Rekawa Lagoon

In 1984 the Road Development Authority of Tangalle built a causeway called Kapuhenwela across the outlet canal; around 700 metres (2,300 ft) from the lagoon mouth to the inland.^[5] Water passes under the causeway through twenty three, 23 cm diameter pipes which greatly reduce the volume and speed of water entering and leaving the lagoon system.^[5] This causeway has prevented flushing of the lagoon by natural water flow, causing continues sedimentation in the lagoon.^[1] In 1999 a bridge of 6.2 metres (20 ft) in length was constructed in place of the part of the causeway in order to improve free water flow. After the Indian Ocean Tsunami in 2004, minor damage was inflicted on the causeway and it was renovated and replaced with eight cylindrical culverts with an average diameter of 79 cm (31 in) in 2005.^[1] Causeway itself and its modifications provoked concern over local resource users and environmentalists as the lagoon hydrology (ex; reduced flushing), salinity and there by the ecology (ex; reduction in shrimp catch) showed drastic changes and variations^[5] Before the construction of causeway, the effective channel cross section was 87 square metres (940 sq ft) which was then reduced to 25 m (82 ft) with the introduction of existing causeway structure with the bridge, a drop of 71% of effective channel cross section.^[1]

Around the lagoon, many mangrove species including Lumnitzera racemosa, Aegiceras corniculatum, Bruguiera gymnorhiza, Excoecaria agallocha, Rhizophora mcronata, Avicennia marina, and Avicennia officinalis are found.^[4] In addition to its ecological benefits (ex; shrimp and fish habitats), traditionally, Rekawa people have used mangroves for the benefit of the local community, but the increasing population has led to an increasing non-sustainable abuse of the resources. Mangroves have been exploited for timber for building dwellings and boats and fuel-wood for cooking in the area. Recent Researches discovered, even small scale cutting could affect the age composition and reproductive capacity of the mangrove forests in Rekawa lagoon.^[4]

A number of studies have been carried out recently on ecohydrology and mangroves of the Rekawa Lagoon. Ex;

1. Water balance and renewal time of Rekawa lagoon, Sri Lanka; a restorative approach.^[1]
2. Present status of small-scale exploitation of mangroves in Rekawa Lagoon, Sri Lanka.^[4]
3. Effects of industrialisation and urbanisation on the biology and water quality of three lagoons in southern Sri Lanka viz. Rekawa, Dondra and Galle with reference to water pollution and upstream land uses.^[6]
4. Applicability of Salinity Stratification Estimation by New Bulk Model for Two Choked Coastal Lagoons in Sri Lanka.^[7]
5. Variation of Natural Recruitments, Root Yield and Belowground Carbon Stocks between a Forest Gap and Uncut Forest in Rekawa Mangroves, Sri Lanka.^[8]