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Information - GM4.2 Soil erosion as a geomorphological process (co-listed in HS)
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Event Information |
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Soil erosion has been widely studied as an agronomic problem, and as a major constituent of desertification, but has received less attention from geomorphologists, even though identified as one of the most significant erosional processes in many environments. Improved understanding of the detailed processes of runoff generation and sediment transport, and their interaction with vegetation cover, has now reached the stage where there is a good prospect of formally scaling up in time and space to the implications for the long-term evolution of soils and landscapes. Furthermore, spatially explicit datasets on controlling factors (topography, lithology, soils, climate) necessary to apply such approaches are now available on a continental and even global scale.
At present the theory of runoff generation in soil erosion models is based on the Richards’ equation or on the use of infiltration equations. Most experimental studies are for infiltrometer plots or small sub-catchments, providing a growing awareness of the issues of non-uniform production and a general decline in runoff with increasing catchment area, due to factors such as imperfect connectivity and short, localised bursts of intense rainfall. Vegetation plays a key role in creating and maintaining connectivity. Similarly for sediment transport, the strong non-linearity of the process makes forecasting very sensitive to micro-topography, and there is no current theory that examines the dynamic interaction between the details of form and process so that application of current models at the landscape scale remains problematic. As well as the issues of spatial up-scaling, there are comparable issues for up-scaling in time from the finest scales of rainfall measurement to the much coarser data that is widely available, both for current rainfall in many areas, and for forecasts from GCMs for future climate change.
Considering the lack of formal, theoretical approaches to upscaling it is not surprising that current landscape evolution models necessarily generalise these processes in terms of catchment area and gradient. As a consequence, such models are not fully informed by the current developments in soil erosion research. We invite contributions that can begin to mine this rich area, exploring experimental and theoretical approaches that can use the experiences of soil erosion research to improve our understanding of landscape and soil evolution.
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Preliminary List of Solicited Speakers |
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