Vembanad Lake, the hub of backwater tourism in Kerala and the largest wetland system in the country, may cease to exist in another 50 years as climate change aggravates the complex threats posed by land use changes, according to a study conducted by the National Centre for Earth Science Studies (NCESS) here.
The study on the environmental management action plan for eco-restoration of the lake and its inflowing rivers found that urbanisation, pollution and reclamation had whittled down the water mass by 40 per cent in area and 65 per cent in depth.
Presenting the findings at a workshop on climate change here, former scientist Ajayakumar Varma, who led the study, said 55,000 hectares of backwaters had been reclaimed and converted into polders for paddy cultivation. The carrying capacity of the lake had gone down from 2.45 to 0.56 cubic km, registering a decline of 78 per cent, while the urban agglomeration had increased five times over the last 50 years.
The study found that the inflow of sediments to the lake had gone up over the years.
The study of the land use pattern in Vembanad revealed that the area under plantations had increased from 27 to 40 per cent during the period from 1976 to 2010, while the area under settlements increased from 13 to 30 per cent. The forested area had shrunk from 59 to 30 per cent during the period.
Dr.Varma said the spatial and temporal variation in the rainfall pattern pointed to the influence of climate change factors on the river flow and wetland ecosystem.
The Pampa, he said, needed seven to nine times more than the present river flow of four cubic metres per sec, while the Muvattupuzha would experience saline intrusion if the present flow of 45- 55 cu m/s went down to 25 cu m/s. The report said the indiscriminate exploitation of groundwater and the contamination of surface and groundwater systems was likely to trigger a water crisis in the area. The situation could be aggravated by the impact of sea level rise on coastal surface and ground water systems.
The report has recommended the conservation of natural regions and micro watershed based land and water conservation programmes to enhance the carrying capacity of water bodies.