Sediment budget analysis for coastal management, west Dorset

• Published in: Land Surface Evaluation for Engineering Practice Vol. 18; pp. 181 - 187
• Main Authors: Lee, E. M., Brunsden, D.
• Format: Book Chapter
• Language: English
• Published: The Geological Society of London 01.01.2001
• Series: Geological Society, London, Engineering Geology Special Publications
• ISBN: 9781862390843; 1862390843
• ISSN: 0267-9914; 2041-4730
• DOI: 10.1144/GSL.ENG.2001.018.01.25

Background 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. Sediment inputs