A2GEOGRAPHYREVISIONCOASTALENVIRONMENTS

8.4 SUSTAINABLEMANAGEMENTOFCOASTS

KEYTERMSANDDEFINITIONSCoastal protection refers to measures taken to prevent coastal erosion and/or flooding. To reduce erosion, several different forms of coastal protection are used. These can be divided into soft engineering and hard engineering.Gabion is a wire basket filled with rocks or stones used for stabilising slopes and protecting the base of cliffs in areas of coastal erosion.Groyne is a wooden or concrete barrier built at right-angles to a beach in order to block the movement of material along the beach by longshore drift. Groynes are usually successful in protecting individual beaches. However, as they prevent beach material from being transported along the coast they can starve beaches further down the coast of sand and shingle; hence these beaches may be at increased risk of wave erosion.

KEYTERMSANDDEFINITIONSHard engineering is any form of coastal (or river) protection scheme that involves altering the natural environment with concrete, stone, steel, metal e.g. the use of seawalls, gabions, groynes or revetments. Artificial structures are built in order to protect the natural environment from erosion.Managed retreat is allowing the coastline to retreat (erode) in certain areas, i.e. letting nature take its course in areas where the population density or the value of land is low.

KEYTERMSANDDEFINITIONSPolder is land reclaimed from the sea, especially common in the Netherlands.Revetment is a form of hard engineering in which the energy of the waves is absorbed by wooden planks or reflected by concrete structures.Sea defences are any form of measure, e.g. seawalls, rock armour, gabions and revetments, which help control coastal erosion and / or flooding.Soft engineering is any form of coastal (or river) protection that involves the use of natural means, e.g. sand dunes, salt marshes, tree planting and / or beach replenishment.

TOPICSUMMARYHuman pressures on coastal environments create the need for a variety of coastal management strategies.Shoreline management plans (SMPs) are designed to develop sustainable coastal defence schemes.Defence options include ‘do nothing’, maintain existing levels of coastal defence, improve the coastal defence and allow the retreat of the coast in selected areas.Coastal defence covers protection against coastal erosion (coast protection) and flooding by the sea.

TOPICSUMMARYThe function of a seawall is to prevent erosion and flooding.Cross-shore structures such as groynes, breakwaters, piers and strongpoints have been used for many decades.‘Managed retreat’ allows nature to take its course – erosion in some areas, deposition in others.Along many parts of the USA’s eastern seaboard coast, seawalls have protected buildings but not beaches.

TOPICSUMMARYThree factors put the east coast of the USA at particularly high risk from changing sea levels: first, the flat topography; second, rising sea levels; and third, extensive coastal development.Sand mining from Omaha beach, New Zealand, has been blamed for the Omaha sand spit changing shape and eroding badly in the early 1970s, before remedial groynes were built.The Great Barrier Reef is now heavily managed. Before it was managed the reef suffered from tourism, agriculture and recreational and commercial fishing.

ADDITIONALWORK1. Compare and contrast hard engineering measures with soft engineering measures.2. Explain why coastal areas need managing.3. Evaluate attempts to protect the eastern seaboard of the USA.4. Examine the impact of sand mining, as at Mangawhai–Pakiri, New Zealand.5. To what extent is it possible to manage the impacts of tourism in coastal areas? Use located examples to support your answer.6. Outline the main pressures affecting an area of coastline that you have studied.7. To what extent is it possible to manage coastal areas sustainably?

SUGGESTEDWEBSITESwww.unesco.org/csi/pub/source/ero9.htm for the protection of sand dunes in the Caribbean.www.aaas.org/international/africa/coralreefs/ch3.shtml for the protection of coral reefs.www.eurosion.org/shoreline/introduction.html for the Eurosion portal, which deals with shoreline management plans for Europe (there are 60 case studies on this site).www.ncl.ac.uk/tcmweb/tcm/czmlinks.htm for links to a number of coastal management organisations.www.csiwisepractices.org/?read=72 for sustainable coastal development in the Alexandria region of Egypt.