Coral reefs: shoreline protection

A major non-consumptive use of coral reefs enjoyed by human communities is the protection of the coast from prevailing weather. The physical structure of coral reefs dissipates much of the force of waves: up to 77% in the case of a discontinuous reef in Nicaragua, and more for continuous systems. Fore reef slopes often exhibit a spur and groove formation in which the grooves act as surge channels onto the reef flat. Much of the dampening of wave energy occurs because each incoming surge meets the backrush from the previous wave in mid channel. Grooves are usually areas of abundant coral growth.
 
Without coral reefs protecting the shoreline from currents, waves, and storms there will be loss of land due to erosion. In Indonesia, it was estimated that erosion costing between US$ 820?1,000,000 per km of coastline was caused through decreased coastal protection as a consequence of coral destruction (based on 0.2 m per year of coast erosion, 10% discount rate and a 25 year period). In the Maldives an artificial substitute breakwater - a 1 km pier ? designed to alleviate erosion cause din the main by coral mining cost around US$ 12,000,000 to construct.
 
Coral reefs also build up land. Many tropical, nations in the Indian and Pacific oceans with large human populations are situated on islands built by coral reefs. The capacity of coral reefs to dissipate wave energy creates lagoons and depositional sedimentary environments favourable for the growth of sea-grasses and mangrove ecosystems.