The coastal zone is home to an interesting array of bio-diversity due to the joining of two equally important yet very dissimilar environments, it is the place where the land meets the water, this makes for a hugely diverse natural environment in which many species and habitats exist. This rich diversity also fuels interest coming from all avenues of life, business, tourism, leisure, and interest from the natural realm such as; breeding fish find ideal mating grounds in estuaries, feeding birds thrive on the fish and their young while the waters flowing into the ocean off the land mass transport ever important nutrients which contribute to a nutrient rich environment in which shellfish flourish. Man’s activities have for centuries been drawn to these coastal environments for as long as history books can tell due to the ready availability of food, transport routes and a love for the area. Currently, ‘coastal squeeze’ or the encroachment of society on the coastal zone, is fuelled by an ever increasing popularity of beach based life which leads to development to accommodate the migrating masses and the business they bring. This makes for an interesting and challenging blend of management criteria when the pressures and needs of each of these components, or areas of vested interest, are taken into consideration. Many demands are made on few resources, and so a metaphorical tug of war can develop between man and nature.
Below are LINKS to examples of coastal processes which shape our coast at work.
- How waves with different energy levels can be either constructive or destructive.
- The process of longshore drift involving the swash and backwash of waves.
- The formation of bay-mouth bars and spits as a consequence of longshore drift.
- The processes of coastal erosion leading to caves, arches stacks and cliffs.
- How sand dunes migrate under the influence of the wind.
- How spring and neap tides are caused by the gravitational pull of the moon and sun.
Man has over the years gone by built towns, houses and planted in fields close to the shoreline, one onders if coastal protection would be such an issue had we not done so? However seeing that this is not the case, coastal protection does form an important part of environmental management. Forces working constantly barrage our coastline, waves, winds, expansion and contraction of heating and cooling rocks all contribute to the weathering and erosion seen on coastlines, these are also just the natural processes, as well as the above mentioned, the phenomenon of global warming causing the polar ice caps to melt which causes sea level rise is rapidly causing mankind to rethink coastal protection strategies.
The shoreline is a dynamic system where stability is maintained despite the continued movement of waves, tides, wind and sediment. The present configuration of the shoreline is now controlled by the various coastal defences', which mankind has put in place over the last 100 - 200 years. These have stopped or slowed the transport of sediments and reduced the ability of the shoreline to respond to natural forcing factors. Excerpt taken from Coast protection. To view a copy of Dover District Council's flood and coastal defence policy statement click here and scroll to the bottom of the page. Options for coastal defence.
A variety of protection methods exist in all of the above mentioned techniques such as floodgates, gabions, groynes, cliff stabilisation, seawalls rock armour, off shore breakwater construction and a variety of other options click here to see a page showing many types of methods.
Groynes in Sitages Wikipedia 2008
Humans' desire to protect their assests over the past few centuries has led to the development and implementation of a vast array of coastal protection methods, each of these methods however can have an adverse effect on the environment in which they have been constructed.
Coastal structures interfering with the littoral transport are the most common cause of coastal erosion. The presence of the structure has a series of effects: Trapping of sand on the upstream side of the structure takes sand out of the sediment budget, thus causing shore erosion along adjacent shorelines. Mostly, of course, on the lee side, but large structures may also cause (initial) erosion on the upstream side. Loss of sand to deep water Trapping of sand in entrance channels and outer harbours. The structures, which may cause this type of erosion, are:
Groynes and similar structures perpendicular to the shore Ports (see also Port breakwaters and coastal erosion) Inlet jetties at tidal inlets and river mouths detached breakwaters The accumulation and erosion patterns adjacent to coastal structures depend among other things on: The type of coastline, i.e. the wave climate and the orientation of the shoreline, The extent of the structure relative to the width of the surf-zone .