Vembanad Lake, A Ramsar site of Kerala
Lakes do act as an ecosystem helping the survival of thousands of living organisms in and around it. It serves the human population around it socially and economically. The conservation of a large a system of water body such as Vembanad Lake is very important as far as Kerala is concerned. The inclusion of this lake under the list of Ramsar sites justifies this.
The largest lake of Kerala, Vembanad Lake
Lakes are not merely a large water body, its existence influences the life of all living organisms in and around it. Among various lakes, Vembanad Lake is the largest one in Kerala. It spreads to a large area touching about four districts of the State, namely Thrissur, Ernakulam, Alappuzha and Kottayam.
Kerala coast, having a length of 590 km., has in its vicinity about thirty lakes small and large in size. The total area of these put together comes to roughly 2,42,000 hectares. These water bodies function as an abode of biodiversity. The genetic diversities of various living organisms depending on these lakes are well protected because of the specific features of these lakes. The human settlements around them are because of the benefits derived out of them.
Vembanad lake is the largest on the west coast of India. About seven rivers join this lake at different locations. It is connected to the Arabian sea. Nearness to the sea makes the water of the lake brackish at the lower reaches. At the upper reaches fresh water area could be seen because of water flowing from different rivers. During rainy seasons a major portion of the lake will have fresh water.Human interactions
Earlier records show that the Vembanad lake was having an area of 36,500 hectares. But within the last 150 years it got its size reduced due to several forms of reclamations. The encroachment into the lake started with the expansion of rice cultivation. People started filling the shallow areas. Protection walls were constructed to avoid water intrusion into the reclaimed areas. Because of the support from the rulers of that period for increasing rice cultivation, large areas were thus reclaimed for that purpose.
But it was later noticed that in those areas only one crop rice cultivation was possible, because of high water level in rainy season and brackish water intrusion in dry season. These activities were more in and around Kuttanad area in Alappuzha district. Years later, in 1955, Government constructed the Thottappally Spillway which controlled the water level raising problem to a large extent. After a few more years (in 1975), the Thanneermukkam barrage was constructed to control the brackish water intrusion. This barrage, 1250 meter in size, divided the Vembanad lake practically, into fresh and brackish water in terms of quality of water.
The net result of increase in rice cultivation in these areas resulted in the reduction of water covered area. Thus during the period from 1834 to 1975 more than 23,000 hectare of lake had been converted into other uses including rice cultivation, alternately rice and shrimp culture, coconut palm groves and other traditional industries. This works out to more than 63% of the total area of the lake.
For different developmental activities including the construction of port and other facilities about 719 hectare lake portion has been reclaimed during the period between 1920 to 2000. If all these accounted reclamations are taken together the total balance area of the lake become 12,675.94 hectares only. That is only 34.72 % of the original size of Vembanad lake.
The above details point toward the area-wise reduction of Vembanad lake. Parallel to this the depth also got reduced during theses periods. It is estimated that during the last fifty years the depth showed a reduction from 6.7 meters to 4.4 meters.reduction in depth is equally or more crucial as far as a water body is concerned. Both these reductions have affected the water carrying capacity of the system. In the beginning of the 20th century the capacity was estimated as 2.449 cubic km. while the same in 1985 was noted to be 0.559 cubic km. Bio-resources
Similar to any other lake, Vembanad also protects and help conserve the biodiversity in and around the lake. Thousands of people residing on the banks of this lake depend on it for their day to day needs. For hundreds of years they have been banking on this lake for their existence.
Fishery resources of this lake is well known. The Giant fresh water prawn of Vembanad fetches high value and is much sought after by the exporters.Clams were regularly excavated from the bottom in plenty by the local people and related industries were located in the neighboring localities. The clam excavation was mainly done by women workers. Thousands of families are surviving there depending on these resources. Due to environmental reasons and over-exploitation, the production of clams have drastically come down, and also the quality of the available clam shell deteriorated. These resources are there because of the peculiar ecosystem existing in the locality. The mangroves and the micro organisms (including the zoo and phytoplankton) are the most essential supporting elements for the growth of prawns, fishes and all other life system in the lake.A Ramsar Site
Vembanad lake was blessed with all these in the past. Based on its richness as a wetland ecosystem the lake has been listed among those wet lands to be protected under the Ramsar Convention 1971. The ecological importance of this lake has actually attracted people to settle on the banks of this water body. Thus the lake was actually contributing to the socio-economic needs of a society. Now also this lake is helping the society , perhaps, in a different manner. The earlier contributions of the lake still continue but in a reduced quantity.However, any further reduction to this wet land system will be detrimental to the country as well as to the people.
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