Vembanad-Kol Wetland of Kerala is the longest lake in India. This place was designated as a Ramsar Site on August 9, 2002. It is the second-largest Ramsar Site in India, with the Sundarbans in West Bengal being the largest.
This lake is popular among the residents because it spans several districts in Kerala. It’s is known as Vembanadu Lake in Kottayam, Vaikom, Changanassery, Punnamada Lake in Alappuzha, Punnappra, Kuttanadu, and Kochi Lake in Kochi.
History of the Place
Vembanad Lake is called the Vembanad Kayal or the Vembanad Kol. Vembanad is also called Punnamada. The lake is known as the Heart of Kerala Backwater. The Vembanadu Wetland system formed a complex network of estuaries, lagoons, and canals. The Kumarakom Bird Sanctuary is located on the east coast of the lake.
Historical information demonstrates that till the turn of the 19th century, there was little anthropogenic pressure on the wetland complex.
Development of Cochin Port in 1838 catalyzed economic activities in the region. As an all-weather natural port, it is located strategically close to the business international sea routes from the Gulf to Singapore and Europe to the Far East circuits and the fastest-growing maritime gateway to peninsular India.
Large-scale reclamation of naturally fertile floodplain marshes was encouraged since the late 19th century and continued till the 1950s. Shallower wetland regions and marshes in the Kuttanad and Kol region were converted into polders, locally called padashekharams, to enable agriculture. Several spillways, regulators, and locks were constructed for regulating inflows and preventing salinity intrusion from the sea.
In 1976, Thaneermukom Barrage was constructed across Vembanad to prevent saline water intrusion into Kuttanad and control tidal action within its polders. Changing resource use patterns within the backwaters have made Vembanad-Kol wetlands a contested landscape, with wetland values and functions made subservient to economic exploitation.
Nowadays, Vembanad-Kol Wetland has become a significant tourist attraction.
Access to the Wetland
Reaching Vembanad lake is easily done by air, railways, and road routes. The nearest airport is the international airport suited in Kochi. It is about sixty kilometers from the main Vembanad destination. Vembanad can also be reached through the nearest railway terminus at Kottayam. The Kottayam railway station is almost thirteen kilometers from the place.
The bus route access to Vembanadu is through most of Kerala’s manor towns and cities. The government bus service is well managed, but private taxis and cars are also available. The Vembanad Wetland spans over 196 km in the north-south and 29 km in the east-west directions. Every village in this area can be accessed via water transport.
Topography of Area
The Vembanad lake is 96.5 km long. This wetland system covers an area of over 2033.02 km². The maximum length of this lake is 96.5 kilometers, while its maximum width is 14 kilometers. It has a surface area of 2,033 km2 and a maximum depth of 39 ft.
Geologically the catchment area has crystalline rocks in higher reaches. Tertiary sedimentary rocks, laterite capping over crystalline and sedimentary rocks aee mainly in the middle reaches, and recent & sub-recent sediments are in low-lying areas and river valleys.
The Alappuzha-Ponnani stretch is composed of pure alluvium of current residues with prominent paleo strandlines. Palaeo beach ridges or regression transgression features are prominent in the landmass lying from Cochin’s mouth to the south. One of these sets of details runs parallel to the Alappuzha-Cochin coastline and separates the Vembanad- Kuttanad area from the Lakshadweep sea.
Geology of Area
Vembanadu Lake rock types belong to the Precambrian crystalline. According to the geographical coordinate system, the place is located at 9°35′N 76°25′E.
Saucer-shaped basin flanked by laterite hills in the eastern and western margin. Soils are primarily of fluvial- estuarine origin, with a high component of black carbonaceous clay with peaty substratum in major areas.
Within the lake, the sediment texture is sandy loam. Content of sand, silt, and clay is 81.25%, 5 %, and 13.75%, respectively.
Hydrology of the Land
The lake’s minerals are grouped into allogenic, endogenic, and authigenic. This place has been declared as a National Waterway. The water of the Vembanad estuary is alkaline, well-oxygenated, and brackish. Its salinity varies from 4.5- 33.1 ppt.
Vembanad-Kol wetlands receive freshwater inflows from nine drainage basins. Rainfall is an important variable governing freshwater inflows into the wetland complex, as all the inflowing rivers are rainfed. The basin experiences two distinct rainy seasons–the Southwest monsoon (June to August) and the Northeast monsoon (September to December). About 60% of the rainfall occurs during the Southwest monsoon, 30% during the Northeast monsoon, and the remaining in the summer months.
Significant spatial and temporal variation exists within the basin, with the highlands generally receiving more rainfall than the midlands and lowlands.
The wetland’s flora consists of mangroves (44 species) and other aquatic species (180 species).
Vembanadu is a congregating area for both inhabitants (112 species) and migratory birds (70 species). Fauna includes fishes (58 species), shrimps and prawns (6 species), mollusks (4 species).
It is home to more than 20,000 waterfowls and is the third-largest in India. It is also an ideal habitat for shrimps.
Major species found are Channa striatus (murrel), a few species of catfish, freshwater prawn, Wallago Attu, and Etroplus suratensis. Black clam, frogs, snakes, tortoise, monitor lizard, and otter can also be found in the lake.
Islands in the Lake
A small group of islands is located in the lake portions. This includes:
- Willingdon Island is located in the Kochin Lake portion. Kochi Port is built around Willingdon Island and Vallarpadam Island.
Economic Evaluation of the Lake’s Resources
Above one million people live on the banks of the Vembanad lake and are directly or indirectly dependent on it for their livelihoods.
Major livelihood activities of the people living on the lake include agriculture, fishing, tourism, inland navigation, coir retting, and lime shell collection.
Deterioration of the Lake Environment
The uncontrolled mining of shells from the lake bed is posing a threat to the ecosystem.
The sewage effluents and the heavy load of organic material released from the neighboring areas, including a medical college at Alappuzha, are damaging the water and are responsible for the decrease in dissolved oxygen content in the water in the water body.
Vembanad lake faces a major ecological crisis and has reduced to 37 percent of its original area due to land reclamation. Breeding migration of M. rosenbergii and M. idella is affected by the salinity barrier, the Thannermukkam barrage.
There was also a reduction in fish and prawns’ upstream and downstream migration.
Habitat destruction through human interference, industrial pollution, over-exploitation of natural resources, illegal poaching, destruction of mangroves, and large-scale shrimp farming are major contributors to the destuction of the place.
Kerala Coastal Zone Management Authority announced that the spread of the lake, around 130.68 sq. km, in 1967, reduced to 9.382 sq. km in 2004 and 3.292 sq. km in 2011.
Restoration Plans for Vembanad-Kol Wetland
A few years ago, Vembanadu lake nets were removed to construct a tourist resort, and the fisherfolk went to court to stake their claim. Early this year, the Supreme Court ruled favor the fishing community.
The first phase of the eco-restoration project is to begin in January 2022 at Vembanadu Wetland. The Union Ministry of Environment, Forest, and Climate Change(MoEFCC) has sanctioned projects of Rs 680 crore to conserve the Vembanad-Kol Wetland system.
The project aims to develop a management planning framework for conservation and wise use of Vembanad-Kol backwaters. These activities are viewed as a Rebirth of Vembanad.