Physical geography example PhD topics

Glacier ‘collapse feature’ formation: mechanisms and significance in relation to glacier retreat

Lead supervisor: Dr Darrel Swift

Other supervision team members: Dr Robert Bryant

Project description:

Circular ‘collapse features’ (or funnel-like depressions) characterised by ring-like concentric crevasse formation around a subsiding central zone of ice have been observed on temperate Alpine glaciers for nearly a century but recent observations indicate their increasing presence and possible significance for rapid terminus disintegration and retreat. Few detailed studies of collapse feature formation have been undertaken, meaning the precise context and timing of formation during ongoing glacier retreat remains poorly known. Even fewer studies have collected field-based observational data on rates and sources/processes of collapse, including hydrological measurements required to constrain localised drainage system morphology. This project would combine longitudinal analysis of collapse feature formation acquired using remote sensing approaches with information on glacier mass balance change and bed topography as well as field-based measurements of glacier and collapse feature characteristics to improve knowledge of their context, evolution and mechanisms. At the same time, these observations will provide important insight into the relationship between collapse feature formation and rapid mass loss from mountain glacier systems in the Alps.

For further information, please contact Darrel Swift (d.a.swift@sheffield.ac.uk).

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Projecting the mass balance of glaciers in Alaska

Main supervisor: Dr Jeremy Ely

Other supervision team members: Dr Julie Jones, Dr Sihan Li

Project description:

Glaciers are sensitive barometers of climate, growing and shrinking as climate changes. The size of glaciers and the amount of mass they store is determined by a balance of inputs such as snowfall and outputs such as melting. Like a bank balance, the mass balance of glaciers decreases if snowfall goes down or melting increases. In our warming world, snowfall patterns are changing, and rising temperatures are increasing levels of melt. Unfortunately, this is causing glaciers to go into their overdraft, with the vast majority losing stores of ice due to their negative mass balance. The additional melt is spent on rising sea levels, as the water that should be stored in glaciers reaches the oceans. For several decades, the biggest spenders have been Alaskan glaciers; a spree which many predict is set to continue. However, projections of future glacier mass balance are currently highly uncertain, presenting a challenge when planning for future sea level rise. In this project, we will explore means for improving the projections of glacier change. To achieve this, we will combine state of the art climate, energy balance and ice-flow models, and explore data assimilation techniques. 

For further information, please contact Jeremy Ely (j.ely@sheffield.ac.uk).

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The final fling of glaciation in Britain and Ireland

Main supervisor: Dr Jeremy Ely

Other supervision team members: Professor Chris Clark

Project description:

Approximately 30 thousand years ago, an ice sheet grew over Britain. It reached its maximum extent a few thousand years later, at which point an ice sheet which was several kilometres thick covered most of the British Isles and the surrounding sea floor. But, as the last glacial ended, the warmer climate and ocean caused the ice sheet to shrink. Getting rid of the ice sheet took several thousand years, but before ice completely disappeared, cold conditions returned to Britain and Ireland. At this point, glaciation had its final fling, causing the growth of several ice caps, including a large one which engulfed the highlands of Scotland. These ice caps likely resembled those which exist in places such as Iceland today, and therefore studying their dynamic may improve our understanding of how such systems operate. In this project, we will use numerical models to simulate the flow of ice during the final fling of glaciation in Britain and Ireland. We will use these simulations to test the sensitivity of these now extinct glaciers to past rapid climate change, perhaps elucidating how many glaciers will respond to our warming world. 

For further information, please contact Jeremy Ely (j.ely@sheffield.ac.uk).

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The Dynamics of Basaltic Volcanism

Lead supervisor: Dr Tom Pering

Other supervision team members: Dr Thomas Wilkes

Project description:

Basaltic volcanism is one of the most spectacular forms of volcanic activity on this planet, these gas-rich magmas can produce a range of activity styles at the surface, such as quiescent gas release and strombolian explosions. However, basaltic eruption mechanisms are not yet fully understood. There are multiple ways we can investigate these in more detail, including the use of gas monitoring techniques, such as the ultraviolet camera which measures sulphur dioxide and produces high temporal resolution data. We can also use analogue laboratory experiments to understand how gas flows at depth before reaching the surface. A project at Sheffield could focus on one of these areas alone or look to combine to make rigorous links between measurements and hypothesised models of activity.

For further information, please contact Tom Pering (t.pering@sheffield.ac.uk).

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Wind Power Potential in a Changing Climate

Lead supervisor: Dr Sihan Li

Other supervision team members: Dr Julie Jones

Project description:

To meet climate mitigation targets, power systems are having to rapidly change from relying on fossil fuels to renewables such as wind, and investment in wind power has become part of many countries’ strategies to meet emission reduction goals. Weather and climate variability and the possible effects of climate change are likely to change availability of wind resources for power generation, and these effects will be felt differently across the world.

One phenomenon worth considering when assessing the reliability of wind energy is wind-drought: periods of low wind, which have been observed in recent years. Previous studies have suggested that warming is likely to dampen winds in the Northern Hemisphere, whereas the impact in the South Hemisphere is the opposite. However these results are based on climate models with low spatial resolution, which makes it difficult to assess the usefulness of such conclusions.

In this project, we will use a combination of observational records and high-resolution models (on the order of several km), to investigate the past trends and future projections of wind resource availability, with a special focus on wind-droughts, and to explore the implications of such events on wind power potential in this century. We will also explore the physical mechanisms causing the changing wind patterns and wind-drought events.

For further information, please contact Sihan Li (sihan.li@sheffield.ac.uk).

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Long-term evolution of pebble beaches and their resilience to change

Lead supervisor: Professor Mark Bateman

Other supervision team members: TBC

Project description:

Imagine hearing the story of a beach pebble, the storm that brought it there and how long the beach has sat protecting its hinterland. Innovative new luminescence research is opening up the possibility of finding the age of pebble deposition for the first time. Why worry? Climate change is causing sea-level rise, more storminess and higher coastal erosion rates whilst coastal populations and infrastructure are increasing. 2013/14 saw UK coastal storms causing widespread flooding costing over £250 million. Dating old storm deposits and raised beaches would allow better understanding of longer-term sea level changes and the return periodicity and impact of past storm events.  This would allow key stakeholders to better mitigate this risk and protect the coastal environment.

This research will develop a proof of concept to luminescence date beach pebble deposition in order to better understand long-term beach evolution, sea-level changes and storm impacts.

For further information, please contact Mark Bateman (m.d.bateman@sheffield.ac.uk).

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Erosion by the Greenland ice sheet

Lead supervisor: Dr Darrel Swift

Other supervision team members: Dr Stephen Livingstone, Dr Jeremy Ely

Project description:

Ice sheets and their outlet glaciers are responsible for carving spectacular bedrock topography including overdeepened troughs that discharge ice to the oceans. Erosion beneath large ice sheets is also important because the weathering of fine erosion products produced within and evacuated from subglacial areas play an important role in long-term global carbon cycling. The rates of erosion beneath ice sheets and the controlling factors are, nonetheless, poorly known. This study would explore means of quantifying sediment export from areas of the Greenland ice sheet that can be used to tune glacial erosion models that permit exploration of the significance of key controlling factors, including sliding speed and hydrology. Potential approaches to quantifying sediment volumes span both remote sensing and field-based methods, from large-scale analysis of coastal progradation and suspended sediment export, to in-situ monitoring of suspended- and bed-load transport rates close to glacier margins.

For further information, please contact Darrel Swift (d.a.swift@sheffield.ac.uk).

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Holocene glacier extent in the European Alps and implications for landscape evolution

Lead supervisor: Dr Darrel Swift

Other supervision team members: Dr Sihan Li, Dr Julie Jones, Dr Jeremy Ely

Project description:

Patterns of glacial erosion in tectonically active mountain regions are important for setting the base level for above glacier slopes and therefore play an important role in landscape evolution. For example, cirque floor elevation across many mountain regions has been observed to correlate with mean and maximum topographic elevation, indicating that cirque-floor base-level (and therefore cirque-style glaciation) plays a central role in the operation of the ‘buzzsaw effect’, where glaciation appears to set maximum limits on mountain range height. However, interglacial extent of Alpine glaciers remains poorly known. Notably, Holocene glaciers may have been largely confined to cirque basins; however, it is also possible that glaciers extended beyond cirque lips and into deeper valleys below for long periods of time. The latter situation would fundamentally change the spatial pattern and speed of glacial erosion in the landscape, with likely significant implications for mountain landscape evolution. This project intends to use numerical glacier models driven by Holocene climate reconstructions to explore both glacier extent variation and, through implementation of simple glacial erosion laws in these models, the possible implications for rates and patterns of glacial erosion and associated mountain landscape evolution.

For further information, please contact Darrel Swift (d.a.swift@sheffield.ac.uk).

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Glacier Lake Outburst Flood Hazards in a Changing Climate

Lead supervisor: Dr Sihan Li

Other supervision team members: Dr Jeremy Ely

Project description:

Glacier-related floods, especially floods from lake outbursts (GLOFs), are among the most impactful and far-reaching glacier hazards, affecting regions tens to hundreds of kilometres downstream and causing damage to human settlements as well as infrastructure. This type of hazard has been documented over various mountain ranges worldwide. Climate change may aggravate the situation, with continued warming leading to increased melting, further degradation of permafrost, as well as melting of ice buried in lake dams, increasing the threat to human society and the built environment. However, the past trends and projected future change of GLOFs remain poorly quantified, which makes it challenging to assess the risks posed by GLOFs and to implement risk reduction and hazard mitigation measures. In this project, we will use a combination of observations and numerical models (climate→glacier→ hydrological), to understand past GLOFs and to inform better projections of future GLOFs, with a focus on high mountain areas.

For further information, please contact Dr Sihan Li (sihan.li@sheffield.ac.uk).

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Drainage system sensitivity of Alpline glaciers

Lead supervisor: Dr Darrel Swift

Other supervision team members: Dr Rob Storrar (Sheffield Hallam University), Dr Rob Bryant, and members of the SHARDS team (led by Storrar)

Project description:

Seasonal evolution of melt volumes and sources at Alpine glaciers has been observed to drive evolution of en- and sub-glacial drainage system morphology and consequently ice dynamic response to melt input changes, including ice flow ‘speed-up’ behaviour in spring and possibly late-summer situations that reflect routing of melt through contrasting subglacial drainage system morphologies. In addition, undulations in bed topography are thought to affect drainage system and ice dynamic sensitivity to melt volume evolution that could modulate overall glacier response to longer-term trends in warming. This project would use latest-generation UAV (unmanned autonomous aerial vehicle) platforms to explore ice dynamic responses to melt variability at high spatial and temporal resolution to enhance understanding of the influence of drainage morphology and on basal slip patterns and processes and assess the overall implications for future changes in glacier flow.

For further information, please contact Darrel Swift (d.a.swift@sheffield.ac.uk).

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Historical storminess in the North Sea

Lead supervisor: Professor Mark Bateman

Other supervision team members: TBC

Project description:

Knowing the long-term variability of storm tracks, as well as the return period of severe storms is critical for present coastal management, particularly given future rising sea-levels and that winter cyclone activity is projected to increase in the future in the North Sea region.  The return period for the major 1953 storm was thought to be ~50 years but may be less in the future. Whilst advances in hydrological modelling have been made to better predict peak storm-tide height along coastlines refinement requires better understanding of beach parameters and other coastal zone factors.  To achieve this also requires an understanding of how coastlines have responded to change over millennial time-scales.

This research will take a unique approach in combining documentary evidence (including ships logs), newly available climate reanalysis approaches, and sediment dune archive data using novel portable luminescence dating to investigate past storm events in the North Sea.

For further information, please contact Mark Bateman (m.d.bateman@sheffield.ac.uk).

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Arsenic in the food chain

Lead supervisor: Dr Manoj Menon

Other supervision team members: TBC

Project description:

Arsenic is a significant concern affecting millions across the world, through contaminated water and food. Amongst the cereals, rice is known to accumulate more arsenic than other cereals and our research broadly aimed to reduce arsenic exposure through agronomic practices. Specifically, we are looking for PhD students interested in the following themes.

(1) Plant and soil factors affecting the uptake

(2) Rice root system responses to arsenic

(3) Optimisation of irrigation practices to reduce arsenic uptake in rice

(4) Bioaccessibility of arsenic across different rice types.

(5) Socio-economic impacts of arsenic on the affected population

For further information, please contact Dr Menon (m.menon@sheffield.ac.uk).