnitude-frequency, often in cryospheric systems undergoing rapid change. I have a speciality in large rock-avalanches, with a focus on their dispersion through glacial and fluvial reworking which serves to reduce our knowledge of their erosive work, and, to underestimate their hazard.














Research

Current Projects

1. Landslides triggered by Storm Desmond at the A83, Rest and Be Thankful, Scotland (NERC Urgency, £47k); Innovative monitoring strategies for managing hazardous slopes (Scottish Roads Research Board, £72k)

NERC URGENCY: Storm Desmond produced intense and prolonged rainfall which resulted in extensive flooding in the U.K. A number of landslides were also triggered, many of which damaged infrastructure and the transport network in particular. We are in a unique position, holding pre-event, and during event data for slopes that failed during and after Storm Desmond  at the most 'at risk' trunk road in Scotland1-3, the A83 Rest and Be Thankful (RABT), Argyll and Bute, which is a key arterial route. Since 2007 at least 13 debris flows have occurred. Existing monitoring has been invaluable in defining post-event conditions and sediment dynamics with instruments often installed after events, but there are no complete (pre- and post-) data on a single large event. This is essential in refining and validating physical and numerical modelling approaches, which can be used for enhanced management of the problem, and the design/refinement of appropriate monitoring and mitigation strategies that our project partners are responsible for putting into operation. Our proposal is to collect transient post-event data to allow follow-on funding proposals to answer the outstanding science questions, which are relevant for multiple sites beyond the RABT, and to document the transience of key evidence to inform how 'urgently' we do need respond to future large events to adequately quantify them.

SRRB: Building on existing infrastructure and knowledge at the A83 Rest and Be Thankful we wish to implement a novel multi-level modular monitoring system to detect landslide activity prior to, during and after landslide events. The aim is to produce a business case for appropriate monitoring to enable cost-effective management of hazardous slopes in Scotland. 

Rest and Be Thankful A83 site

2. Landslides onto and into glaciers (Funded PhD Student William Smith)

Slope processes play a significant role in sediment delivery to ice; a role of increasing importance as landscapes transition between glacierised and ice-free configurations. Landslide magnitude-frequency (m-f) which dictates the erosion of land exposed above ice surfaces (landslides, not glaciers, reduce peak height above ice) and the resultant sediment flux through the glacier-route-way is poorly quantified, particularly when the debris is entrained and transported en- and sub-glacially and  re-emerges (altered or unaltered) in the ablation zones. Crucially, we have been unable to elucidate climate change-driven perturbations in m-f due to the sparsity and incompleteness of existing datasets and the absence of a thorough analysis of the suite of relevant environmental drivers. Estimates of the flux from landslides onto ice range from just a few percent to 60% of total glacial sediment flux.

We hypothesise that landslides in the Arctic and Antarctic deliver significant quantities of sediment including bioavailable iron (BioFe), silica, and nitrogen to the Oceans. 

Spot the rock avalanche deposit

3.  Finding tsunami causing landslide deposits in the lakes of New Zealand (NERC IAPETUS Student Ryan Dick)

Relief in mountainous landscapes is a balance between the forces of tectonics, climate, and surface processes. Landslides are an effective means of limiting the growth of mountains to maintain some form of equilibrium, with seismic shaking in particular able to trigger widespread failure and downslope mobilisation of material. It is common that during earthquakes a number of very large, highly mobile landslides, termed rock avalanches, can be expected to be triggered from steep mountainsides with sufficient relief. If rock avalanche run out paths reach settlements or infrastructure, destruction is almost total and with death tolls historically measured in thousands. However, in many of the landscapes where these events happen, the rates of geomorphic processes are high enough to erode and remove most evidence of past events. As a result, the relative frequency of these catastrophic events remains poorly understood, and so the risks posed remains poorly understood.
Advantageously, in previously glaciated terrain deep fiords and inland lakes are common, and interestingly, provide a unique geomorphic setting that can capture the record of past large landslides through underwater preservation of the landslide deposits. If these landslide deposit post-date initial lake formation / relative sea level rise, they may also have triggered tsunami, which themselves pose further risks to a wider area.

4. A new approach to West Antarctic Ice Sheet evolution using blue-ice moraines on nunataks.

Did the West Antarctic Ice Sheet (WAIS) survive the last interglacial? We propose to use nunataks as dipsticks of ice-sheet elevation change to help answer this question. There are currently two conflicting hypotheses:  

Hypothesis 1: A dynamic WAIS. The hypothesis is that the WAIS disappeared under last-interglacial conditions ~125,000 years ago when climatic and oceanic conditions were slightly warmer than those of the present day.

Hypothesis 2: A stable WAIS. The WAIS may have varied in elevation but that it persisted as a coherent ice sheet during the last interglacial.  

The co-existence of two opposing hypotheses implies that we have much to learn about the principal controls on ice-sheet stability. This uncertainty undermines confidence in our ability to predict the future of the WAIS and its effect on global sea-level change. Important research on the WAIS relies on satellite observations which monitor changes in velocity and elevation over recent decades, while predictions of future changes rely on ice-sheet models. Both approaches would be enhanced if we knew what happened to the WAIS during the last glacial cycle. The longer term perspective tells of the trajectory of change upon which decadal changes are superimposed. Further, a history of elevation changes during a glacial cycle provides data with which to constrain and improve ice-sheet models.  

This project is testing the two hypotheses using moraines that form on nunataks in blue-ice areas. Blue-ice areas result from strong downslope winds which are often funnelled in the vicinity of nunataks and ablate the ice surface. In response the ice flows into such ablation areas, sometimes bringing basal debris to the surface which is then deposited at the ice margin. Relict moraines occur on certain nunatak slopes above the present ice surfaces and are over 400,000 years old, suggesting that there is the potential to obtain a long record of ice elevation change.  

This project brings together glaciologists, geomorphologists and geophysicists to work in the Heritage Range, a group of nunataks which protrude through the central WAIS dome. We will test predictions of the two competing hypotheses firstly by examining the processes of blue-ice moraine formation today using field survey and radar, and secondly by establishing the form and sediment characteristics of the moraines and their age. The latter will employ exposure-age dating, a technique that measures the time a rock has been at the surface and exposed to cosmic rays. By using more than one isotope we can establish times when a rock surface may have been buried by ice and thus there is the potential to reconstruct a rich history of ice elevation changes. In this way we will assess if the WAIS remained intact, or disappeared during the last interglacial. Our hope is that the approach could be extended to other nunataks in Antarctica and provide widely dispersed evidence of elevation changes in predicting the future response of the WAIS to a changing climate.

NERC Standard Grant (February 2012 – July 2015). Sugden, D., Woodward, J., Dunning, S., Fogwill, C. £557,733.00 (Northumbria £148,480.34) NE/I025840/1

Publications