WORLD WETLAND DAY
Gunin Borah
(The writer teaches Geography in Biswanath College. He can be reached at borah.gunin@gmail.com)
Wetlands are dynamic aquatic ecosystems found all over the world. A wetland is an area of land that is saturated with water either permanently or seasonally. They occur where the water table is at or near the surface of the land, or where the land is covered by water. Wetlands are defined as, 'Lands transitional between terrestrial and aquatic ecosystems, where the water table is usually at or near the surface or the land covered by shallow water'. Many wetlands are transitional zones between uplands and aquatic ecosystems, although others are scattered across the landscape in upland depressions that collect water or in zones where groundwater water comes to the surface.
Wetlands can be freshwater, brackish (partly salty) or saline water.
The amount of water present in a wetland can vary greatly. Some wetlands are permanently flooded, while others are only seasonally flooded, but retain saturated soils throughout much of the 'unflooded' period. Some other wetlands are rarely flooded, but saturated soil conditions still are present long enough to support wetland-adapted plants and animals for hydric soil characteristics to develop.
Wetlands are known as Earth's kidneys because, like our kidneys, they serve a very important role in functioning or filtering water. Water moves through the wetlands, and the sediments and pollutants stick in the wetlands, making the water cleaner. Wetlands also help reduce flooding and prevent shoreline erosion.
Wetlands may be natural or human-made. The human-made wetlands may be constructed for water management purposes in urban areas. What's unique about all wetlands is that they contain vegetation that is specially adapted to such wet conditions. Plants that live in wetlands must be quite tolerant of wet, productive soil.
Different plant communities may be found in different types of wetlands, with each species adapted to its local hydrology. Wetland plants are often referred to as hydrophytes because they are specially adapted to grow in saturated soil. Many birds, insects, and other wildlife species are completely dependent on wetlands for critical stages in their life cycles, while many other species make use of wetlands for feeding, resting, or other life activities.
There are many different types of wetlands, each determined by hydrology, water chemistry, soils and plant species found there. Wetlands may be characterized as dominated by trees, shrubs, or herbaceous vegetation. They may be fed by precipitation, runoff, and groundwater, with water chemistry ranging from very acidic to alkaline.
Wetlands are crucial for food security. Between 300 to 400 million people live close to depend on wetlands. They support the cultivation of rice, a staple in the diet of half of the World's population. They also provide flood control, clean water, shoreline and shore protection, materials, medicines, and vital habitat.
As much as 87 per cent of the world's wetlands have been lost over the past 300 years, with much of this loss happening after 1900, despite their value to the human population. The World Wildlife Fund (WWF) continues to conserve and protect these valuable natural habitats.
The Brahmaputra valley and Barak valley in Assam have been blessed with innumerable freshwater lakes (Beels), ox-bow lakes (era-suti), marshy tracts, and thousands of ponds and tanks to hold the excessive rainfall the state experiences. These wetlands are vital to our water needs and food production. Besides, these serve as the habitat for thousands of species of flora and fauna. The wetlands of Assam cover an area of 1,400 sq Km area. There are around 3000 big and small wetlands scattered all across the state. But wetlands are under threat due to various factors like illegal encroachment, siltation, invasion of weeds, pollution, and also due to the lack of steps for law enforcement.
Assam State Remote Sensing Application Center has identified some 3513 wetlands in Assam. However, many of these wetlands are fast disappearing. Most rapid has been the decline in natural wetlands. There is no existence of more than 50 wetlands in recent surveys in the state, either due to the conversion of these wetlands for other activities or due to climate change impact.
According to the study by the North Eastern Space Application Centre (NESAC) in Assam, there are over 5900 sq. km. areas under the wetland ecosystem. In Assam, both the valley comprises a large number of wetlands- freshwater lakes (beels), ox-bow lakes (era-suti), marshy tracts, and pukhuris, which together continue to be an amazing and unique ecosystem. Leaving aside the areas occupied by rivers, Assam has over 3500 wetlands as identified by the Assam Remote Sensing Application Center a few years ago. Of these, again 861 are ox-bow lakes of cutoff meanders (era-suits). All these in addition to the several hundreds of marshy lands have originally provided vital space to the rising water of the Brahmaputra, Barak and their 100-odd tributaries during the Monsoon months. But, with time, a sizable portion of these wetlands have been encroached upon mainly by the migrant people from East Bengal, and present-day Bangladesh.
In urban areas like Guwahati, Jorhat, Tinsukia, Bongaigaon, Nalbari, Nagaon, Morigaon, and Silchar etc., rapid and unplanned urbanization, coupled with encroachment by land-hungry indigenous people have to lead to such a situation that, there is no space left for the rain waste of the residential areas to follow out. In Guwahati, the rapidly deteriorating status of Deepor Beel, and the impending death and disappearance of Borsola Beel, Sarusola Beel, Silsako Beel, and Bondajan are enough to comprehend this situation.
Climate change poses a threat to all ecosystems. The wetland ecosystem is the most vulnerable because wetlands are the least protected ecosystem. Destruction of habitats and loss of nesting sites has left many migratory birds to change their route of destination altogether. Climate change has added to the loss of habitat for many swampy birds. With rising temperatures, water bodies and swampy lands are drying up. With the increased temperature, evaporation also increases, which leads to depletion of surface water level resulting in depletion of aquatic life and vegetation cover. Degrading habitation as a result of climate change may become a critical component in the health of many mega-herbivores like rhinos, elephants and Asiatic water buffalo, experts warn.
Siltation is another major cause of the loss of wetlands. Heavy siltation after floods is adding to wetlands. Due to heavy siltation many wetlands change to grasslands and woodlands. Therefore, the majority of land cover has become the utmost priority for the management of the wetlands and protected areas. Wetland mapping is the first step to monitoring this important part of the ecosystem. Mapping of wetlands using geospatial tools can be done accurately at minimal costs and manpower used.
Monitoring at multiple spatial and temporal scales- support a better understanding of the ecosystem for continuous assessment and analysis of future trends. It is important that the North Eastern Space Application Centre (NESAC) with the joint initiative of the Department of Space and NE Council (NEC) has conducted a pilot project in this regard.
Identification and delineation of wetland areas need to be done on urgent footing, along with periodic monitoring of the physical status of the wetlands in protected areas. Wetlands need to be protected for their unique biodiversity. Apart from providing space for diverse life forms, these wetlands also help in reducing flood intensity by storing the surface rainwater. If properly managed, wetlands are going to be a source of immense wealth for our state, leading to the enrichment of the quality environment. Spreading awareness by initiating awareness programmes about the importance of wetlands is to be done among the indigenous people of the region. Effective collaborations among academicians and professionals including ecologists, watershed management specialists, planners and decision-makers for the overall management of wetlands are urgently needed.