Asian Age: Wetlands consist of marshes, swamps, bogs and similar areas. The functions of wetlands are filtering out of sediments and nutrients from the surface water and support all life forms through extensive food webs and bio-diversity.
Wetlands contribute to a number of important processes including movement of water into streams and rivers, decay of organic matter, release of sulphur, nitrogen and carbon into the atmosphere and the growth and development of different types of organisms. The direct benefits that human beings derive from wetlands include production of fish, timber and fresh water.
The indirect benefits include flood control, recharge of aquifer and storm protection. Wetlands have the capacity to retain excess floodwater during heavy rainfall. Wetland vegetations help control soil erosion, thus stabilising the shore line and protecting human lives from storm.
These retain nutrients by storing eutrophic parameters like nitrogen and phosphorous, besides helping absorption of sewage and purifying water supplies.
Wetlands occupy nearly 6.4 per cent (about 8.6 million sq. km) of the earth’s surface. About 50 per cent of the world’s wetlands have been lost due to careless human activities like urbanisation, drainage for agriculture and water system regulations, also developmental activities like industrialisation, excavation and filling and drilling.
India has got 67,429 wetlands covering an area of 4.1 million hectares. Out of these wetlands, 2175 are natural and the rest 65,254 are man-made. The country is blessed with numerous rivers and streams by virtue of its geography, varied terrain and climatic conditions.
India possesses a rich diversity of inland and coastal wetland habitats. Wetlands in India, excluding the rivers, account for 18.4 per cent of the countries geographic area, out of which nearly two-third is under paddy cultivation.
Most of the natural wetlands of the country are connected with the river systems, both in the north and south. The Himalayan Mountain range in the northern part of the country possesses a good number of lakes. The north-eastern and eastern part of India posses the massive flood plains of Ganga and Brahmaputra along with a large number of swamps, marshes and lakes.
Besides, these natural wetlands, there are a large number of wetlands in the country which are about 2.6 million hectares excluding paddy fields, rivers and streams. Some of the important wetlands include the Beas and the Sutlej in Punjab and Himachal Pradesh, the Koshi barrage in Bihar — Nepal Boarder and Hirakud Dam in Orissa.
The mangroves occupy 45 lakh hectares of land in the country. The wetlands of India, have been drained and transformed by anthropogenic activities like unplanned development of urban and industrial sites, agricultural activities, construction of highways, impoundments, resource extraction and dredge disposal causing long term economic and ecological loss.
According to the survey conducted by Wildlife Institute of India, 70 to 80 per cent of fresh water marshes and lakes in the gangetic flood plains have been lost during the last 50 years. As a matter of fact, during the last century, 50 per cent of India’s wetlands have been lost. The mangrove area of the country has been reduced from 7 lakh hectares in 1987 to 4.53 lakh hectares in 1995.
About 32 per cent of the wetlands in India has been lost primarily through hunting and associated disturbances, 22 per cent due to human settlements, 19 per cent due to fishing and 23 per cent through drainage from agriculture. Removal of vegetation in the catchment leading to soil erosion and siltation, contributes to about 15 per cent loss of wetlands. Pollution from the industries contributes to about 20 per cent loss of wetlands.
Some of the major human activities responsible for the destruction of wetlands in India include hydrologic alteration, agricultural activities, pollution, legal-policy failures, direct deforestation in wetlands, inundation by dammed reservoirs, degradation of water quality, global climate change effects, ground-water depletion and introduced species — extinction of native biota.
The conversion of wetlands, deltas and flood plains of most rivers in India to paddy fields is rampant, following “Green revolution” of the early 70’s. It is an ecological irony that as a result of this, the gross spatial extent of wetlands in the Indian subcontinent is greater today than it was 3,000 years ago owing to increased paddy fields treated as wetlands. The natural coastal wetlands are polluted to the extent that their fishery and recreational values are almost lost. Wetlands jurisdiction is diffused and falls under various departments like agriculture, fisheries, irrigation, revenue, tourism, water resources and local bodies.
The lack of a comprehensive wetland policy works against the interests of conservation of wetlands. It results in intended or unintended “spill-over,” further aggravating the problem.
The loss of wetland forests and coastal or riverine reduces the ability of wetlands to trap suspended sediments. The erratic alterations of impounded water levels, the potential for shoreline wetlands to develop and mitigate the losses of river bottom and riparian zones is minimal.
As a result of variable dam releases for power generation, the wetted area does not follow a predictable seasonal pattern, precluding development of a stable wetland flora and wildlife community.
Wetlands both contribute to and suffer from climate change. They are the single largest source of methane; a gas that is a major contributor to global warming. Water pumping continues to reduce ground-water level by 1.5 to 6 metres per year in some areas. River beds are now found to be dry for many months of the year. In view of the above scenario, it is very essential to properly manage the wetland of India, so that these invaluable resources can be properly utilised for our socio economic development and for keeping our environment healthy.
By-Dr Prafulla K. Jena, who is the chairman of the Institute of Advance Technology and Environmental Studies (New Delhi).
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