Hard Defenses
Static shoreline structures such as those constructed from timber, steel, concrete, asphalt and rubble. These involve linear structures such as sea walls, revetments and control structures of artificial headlands, offshore breastwork and groynes.
Soft Defenses
Mobile/ responsive defense measures, seek to work with nature rather than control it. Such structures may consist of sand or shingle beaches and dunes or banks, which may be natural or constructed, and may include control structures. These can include soft solutions of beach nourishment, cliff/dune stabilization, bypassing and managed retreat.
Reference
Dr.Ramesh.R. and Dr.Purvaja Ramachandran. 2007,’ENVIS – MoEF on Coastal Zone Management and Coastal Shelter belt Vol(6)’,pp 25.
Coastal Vegetation
A recurring pattern of dune, clifftop, mangrove and saltmarsh plant communities characterizes many rocky coasts. The plant communities comprise a diverse variety of plant species representing a number of plant families. In general, the plants are adapted to cope with the hot, dry conditions and saline environments. The communities form important habitat for a variety of native fauna. They also have a very important role stabilizing and trapping marine sediments and forming a protective buffer between the land and the sea .
http://www.environment.sa.gov.au/coasts/management.html
Many unique plants are found in dunes, coastal wetlands. Each plays a significant role in the ecology of the coast. Understanding the role and function of these plants helps to better understand the need to conserve these plants and their habitat. Salt marshes (in the temperate regions) and fore-dunes form a major part of coastal zones and are under the direct influence of seawater. Salt marshes consist of alluvial sediment deposits ranging from sandy to muddy substrates, which are flooded with seawater. Daily inundations with seawater following the tidal rhythm may take place, with the lower parts flooded more frequently and for longer periods than upper parts. Depending on the length of the period of seawater inundation and soil characteristics, including its mineral composition and microbial activity, the oxygen content and the redox potential of the soil falls.
On soft muddy substrates, higher plant life (Zostera) often starts below the level of the mean high water neap tide, sometimes mixed with pioneering Salicornia and Spartina. On slightly higher levels (sometimes only a few cm) other species occur. A sequence of belts with different salt-marsh species from lower to upper levels occurs. The direct influence on the seawater stops where litter deposited during winter storm surges forms a strandline. The influence of salt spray deposition may reach much further inland; it is most important for the development of the dune vegetation.
In India, coastal forests are restricted to the rainy parts of the Western Coastal plains and the Andaman and Nicobar Islands. The rainfall in this area is over 250cm with a short dry season. In these forests, trees reach great heights up to 60 meters or even above. Since the region is warm and wet throughout the year, it has a luxuriant vegetation of all kinds - trees, shrubs and creepers. There is no definite time to shed their leaves. As such these forests appear green all the year round
(http://gvc03c27.virtualclassroom.org/INDIA/coast/natveg.htm).
Mangroves
Mangroves are woody trees and shrubs that grow normally in places where river water mixes with seawater. These places are otherwise called estuarine or brackish water environment. Assemblages of mangrove woody trees and shrubs are called mangrove forests. Since mangrove forests are located in the estuarine environment they are intersected by a number of small tidal creeks and channels. In many cases large open brackish water bodies are also found associated with mangrove forests.
Mangrove forest and associated tidal creeks and canals and water bodies together constitute mangrove wetland. Mangrove wetlands are a characteristic feature of the tropical coastal areas
Reference
V. Selvam.,T. Ravishankar.,V.M. Karunagaran.,R. Ramasubramanian.,P. Eganathan . and A. K. Parida. 2005. ‘Toolkit for establishing Coastal Bioshield’, pp 117.
The health of the mangrove wetlands with reference to hydrological and soil conditions and the wealth of the mangrove wetlands in terms of area, species diversity, biomass and productivity are determined by
- Degree of protection against high-energy waves
- Quantity and duration of freshwater flow and sediment supply
- Larger tidal amplitude and
- Gently sloping coastal topography
Tropical Dry Evergreen Forest
The Tropical Dry Evergreen Forest (TDEF) is the indigenous forest of the coastal that becomes increasingly deciduous as one moves inland. It contains over 160 woody species of which around 70 are found within the pristine climax forest. This is predominantly composed of trees and shrubs that have thick dark green foliage throughout the year. There are six vegetative elements: trees, shrubs, lianas, epiphytes, herbs, and tuberous species. In the pristine state these components weave together to form a complex diverse habitat that is home to a myriad of animal species, mammals, birds, reptiles, amphibians, insects, as well as a host of microbes.