Earth Surface Science Research Theme
The Earth Surface Science theme deepens understanding of local to regional patterns and processes of change in environmental systems on timescales ranging from the Pleistocene to the present and near future. The theme’s work spans environments from catchment to coast, with a particular focus on glaciers, peatlands, river corridors and estuaries. Cross-cutting motifs include a multi-scale and multi-disciplinary approach; development and application of innovative techniques; and an emphasis on interactions and feedbacks leading to non-linear behaviour.
Our research extends across a wide spectrum of activity, but with an emphasis on three main foci supported by our research facilities:
a) Environmental change. Work in this area develops new tools for reconstructing past environments, and quantifies rates and patterns of environmental change. Research in conjunction with the Ancient Human Occupation of Britain Project has established new evidence for the age and environmental context of the earliest human occupation of Britain, extending the record of human presence over some 800,000 years and posing new questions concerning the abilities and adaptations of early humans to the environmental conditions of northern Europe (Simon Lewis). Major methodological contributions include the development and application of the Mutual Ostracod Temperature Range method for estimating palaeotemperatures using fossil nonmarine ostracods (Dave Horne). In glacial environments, studies of contemporary landscapes and processes are used to develop and refine techniques for reconstructing glacial dynamics and climatic sensitivity, including quantitatively assessing different approaches to glacier reconstruction and mass balance modelling (Simon Carr, Sven Lukas). We also use novel and innovative combinations of established macro-scale sedimentology and geophysics (ground-penetrating radar) to understand the genesis of the otherwise inaccessible interior of large lateral moraines in Alpine environments (Sven Lukas) and macro-scale sedimentology and micromorphology (Simon Carr, Sven Lukas). We have pushed the boundary of optically-stimulated luminescence dating to the hitherto uncharted territory of glaciolacustrine sediments, broadening the scope for establishing a detailed chronology of these key palaeoenvironmental archives (Sven Lukas). On time frames of 10s to 100s of years, we have used innovative spatial analysis of chronosequences to test fundamental theories on terrestrial successional dynamics (Lisa Belyea) following ‘resetting’ of the landscape by disturbance. On time frames of decades to individual floods, innovative integration of multi-scale satellite, airborne and ground data coupled with modelling have generated new insights into the controls, rates and styles of morphodynamic changes in fluvial systems (James Brasington, Angela Gurnell).
b) Water-sediment systems. Our research on contemporary processes focuses on understanding flows and transformations of matter in water-sediment systems. We have demonstrated the fundamental role of vegetation-flow-sediment interactions in controlling temperate river morphodynamics, including identification of the topographic signature of vegetation on river systems (Angela Gurnell) and its dependence on hydrochory, vegetation growth performance and the existence of a range of vegetated pioneer landforms that accelerate river morphological change (Angela Gurnell), and we have established relationships and feedbacks between coherent flow structures and physical habitats (Gemma Harvey). Complementary research on peatland systems has shown how multiple feedbacks involving vegetation, decomposition and peat hydraulic properties can interact either to stabilise or destabilise system dynamics (Lisa Belyea) and how the dominant mechanism controlling microtopography switches from water flow to evapotranspiration along a wet-to-dry climate gradient (Lisa Belyea). Work on sediment transport has elucidated the dynamics of in-channel sediment retention by aquatic macrophytes in lowland single-thread rivers (Geraldene Wharton, Kate Heppell) and hydrological and ecological techniques have been integrated in order to quantify the importance of novel nitrogen transformation processes in hyporheic and floodplain environments (Kate Heppell), and to assess the importance of vegetation for nutrient processing in river bed sediments (Kate Heppell). In the laboratory, experimental work using video image analysis has shown that cohesive sediment tracers interact with natural mud to produce mixed flocs with novel physical characteristics, throwing into question the use of these tracers for understanding and modelling sediment transport (Kate Spencer).
c) Ecosystem services, restoration and management. Much of our research informs human use and management of the environment and provides scientifically robust tools for practitioner use. In terms of physical processes, major contributions include modelling the consequences of land cover changes for water resources (James Brasington); reducing the uncertainty in flood inundation modelling (James Brasington); and quantifying the damaging physical impacts of alien invasive species on river beds and banks (Gemma Harvey). We have also developed techniques for rigorous river assessment and appraisal (Angela Gurnell, Kate Spencer, (Geraldene Wharton); contributed to the design of river restoration schemes (Geraldene Wharton); assessed the efficacy of stormwater sedimentation ponds in retaining and processing sediment-associated metal contaminants (Kate Spencer); and identified the medium-term consequences of inshore dredging and managed realignment for the fate of contaminants in coastal areas (Kate Spencer). With respect to greenhouse gases, we have developed a new, low-cost method for measuring methane emissions (Kate Heppell) and highlighted the challenges to upscaling methane emissions from heterogeneous wetland landscapes (Lisa Belyea).
The Theme is a partner in an Erasmus Mundus Joint Doctoral Programme ‘Science for Management of Rivers and their Tidal Systems’ (http://www.riverscience.eu/), which links our doctoral school with those in biology at the Freie Universitat and Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), and in environmental engineering at the University of Trento.
Facilities available within the research group include the Centre for Micromorphology and the Centre for the Aquatic and Terrestrial Environment.