Sediment budget analysis for coastal management, west Dorset
The identification and characterization of geomorphological units or systems is particularly important in the coastal zone. Indeed, the consequences of failure to appreciate the physical environment can be more acute on the coast, as rapid, major changes are a reality for land use planning and development. On the coast, it is often more useful to map the landscape in terms of sediment ‘cells’ (i.e. process units) rather than terrain units (i.e. landform units) as an understanding of the supply and transport of sediment (e.g. sand and shingle) is fundamental to dealing with many shoreline problems. Sediment is circulated in what often can be regarded, for practical purposes, as almost closed cells that are separated by boundaries across which little beach material is transferred. Each cell can be characterized in terms of the inputs, outputs, stores and sinks of sediment.
For example, to understand the development of a beach it is useful to consider it as a store of shingle or sand supplied from source areas on the adjacent coastline or offshore (Fig. 1). Beach building material might be supplied from the seabed, moved onshore by wave energy, or from rivers and eroding cliffs. This material is then redistributed along the shoreline by waves (‘longshore drift’), unless prevented by barriers such as headlands or breakwaters. Although longshore drift might be prevented by these barriers, some of the material can still be ‘lost’ to the system around the seaward end of the barriers or offshore, particularly during large storms.
Figures & Tables
This volume presents a collection of papers on techniques and case studies in land surface evaluation for engineering practice written by specialist practitioners in the field. The volume arose out of deliberations by the Second Working Party on Land Surface Evaluation set up by the Engineering Group of the Geological Society in January 1997 and chaired by Dr. J. S. Griffiths. The book examples of cost-effective methods for collecting land surface and near surface data prior to carrying further detailed ground investigations of engineering geologist, geotechnical engineers, geomorphologist and planners who have the responsibility for planning a designing investigations of potential sites of development.