Koggala Lagoon

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Koggala Lagoon (Koggala Lake)
කොග්ගල කලපුව
Koggala Map.jpg
Map of Koggala lagoon with the locations of outlet and major freshwater inflows. Suburb marsh and paddy field areas are shown in different shaded patterns [1]
Location Galle District, Sri Lanka
Coordinates 6°0′N80°20′E / 6.000°N 80.333°E / 6.000; 80.333 Coordinates: 6°0′N80°20′E / 6.000°N 80.333°E / 6.000; 80.333
Type Lagoon
Primary inflows Warabokka-ela stream (Koggala-oya), Mudiyansege-ela stream, Thithagalla-ela stream, Heen-ela stream
Primary outflows Indian Ocean
Catchment area 55 square kilometres (21 sq mi)
Basin  countries Sri Lanka
Max. length4.8 km (3.0 mi)
Max. width2 km (1.2 mi)
Surface area7.27 square kilometres (2.81 sq mi)
Average depth1 metre (3.3 ft)
Max. depth3.7 metres (12 ft)
Surface elevation Sea level
Islands Mangrove Island (Madol Doova), Cinnaman Island, Kathdoova

Koggala Lagoon (Sinhala : කොග්ගල කලපුව)is a coastal waterbody located in Galle District,Southern Sri Lanka. It is situated near the town of Koggala and adjacent to the southern coast, about 110 km (68 mi) south of Colombo. The lagoon is embellished with eight ecologically rich small islands.

Contents

Features and location

The lagoon has a surface area of approximately 7.27 km2 (2.81 sq mi) measuring 4.8 kilometres (3.0 mi) in length and 2 kilometres (1.2 mi) in width. [2] The water depth ranges from 1.0 metre (3.3 ft) to 3.7 metres (12 ft). [3] The lagoon is largely rain fed and a number of streams are connected to it. Warabokka-ela stream (Koggala-oya) that enters the lagoon from the north-west is the main freshwater supply. [4] Kerena anicut, which was constructed combining two streams, Mudiyansege-ela stream and Thithagalla-ela stream, is the second largest freshwater inflow. [4] Heen-ela stream contributes a minor to the freshwater inflow [4] In addition to above four streams, Kahanda-ela stream, Gurukanda-ela stream and Thelambu-ela stream are also contributors for freshwater inflows but are presently abandoned with overgrown vegetation. [4] The only outlet of the lagoon is Pol-oya located at the southeast corner; a narrow 300 metres (980 ft) long canal, which connects the lagoon with the Indian Ocean.

Kathaluwa Bridge Koggala Kathaluwa Bridge Koggala.jpg
Kathaluwa Bridge Koggala


The lagoon has a hydro-catchment area of approximately 55 km2 (21 sq mi).2 [5] Various land use practices exist in the catchment, which mainly includes small-scale fishing industry and paddy farming. [6] The Koggala Export Processing Zone (KEPZ), is an industrial area with a surface area of 91 ha (220 acres) located within the catchment area of the lagoon. [4]

Tourism

The Koggala Lagoon is one of the main features for tourists who visit southern coastal areas in Sri Lanka with rich bio diversities and eco systems. [7] The Lagoon is scattered with eight small islands. [8] The islands consist of lush mangrove swamps. Anchored in mud, the mangrove roots are coated with a variety of creatures, including barnacles, oysters and crabs. [9] The dense, intertwining roots serve as nurseries for many fish species. There are seven islands in the lagoon, that can be reached by boat. [8] The most famous of the islands is ‘Madol Doova' (Mangrove Island Sinhala : මඩොල් දූව)’, which is described in detail by Martin Wickramasinghe in his novel, Madol Doova . Motor boats are available to hire to travel across the lagoon. [10] Tourists can witness the varying species of Mangrove, about ten of which are endemic to Sri Lanka. Wildlife of these islands inherited to a wide variety of flora and fauna, like monitor lizards and a number of birds.
In addition to wildlife and the scenery, Kathaluwa Buddhist Temple (Kathaluwa Purvarama Maha Vihara) is one of the main tourist attractions in the lagoon with Kandyan-style paintings dated 19th century. [10] Some images include colonial rulers and strangely Queen Victoria herself to commemorate her support for local Buddhism in the face of British missionary Christianity. [8]

Environmental problems

Destruction of the natural sand bar

The Koggala lagoon was once a paradise for its ecological community. However, human intervention has changed the fate of the lagoon with the destruction of the natural groyne (sand bar) during coastal defense activities in early 1990s. [5] This has been followed by unplanned removal of sand at the Pol-oya outlet near the lagoon mouth. The naturally built sand bar, which was perpendicular to the lagoon mouth controlled the seawater intrusion into the lagoon. With the opening of the lagoon mouth during the rainy season, rapid outflow of water began. However, the flow of seawater into the lagoon during the monsoon and high tides ceased the formation of sand bar again in the dry season. This natural dynamic rhythm causes high seasonal variations in most of the physical and chemical properties of lagoon water.
After the removal of the natural sand barrier, the formation of sand bar shifted towards the “Kathaluwa” bridge (highway bridge) by exposing the bridge to wave attack. Breaching the sand bar became increasingly difficult and erosion close to the bridge posed a risk to the bridge. Subsequently, in 1995, the Southern Provincial Council built a groyne system to protect the bridge from the wave attack. Another groyne was built in 2005 to control the erosion at the west side of the mouth due to prevailing groyne structure. Construction of the groyne provoked concern over local resource users and environmentalists as the lagoon hydrology and water quality showed drastic changes and variations. [5]

Threats to ecology and livelihoods

Due to the increased salinity of the lagoon, the ecological system has also been affected severely. Many freshwater species (Ex; Malpulutta kretseri , Etroplus suratensis ) is at the risk of being prone to growth difficulties or they might even face extinction if the breeding grounds are undesirable. [11]
Increased salinity in the lagoon water affects the growth cycles of shrimp. Recent studies suggested that shrimp and fish production in the lagoon had significantly decreased over the years. [11] Fishermen who engage in Koggala lagoon claimed that their harvest of large mud crabs has decreasing due to the increased salinity as a result of the groyne construction and open mouth throughout the year. Livelihoods of stilt fishermen were endangered too as the fish shoals start swimming inland waters and villagers use large nets to catch them in large batches since the lagoon area is now filled with saline water. [11]

Remedial action

As a solution to this environmental crisis the groyne system was modified in 2013 to allow the natural way of water flushing in the lagoon with proper salinity in the lagoon water. [11] The Practical Action (non-government organisation) together has sought to redress the problems by consulting and coordinating with the Coast Conservation Department, Galle District Secretariat and other authorities such as the Agricultural and Fisheries Departments. The project of rehabilitating the lagoon is also assisted by experts from the Moratuwa University, University of Ruhuna in Sri Lanka and Saitama University in Japan,. [12] [1]

Proposed structure Koggala Proposed structure Koggala.jpg
Proposed structure Koggala

Research work

A number of studies have been carried out over the past decade on lagoonal hydrology, hydrodynamics and fisheries. The majority of these projects have been done in collaboration with the University of Ruhuna, Moratuwa University and Saitama University.
Ex;

  1. Applicability of Salinity Stratification Estimation by New Bulk Model for Two Choked Coastal Lagoons in Sri Lanka. [13]
  2. Mud Crab (Scylla serrata) population changes in Koggala Lagoon, Sri Lanka since construction of the groyne system. [14]
  3. Effect of inlet morphometry changes on natural sensitivity and flushing time of the Koggala lagoon, Sri Lanka. [15]
  4. The Current status of density stratification of Koggala lagoon. [16]
  5. Restoration of Koggala lagoon: Modeling approach in evaluating lagoon water budget and flow characteristics. [4]
  6. Impact of rubble mound groyne structural interventions in restoration of Koggala lagoon, SriLanka. Numerical modeling approach. [1]
  7. Some hydrographic aspects of Koggala Lagoon with preliminary results on distribution of the marine bivalve Saccostrea forskalli: Pre-tsunami status. [17]

Related Research Articles

Brackish water Water with salinity between freshwater and seawater

Brackish water is water having more salinity than freshwater, but not as much as seawater. It may result from mixing seawater with fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak". Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment.

Estuary A partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

Mudflat Coastal wetlands

Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A recent global analysis suggested they are as extensive globally as mangroves. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of estuarine silts, clays and marine animal detritus. Most of the sediment within a mudflat is within the intertidal zone, and thus the flat is submerged and exposed approximately twice daily.

Yala National Park national park in Sri Lanka

Yala (යාල) National Park is the most visited and second largest national park in Sri Lanka, bordering the Indian Ocean. The park consists of five blocks, two of which are now open to the public, and also adjoining parks. The blocks have individual names such as, Ruhuna National Park, and Kumana National Park or 'Yala East' for the adjoining area. It is situated in the southeast region of the country, and lies in Southern Province and Uva Province. The park covers 979 square kilometres (378 sq mi) and is located about 300 kilometres (190 mi) from Colombo. Yala was designated as a wildlife sanctuary in 1900, and, along with Wilpattu was one of the first two national parks in Sri Lanka, having been designated in 1938. The park is best known for its variety of wild animals. It is important for the conservation of Sri Lankan elephants, Sri Lankan leopards and aquatic birds.

A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention.

Pulicat Lake brackish water

Pulicat Lagoon is the second largest brackish water lagoon in India, after Chilika Lake. Pulicat Lagoon is considered to be the second largest brackish water body in India measuring 759 square kilometres (293 sq mi). The Lagoon is one of the three important wetlands to attract North-East Monsoon rain clouds during October to December season to Tirupati Region. The lagoon comprises the following regions, which adds up 759 square kilometres (293 sq mi) according to Andhra Pradesh Forest Department: 1) Pulicat Lake 2) Marshy/Wetland Land Region (AP) 3) Venadu Reserve Forest (AP) 4) Pernadu Reserve Forest (AP) The lagoon was cut across in the middle by the Sriharikota Link Road, which divided the water body into lake and marshy land. The lake encompasses the Pulicat Lake Bird Sanctuary. The barrier island of Sriharikota separates the lake from the Bay of Bengal and is home to the Satish Dhawan Space Centre. Major part of the lake comes under Nellore district of Andhra Pradesh.

Chilika Lake lagoon in India

Chilika Lake is a brackish water lagoon, spread over the Puri, Khurda and Ganjam districts of Odisha state on the east coast of India, at the mouth of the Daya River, flowing into the Bay of Bengal, covering an area of over 1,100 km. It is the largest coastal lagoon in India and the second largest brackish water lagoon in the world after The New Caledonian barrier reef. It has been listed as a tentative UNESCO World Heritage site.

Bundala National Park National Park in Sri Lanka

Bundala National Park is an internationally important wintering ground for migratory water birds in Sri Lanka. Bundala harbors 197 species of birds, the highlight being the greater flamingo, which migrate in large flocks. Bundala was designated a wildlife sanctuary in 1969 and redesignated to a national park on 4 January 1993. In 1991 Bundala became the first wetland to be declared as a Ramsar site in Sri Lanka. In 2005 the national park was designated as a biosphere reserve by UNESCO, the fourth biosphere reserve in Sri Lanka. The national park is situated 245 kilometres (152 mi) southeast of Colombo.

Kokkilai lagoon is an estuarine lagoon in Mullaitivu District and Trincomalee District, north-east Sri Lanka. The town of Kokkilai is located on a sand bar between the lagoon and the Indian Ocean.

Vadamarachchi lagoon is a lagoon in Jaffna District, northern Sri Lanka. The lagoon is sometimes referred to as Thondamannar lagoon. The lagoon separates the Vadamarachchi region from the Valikamam and Thenmarachchi regions.

Chalai Lagoon is a lagoon in Mullaitivu District, north-east Sri Lanka. The town of Chalai is located on a sand bar between the lagoon and the Indian Ocean.

Nai Aru Lagoon is an estuarine lagoon in Mullaitivu District, north-east Sri Lanka.

Batticaloa Lagoon

Batticaloa Lagoon is a very large estuarine lagoon in Batticaloa District, eastern Sri Lanka. The city of Batticaloa is located on land between the lagoon and the Indian Ocean.Batticaloa district is flourished with three lagoons, such Batticaloa lagoon, Valaichchenai Lagoon and Vakari Lagoon. Among them, Batticaloa lagoon is the largest lagoon in Batticaloa District. Batticaloa lagoon is a long and narrow lagoon situated in the east coast of Sri Lanka with the total area of approximately 11,500 ha of water.

Puttalam Lagoon

The Puttalam Lagoon is a large 327 km2 (126 sq mi) lagoon in the Puttalam District, western Sri Lanka.

Ord River Floodplain

The Ord River floodplain is the floodplain of the lower Ord River in the Shire of Wyndham-East Kimberley, in the Kimberley region of northern Western Australia. It lies within the Victoria Bonaparte IBRA bioregion and contains river, seasonal creek, tidal mudflat and floodplain wetlands, with extensive stands of mangroves, that support saltwater crocodiles and many waterbirds. It is recognised as an internationally important wetland area, with 1,384 km2 of it designated on 7 June 1990 as Ramsar Site 477 under the Ramsar Convention on Wetlands.

Koggala Town in Southern Province, Sri Lanka

Koggala is a small coastal town, situated at the edge of alagoon on the south coast of Sri Lanka, located in Galle District, Southern Province, Sri Lanka, governed by an Urban Council. Koggala is bounded on one side by a reef, and on the other by a large lake, Koggala Lake, into which the numerous tributaries of the Koggala Oya drain. It is approximately 139 kilometres (86 mi) south of Colombo and is situated at an elevation of 3 metres (9.8 ft) above the sea level.

Amapá mangroves

The Amapá mangroves (NT1402) is an ecoregion along the Atlantic coast of the state of Amapá in Brazil. The low coastal plain has been formed from recent sedimentation, including sediments deposited by the rivers and sediments carried northward from the mouth of the Amazon River by strong currents and deposited by the tides. The extensive mangroves grow on the newly formed coastal mudflats and along the edges of estuaries. They merge into freshwater várzea flooded forests further inland. The ecoregion is generally well-preserved, although excessive extraction of natural resources including timber and shrimps is a concern.

Rekawa Lagoon

Rekawa Lagoon is a coastal waterbody located in Hambantota Districtt in the Southern Province, Sri Lanka and it is located 200 km (120 mi) south of Colombo. The lagoon possesses a rich biodiversity with a variety of flora and fauna.

Malala-Ambilikala Lagoons

Malala-Ambilikala lagoons are two interconnected coastal water-bodies located inside the Bundala National Park, Hambantota District in the Southern Province, Sri Lanka. It is 260 km (160 mi) from Colombo to the arid south. The Malala-Ambilikala lagoons are two of the three key lagoons located within the Bundala Ramsar wetlands.

References

  1. 1 2 3 Gunaratne, G.L.; Tanaka, N.; Amarasekara, P.; Priyadarshana, T.; Manatunge, J. 2011. Impact of rubble mound groyne structural interventions in restoration of Koggala lagoon, Sri Lanka. Numerical modeling approach. Journal of Coastal Conservation 15 (1): 113-121.
  2. CEA (Central Environmental Authority), 1995. Wetland site report and conservation management plan. Koggala lagoon under wetland conservation project. Sri Lanka Euroconsult, Sri Lanka.
  3. IWMI (International Water Management Institute), 2006. Sri Lanka Wetlands Database. http://dw.iwmi.org/ wetland/ wetlands info options.aspx?wetland name=Koggala%20Lagoon&wetland/(accessed 10 January 2009)
  4. 1 2 3 4 5 6 Gunaratne, G.L.; Norio, Tanaka; Amarasekara, P.; Priyadarshana, T.; Manatunge, J. 2010. Restoration of Koggala lagoon: Modeling approach in evaluating lagoon water budget and flow characteristics. Journal of Environmental Sciences 22(6):813-819.
  5. 1 2 3 Priyadarshana, T., Manatunge, T. and Wijeratne, N., 2007. Impacts and consequences of removal of the sand bar at the Koggala lagoon mounth and rehabilitation of the lagoon mouth to restore natural formation of the sand bar. Colombo: Practical Action.
  6. Amarasinghe O (1998) Profitability of current land use practices in five saltwater exclusion and drainage (SWED) schemes. Report of the SWED project under Southern Province Rural Development project, Sri Lanka
  7. http://www.koggalaexperience.com/
  8. 1 2 3 Prestige Sri Lanka – Koggala (2016) http://www.prestigesrilanka.com/koggala/ (accessed June 01, 2017)
  9. Amarasekara P., et al., 2016. Mud crab (Scylla serrata) population changes in Koggala Lagoon, Sri Lanka since construction of the groyne system. Aquatic Ecosystem Health and Management 19(1):83-91
  10. 1 2 Tripadvisor reviews – Koggala Lake (2017) https://www.tripadvisor.com.au/Attraction_Review-g1189030-d10392056-Reviews-Koggala_Lake-Koggala_Galle_District_Southern_Province.html (accessed June 01, 2017)
  11. 1 2 3 4 Rehabilitation of Koggala lagoon now almost on the verge of going barren (2013) http://www.dailymirror.lk/32456/rehabilitation-of-koggala-lagoon-now-almost-on-the-verge-of-going-barren#sthash.4XnXe1A6.dpuf (accessed 01/06/2017)
  12. Gunaratne, G.L.; Tanaka, N.; Amarasekara, P.; Priyadarshana, T.; Manatunge, J. 2011. Human intervention triggered changes to inlet hydrodynamics and tidal flushing of Koggala lagoon, Sri Lanka. ln: eds. Conditions for entrepreneurship in Sri Lanka: A Handbook. 347.
  13. Perera, G. L., et al. "Applicability of Salinity Stratification Estimation by New Bulk Model for Two Choked Coastal Lagoons in Sri Lanka." ACEPS 2015 (2015): 102.
  14. Amarasekara, G. P., et al. "Mud Crab (Scylla serrata) population changes in Koggala Lagoon, Sri Lanka since construction of the groyne system." Aquatic Ecosystem Health & Management 19.1 (2016): 83-91.
  15. Gunaratne, G. L., et al. "Effect of inlet morphometry changes on natural sensitivity and flushing time of the Koggala lagoon, Sri Lanka." Landscape and ecological engineering 10.1 (2014): 87-97.
  16. Furusato, E., et al. "The Current status of density stratification of Koggala lagoon." (2013).
  17. Gunawickrama, K.B.S.; Chandana, E.P.S. 2006. Some hydrographic aspects of Koggala Lagoon with preliminary results on distribution of the marine bivalve Saccostrea forskalli: Pre-tsunami status. Ruhuna Journal of Science 1: 16-23.