Scientists are increasingly recognizing the importance of extreme events in shaping the landscape. This is particularly true for river erosion which happens during short-lived events. During floods, the sediment particles lying on the bed of rivers are put in motion: through successive impacts, they erode the exposed bedrock. Research at the School of GeoSciences is aiming at investigating the most extremes of these events.
Hazard research in the Land Surface Dynamics group collaborates with other colleagues in Edinburgh who are modelling storm event frequency (Hegerl) and evolution of the Indian monsoon (Bollasina), and other colleagues using a range of techniques such as cosmogenic nuclides for recording long term sediment flux rates (Hein).
Extreme Floods in mountain ranges
The geomorphic record of extreme flood events enables accurate reconstructions of river discharge and even precipitation amounts which usually depend on low resolution meteorological satellite data. This increased resolution enables improved understanding of run-off processes and the links to landslide and debris flow activity on hillslopes. Current projects in Himalaya in collaboration with Indian colleagues.
Extreme floods generated by glacial melt
The most devastating floods on earth are those associated with release of glacial meltwater, either from the front of mountain glaciers (Glacial Outburst Floods – GLOFS) or from beneath ice sheets, particularly in volcanic parts of the world such as Iceland which generate Jokulhaups. Current projects in Iceland and Himalaya.
Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland
ERC Baynes, M Attal, S Niedermann, LA Kirstein, AJ Dugmore, M Naylor
Proceedings of the National Academy of Sciences of the United States of America (2015)
Catastrophic impact of extreme flood events on the morphology and evolution of the lower Jökulsá á Fjöllum (northeast Iceland) during the Holocene
ERC Baynes, M Attal, AJ Dugmore, LA Kirstein, KA Whaler
Geomorphology 250, 422-436 (2015)
Tectonics from topography
The increased availability of high resolution digital topography in the last decade is enabling the development of new analytical tools for interpreting the landscape for fault activity on timescales beyond the historical. Hence faults are being identified as having been active on the 103-105 yr timescale that are inactive historically with important implications for seismic hazard. This technique has been applied in Italy, Turkey and the Himalaya.
InSAR records surface change
Interferometric synthetic aperture radar (InSAR) has traditionally been applied to understanding ground motions following earthquakes. New technical advances are now enabling InSAR to record the retreat of glaciers, the deflation of glaciers following the catastrophic release of meltwater, and changes in surface form following floods, landslides and debris flows. Current applications are recording the changing form of Himalayan glaciers and supporting field analysis of the impacts of extreme floods in mountain ranges.
This toolbox is developed as a framework for implementing the latest developments in topographic analysis, for developing new topographic analysis techniques, for numerical modelling of landscapes, to improve the speed and performance of topographic analysis versus other tools (e.g., commercial GIS software), and to enable reproducible topographic analysis in the research context.
Salt marsh stability in the face of rising sea level [In a Nutshell]
Himalayan Storms (2010) [In a Nutshell] Dan Hobley, Hugh Sinclair and Simon Mudd traced reconstructed a convective storm event in the Indian Himalaya by mapping debris flows and peak flow geometry. These can give insight into the nature of convective storms.
Icelandic Megafloods [YouTube]: Extreme flood events occur regularly in Iceland as a result of volcanic activity under ice caps. The understanding developed from Iceland of the impacts of extreme flooding can then be applied to other locations where similar extreme events are thought to have occurred, such as the North-West USA, the Himalayas and Mars.