World Wetlands Day 2002: Sri Lanka


This is to inform you of the following event:

World Wetlands Day 2002 - Media briefing

In order to commemorate this important global event and to facilitate increasing public awareness on the significance of sustainable management of our wetlands, IUCN Sri Lanka has organised a media briefing, in collaboration with the Integrated Resources Management Project (IRMP) of the Central Environmental Authority

Date: 25 January 2002
Time: 10.30 a.m - 12.30 p.m.
Venue: Council Room, Sri Lanka Association for the Advancement of Science (SLAAS), "Vidya Mandiraya", 120/10, Wijerama Mawatha, Colombo 7.

The presentations will be made by: Dr.Jayampathy Samarakoon ( IRMP/CEA) on "The signifance of Wetlands in today's world" Mr.Pandula Endagama on "Wetlands - an important part of our Cultural Heritage" and Dr. Channa Bambaradeniya on "Wetlands and Biodiversity"

A Wetland toolkit containing information on the Ramsar Convention and World Wetlands Day, Globally significant wetlands, Sri Lanka's wetlands and their conservation value will be disseminated at the Media Briefing. In addition, the soft launching of a publication on the biodiversity of Sri Lankas first Ramsar site - Bundala Wetlands ("GUIDE TO BUNDALA" - text compiled and edited by Channa Bambaradeniya) published by IUCN Sri Lanka in collaboration with the Department of Wildlife Conservation and the Ramsar Bureau will also be undertaken at this event.

On the 2nd February, The visitor centre at the Bundala National Park will be innaugurated by the Divisional Secretariate of the Hambanthota District (where this wetland is located). This centre was developed with awareness material and exhibits by IUCN SL, under a Ramsar small grant. It would be followed with an awareness workshop on the Bundala Wetland and the WWD for Government officials in the Hambanthota District.


Channa Bambaradeniya, Ph.D
Head - Biodiversity Unit
IUCN - The World Conservation Union
Sri Lanka Country Office


Text compiled by: Channa N.B.Bambaradeniya
IUCN - The World Conservation Union,
Sri Lanka Country office

This note containing general information on wetlands was prepared for a media briefing by IUCN Sri Lanka to mark the World Wetlands Day of 2002
( 2nd February: Theme - Wetlands Water, Life and Culture)
© IUCN - The World Conservation Union, Sri Lanka Country Office, 53, Horton Place, Colombo 7.


On the 2nd of February 1971 a significant milestone on the conservation of wetland ecosystems was achieved in the city of RAMSAR in Iran, where a global consensus was adopted to identify and protect wetlands of international importance especially as waterfowl habitat. Today, the Convention on Wetlands (popularly known as the RAMSAR Convention) serves as an intergovernmental treaty which provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources. There are presently 130 Contracting Parties to the Convention, with 1112 wetland sites, totaling 89.37 million hectares, designated for inclusion in the RAMSAR List of Wetlands of International Importance. Sri Lanka became a signatory to the RAMSAR Convention in 1991 by declaring the Bundala Lagoon system as its first RAMSAR wetland site.

In order to commemorate this global convention on wetland conservation, the 2nd February has been declared World Wetlands Day by the RAMSAR Bureau. RAMSAR's World Wetlands day 2002 is focussed on the cultural heritage of Wetlands and the need for management strategies that will safeguard this heritage as well as the natural values and functions of the wetlands.


1. Bundala National Park

Located in the Hambanthota District, Bundala was declared a Ramsar site in 1991, owing to the high species richness of waterfowl, including migratory species. The principal wetland type in the Bundala National Park is a system of lagoons.

2. Annaiwilundawa Sanctuary

Located in the Puttalam District. Annaiwilundawa was declared as a Ramsar site in August, 2001, considering its rich biological diversity and historic/cultural significance. The principal wetland type in Annaiwilundawa is a system of ancient cascading tanks established in the 12th Century.


What are wetlands?

Among the many definitions of wetlands in use throughout the world, the broadest and hence the most widely used on an international scale, is provided by the RAMSAR Convention. Designed to provide international protection to the widest possible group of wetland ecosystems, the RAMSAR Convention defines wetlands as: " areas of marsh, fen, Peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed the 6 meters"

The Wetlands of Sri Lanka that fits into the definition given by the RAMSAR Convention could be divided into three broad categories:

  • Inland fresh water wetlands (eg.rivers, stream, marshes, swamp forests, and "Villus").
  • Salt water wetlands (eg.lagoons, estuaries, mangroves, sea grass beds and coral reefs).
  • Man-made wetlands (eg. tanks, reservoirs, rice fields, salterns).

A short description of major wetland types in Sri Lanka is given below.

Inland fresh water wetlands

Streams and rivers

Sri Lanka has an extensive network of rivers and streams that drains a total of 103 distinct natural river basins. In terms of length, these flowing water bodies cover more than 4500 km. Mahaweli, Walawe and Kelani rivers originate from the central highlands and flows through all three peneplains. The river basins originating in the wet highlands are perennial while many of those in the dry zone are seasonal. The river Mahaweli accounts for the largest basin, covering 16% of the island and thereby has a high socio- economic and ecological value.

The "Villu" wetlands

Although there are no large natural lakes in Sri Lanka, there are several flood plain lakes, commonly referred to as "Villus", which cover a total area of 12500 ha. Often they are cut-off former river bends. Many of the larger "Villus" are located in the Mahaweli floodplain in the East. A typical example is the inter-connected Handapan and Pendiya Villus (796 ha) which is the largest of the entire Mahaweli Villu system. The Wilpattu National Park also contains several Villu ecosystems.

Fresh water Marshes

These are shallow inland depressions located mainly in rural areas either connected to a river or receiving water through surface run-off river flood water and ground water seepage. Partially decomposed organic material in such marshes forms peat, characterized by water logged sticky soil. A typical example is the Muthurajawela Marsh, which is the largest peat bog in Sri Lanka.

Fresh water Swamp Forest

This is a late successional stage of a freshwater marsh ecosystem, comprising of trees that are adapted to grow in shallow stagnant water. Swamp forests are seasonally inundated with river water. It is the most rare wetland type in Sri Lanka and a good example is the Walauwa Watta Wathurana Swamp forest (12 ha) located in the Kalu river basin.

Salt water wetlands

Estuaries and Mangroves

These are inter-connected coastal wetland types. Estuaries are formed in places where rivers enter the sea. The daily tidal fluctuation and the intermediate salinity between salt and freshwater (commonly termed "brackish water") are main characteristics of this ecosystem. There are about 45 estuaries in Sri Lanka. The mangroves comprise very diverse plant communities that are adapted to grow in unstable conditions of estuarine habitat. The mangroves are a rapidly diminishing wetland type in Sri Lanka, consisting of less than 10,000 ha of discontinuously distributed patches along the coastline. Typical example of estuaries with mangrove wetlands in Sri Lanka includes the Maduganga estuary and the Bentota estuary.


These are salt or brackish water coastal wetlands separated from the sea by a low sand bank with one or more relatively narrow permanent or seasonal outlets to the sea. These can also harbour other coastal wetland types such as mangroves, mud flats and sea grass beds. Around 42 lagoons are found around the coast in Sri Lanka. Examples include the Bundala Lagoon, Mundel Lake, and Kalametiya Lagoon.

Coral reefs and Sea grass beds

These are two important sub-tidal marine wetlands (below 6 m in depth) in Sri Lanka. Coral reefs consists of calcareous structures secreted by a group of marine invertebrates. Coral reefs are famous for their spectacular beauty and are rich in biological diversity that could be compared to a tropical rainforest. Extensive coral reef habitats occur in the Gulf of Mannar, Trincomalee to Kalmunai in the East Coast and in several areas of the South and Southwestern coast. (eg. Rumassala and Hikkaduwa)

Sea grass beds are composed of rooted, seed bearing marine plants. These occur in shallow, sheltered marine waters, as well as in lagoons and estuaries. Most extensive sea grass beds occur in the northwest coastal waters of Sri Lanka (eg. Kalpitiya to Mannar).

Man-made Wetlands

Tanks and Reservoirs

Although there are no natural lakes in Sri Lanka, an array of ancient irrigation tanks have substituted the former wetland type. Numbering nearly 10,000, these man-made wetlands depict the rich cultural heritage of Sri Lanka. The major irrigation reservoirs (each more than 200 ha) cover an area of 7820 ha, while the seasonal/minor irrigation tanks (each less than 200 ha) account for 52250 ha. Typical ancient irrigation tanks include the Parakrama Samudraya and the Minneriya tank.

Rice Fields

Rice fields are characterized by the presence of a standing water body, which is temporary and seasonal. Hence, flooded rice fields can be considered agronomically managed marshes. They are temporary and seasonal aquatic habitats, managed with a variable degree of intensity. The total area under rice cultivation at present is about 780,000 ha (approximately12% of the total land area), which is distributed over all the agro-ecological regions except for areas located at very high elevation. Approximately 75% of rice lands in Sri Lanka are located within inland valley systems of varying form and size while the rest are found in alluvial plains and also on terraced uplands in the interior.

Significance of wetlands in Sri Lanka

All wetlands comprise a mixture of soils, water, plants and animals. The interactions between these elements allow wetlands to perform several functions that are beneficial to mankind, while generating a healthy wildlife, fisheries and forest resources. The combination of these functions, together with the rich biological diversity and cultural heritage of wetlands makes these ecosystems invaluable to people all over the world. The loss of wetlands results in the eradication of these benefits, leading to harmful consequences on human welfare and to the extinction of species that are ecologically dependant on wetlands. The importance of wetlands can be elaborated under three major categories; uses, functions and attributes.

Wetland Uses

Uses are direct economic benefits gained by people through exploitation of wetland resources. Major wetland uses could be highlighted as follows:

Uses/Products Examples from Sri Lanka Wetlands exploited
Water supply and transportation
a) For Domestic supply
b) For irrigation
Labugama, KalatuwawaMinneriya tank, Mahaweli river Rivers, streams, tanks, reservoirs
Agricultural products for human consumption Rice, Leafy vegetables Rice fields, marshes, tanks
Medicinal herbs "Lunuwarana" herb Marshes
Raw material for handicrafts and mats "Kaduru" wood for masks, Pandanus leaves Marshes, Mangroves
Hydro-electricity Victoria, Randenigala and Rantambe reservoirs Waterfalls, Reservoirs
Fish and crustaceans for consumption Edible Freshwater and brackish water fish and crustacean species Rivers, tanks, reservoirs, lagoons, estuaries
Fish and plants of ornamental value Black Ruby Barb, Cherry Barb, Cryptocoryne, Aponogeton Streams, marshes
Material for religious ceremonies/offerings Nelum/Olu/Manel flowers Marshes, Ponds
Salt Hambanthota lagoon Salterns
Recreation/tourism Bundala wetlands Tanks, Lagoons, waterfalls

Wetland Functions

These are benefits of wetlands that support or protect human activity without being used directly. Major wetland functions could be summarized as follows:

Major Functions Contributory Wetlands
Mitigation of floods Marshes, Tanks, Rice fields
Protection from storms/prevention of coastal erosion Mangroves, Coral reefs
Retention of sediments Mangrove, Coastal marshes
Purification of water/removal of toxic compounds Marshes
Act as a Carbon Sink Marshes
Breeding habitats of edible fish Mangroves, Marshes, Sea grass beds

Wetland Attributes

These are benefits to a country that do not provide direct economic benefits. Two important wetland attributes include sustenance of a rich biological diversity and cultural heritage.


The biodiversity of wetlands in Sri Lanka is clearly depicted by the rich array of wetland ecosystem/habitat types, and the higher number of animal and plant species that they harbour. For instance, among the total inland vertebrate species in Sri Lanka, about 30% are ecologically dependent on wetlands. Among the migratory birds that visit Sri Lanka annually, more than 50% are directly dependent on wetlands for food and shelter. Furthermore, the future survival of approximately 32% of the nationally threatened vertebrate faunal species in Sri Lanka is dependent on wetland ecosystems of the island.

Cultural heritage

In Sri Lanka, wetlands such as rivers and floodplains have been the cradle of historic civilizations. The man-made wetlands in Sri Lanka, especially the ancient irrigation tanks and rice fields, clearly highlights the rich cultural heritage associated with wetlands. It is generally believed that Indo-Aryan immigrants started rice cultivation in Sri Lanka more than 2500 years ago. This was a period at which a settled civilization developed in the dry zone and an elaborate irrigation system was established for rice cultivation. The earliest references to the establishment of tanks to conserve water for irrigation of rice in Sri Lanka was about 420 BC. Considering the size of these tanks and the network of neatly built sluices/canals, the technology of our ancestral irrigation engineers is truly astonishing.

Threats to Wetlands in Sri Lanka

A majority of the wetlands in Sri Lanka are facing various threats that are posed by harmful human activities. These could be summarized under four major categories; habitat deterioration/degradation, direct loss/exploitation of species, spread of invasive alien species and natural phenomena.

Habitat deterioration/degradation

Several factors have resulted in the deterioration and degradation of the quality of wetlands, which could be highlighted as follows:

Contributory Factors Impacts Affected wetlands
Reclamation Loss of wetlands and their biodiversity Urban Marshes (eg.Bellanwila-Attidiya, Muthurajawela)
Clearing of vegetation Loss of habitats and species Mangroves (eg. Mangroves in the Coastal areas of the Puttalam District)
Water pollution
- Organic pollution
- Other Chemical effluents
- Sewage disposal
Loss of species
Loss of species, Harmful impacts on humans
Marshes (eg. Muthurajawela)
Rivers (eg. Kelani river)
Tanks, Marshes, Estuaries (eg. Parakrama Samudraya, Beira lake)
Garbage disposal Eutrophication, spread of harmful diseases Marshes (eg. Muthurajawela, Bellanwila-Attidiya)
Regulation of water flow (Dams) Gradual disappearance of lowland wetlands Villu ecosystems in the Mahaweli Floodplain
Mining (Sand/coral) Loss of habitats and species Rivers, Coral reefs

Direct loss/exploitation of species

Overexploitation of wetland plants and animals has resulted in several species facing the risk of extinction. Factors that contribute to this threat could be highlighted as follows:

Contributory Factors Impacts Affected Species
Poaching (for consumption) Reduction of populations of targeted birds and mammals Waterfowl (Ducks and Teals), Otter
Ornamental fish trade Reduction of local fish populations Black Ruby Barb, Cherry Barb, Mono etc.
Ornamental plant Trade Reduction of aquatic plant populations and loss of habitats for aquatic animals Cryptocoryne spp., Aponogeton spp.
Scientific Research Reduction of aquatic animals Stream dwelling fish
Water Pollution Reduction of aquatic animals, Human health impacts Fish, Amphibians, piscivorous birds, Otter

Spread of invasive alien species (IAS)

The introduction of several species of exotic aquatic animals and plants that have eventually escaped into wild habitats are posing a serious threat to native aquatic biodiversity. Observations made during the past five years have enabled to document 10 species of invasive alien fauna (8 species of fish, one turtle and one aquatic mollusc) and 12 species of invasive alien flora, spreading in different wetland ecosystems throughout Sri Lanka. Among them, 4 species of fauna (Tilapia - Oreochromis mossambicus, Walking catfish - Clarias batrachus, Rainbow Trout - Oncorhynchus mykiss and Mosquito fish - Gambusia affinis) and two species of flora (Water hyacinth - Eichhornia crassipes and Giant mimosa - Mimosa pigra) are included in the list of the world's 100 worst invasive alien species. The ornamental fish trade has been the sole contributory factor to the introduction of invasive alien aquatic species into Sri Lanka. The major impacts of IAS could be summarized as follows:

Impacts of IAS Example of Invasive species Affected native wetland species/ecosystems
Direct exploitation or destruction of native species Predatory species (Trout, Clown-knife fish, Walking catfish, Red-eared slider turtle) Endemic freshwater fish
Superior competitors for resources Tilapia, Water hyacinth Native aquatic fish and plants
Deterioration of the quality of wetlands Salvinia, Water hyacinth Tanks, Marshes, Estuaries
Agricultural pests/weeds Apple Snail, Water hyacinth, Salvinia, Hydrilla Rice fields, Tanks, Irrigation canals

Natural Phenomena

Wetlands are threatened by natural phenomena as well. For instance, the recent prolonged drought resulted in the drying off of several tanks, streams, marshes and lagoons, causing death to several species of wetland animals. The rise of sea water temperature (due to climate change) resulted in the bleaching of coral reefs, especially in the south western part of Sri Lanka. For example, the Hikkaduwa Coral Reef, which was once a rich habitat, is now virtually a dead reef.

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