No abstract

This paper reviews the traditional approach to sediment budget studies in geomorphology, new approaches and more specifically the potential impact of new methodological advances. Each component of the budget is discussed including the spatial and volumetric estimations of erosion, deposition and storage and the precision and accuracy of flux rate estimation. Examples are used from recent work in Germany, The Netherlands and the UK and include the pedogenic approach to erosion estimation, remote sensing (LiDAR), geophysics and sediment-based dating techniques for flux rate estimation. The precision and accuracy of catchment sediment flux estimates based upon sediment storage is not only dependant upon volumetric accuracy but also on the precision and accuracy of sediment dating. In this area there has been a revolution with direct sediment dating techniques (TL, OSL, ESR) freeing budget studies from the constraints and biases of radiocarbon. Of particular importance is the use of cosmogenic nuclides for dating but which can also be used to derive long-term erosion rates but only using a steady state assumption. Finally a tentative initial application of the sediment budget approach to Pleistocene terrace staircase in unglaciated basins is discussed. It is argued that only now do we have the techniques available to be able to produce accurate sediment budget estimations at spatial scales greater than that of zero order basins and over time periods greater than that covered by direct observations.

This research project developed a terrace sequence model of alluvial landscape development to aid the management of the geoarchaeological resource within a temperate valley floor threatened by aggregate extraction. The model was created using the remote sensing techniques of light detection and ranging (lidar) and ground-penetrating radar (GPR), dovetailed with other archaeological and geological data sets within a geographical information system (GIS). Lidar first pulse (FP), last pulse (LP) and intensity models were used in a combination of ways to characterize the landscape. The topographic LP model was particularly effective at defining the major alluvial landforms, such as the higher terraces and palaeochannels. Lidar intensity data defined the palaeochannels, in response to the surface sediments' ability to absorb/reflect the lidar laser pulse. The three-dimensional architecture of the sediments infilling the valley floor was elucidated and modelled by GPR survey along geospatially referenced transect lines. These surveys had their time-slices calibrated through gouge coring along the transect lines, allowing depth slicing of the sediment stratigraphy. The GPR surveys accurately defined the depth of silty clay alluvium overlying the sands and gravels. Internal structure was revealed within the terrace gravels and at the margins of palaeochannels, allowing identification of bounding surfaces and construction of relative landform chronologies. However, GPR penetration into fine-grained palaeochannel fills was generally shallow, with little internal channel stratigraphy revealed. The lidar data sets and the GPR depth slices were integrated within ArcGIS and ArcScene. The distribution of the known and sometimes visible archaeological remains is considered in context of the geomorphology. It is demonstrated that erosion and sedimentation have ‘geologically filtered’ the archaeological resource and that some areas that have previously been considered archaeologically barren have high potential for both cultural and environmental archaeological remains

No abstract