Wetlands of Assam

Photo: Son Beel, about 79.4 KM from Silchar, Assam (Source: Internet)

WETLANDS IN ASSAM

Wetlands are unique ecosystems which provide water and habitat for a diverse range of plants and animals. Natural wetlands occur where surface water collects or where groundwater discharges to the surface. Due to the water filtration processes which occur at wetlands, they are sometimes referred to as the ‘kidneys’ of a catchment area.

Wetlands that contain water all year round are called permanent wetlands and those that fill seasonally are called temporal wetlands. Others, called ephemeral wetlands, only contain water after heavy rains or during floods, perhaps once every few years.

Since wetlands are so common and found almost everywhere. During the 1970s, people began to recognize the benefits of wetlands. In addition to hosting a wide variety of plant and animal life, wetlands also provide water storage, filtration and offer us protection from floods. The government also has recently put focus on restoration and wetland creation.

Wetland environments have a variety of important functions in natural and urban areas including: Wildlife support, Water detention, Improving water quality, Flood control, Erosion control, Groundwater aquifer recharge, Coastal buffer zones, Natural fire breaks, Education, Eco–tourism, Recreation

Cultural significance

The valley of the river Brahmaputra with its innumerable fresh water lakes (locally called beel), or ox-bow lakes (era suti), marshy tracts and seasonally flooded plains and hundreds of riverine sand_bars and islands was, till recently, an ideal wetland eco-system which contained specialised wetland animals like the fresh water dolphin, dugong and the great Indian one-horned rhino and reptiles like the crocodile, the winter monitor lizard and few species of turtles. All these creatures are either extinct or highly endangered at present.

The various types of wetlands found in Assam are as folloew:

Lakes / Ponds :

In Assam, there are 690 lakes and ponds as recorded. These lakes /ponds cover an area of 15494.00 ha which constitutes 0.20 percent of the total geographical area of the state and 15.30 percent of the total area under wetlands. The smallest of them measures 2.50 ha while the largest one has 882.50 ha of areal coverage. Majority of this type of wetlands have water with low turbidity.

District- wise 3513 numbers of wetlands are identified in Assam by Assam Remote Sensing Application Centre, Assam

Ox-bow Lakes / Cut-off Meanders:

A total 861 number of ox-bow lakes/cut-off meanders are observed throughout the state of Assam, covering an area of 15460.60 ha which constitutes 0.20 percent of the total geographical area of the state and 15.27 percent of the total area under wetlands. The smallest of them measures 5.0 ha while the largest one has 582.50 ha of areal coverage.

In Assam, a total of 1125 number of waterlogged areas are observed which are distributed unevenly covering an area of 23431.50 ha which constitutes 0.30 percent of the total geographical area of the state and 23.15 percent of the total area under wetlands. The smallest of them is 2.5 ha while the largest one has 3010.00 ha of areal coverage. These water-logged areas play significant role in the region’s economy as they are present in large numbers in the rural areas containing good amount of fishes and other aquatic fauna and providing habitat to a variety of migratory as well as domestic birds. Besides they have remarkable potential for supplying irrigation water to the nearby agricultural fields during the dry periods.

Swampy/Marshy areas :

These swampy/marshy areas constitute another major group of wetlands in Assam. These are identifiable on satellite imagery by their reddish tone indicating the presence of vegetation, associated with dark blue tone inferring to the presence of water and their occurrence in the low lying areas. Due to the presence of varied quantities of minerals in the water, these swampy/marshy areas are either moderately or highly turbid. In most cases, there is no feeder channel to control the inflow or outflow of water. In Assam, as many as 712 number of swampy/marshy areas have been identified from satellite data which cover an area of 43433.50 ha constituting 0.55 percent of the total geographical area of the state and 42.91 percent of the total area under wetlands.

Reservoirs :

Reservoirs are artificial impoundments of water for irrigation, flood control, municipal water supplies, hydro-electric power generation and so forth. There are as many as 10 number of reservoirs covering an area of 2662.5 ha which constitutes 0.03 percent of the total geographical area of the state and 2.63 percent of the total area under wetlands. The smallest of them covers 17.50 ha while the largest one has 930.00 ha of areal coverage. Majority of this type of wetlands contains water with low turbidity.

Tanks:

Assam has several thousands of family owned small size tanks, these have not entered into reckoning as far as this report is concerned because of the scale factor. In Assam, a total of 115 number of tanks are identified from satellite data. Majority of this type of wetlands have low turbidity. An analysis of aquatic vegetation in these tanks indicates that most of them are free from vegetation. Highest number of tanks are observed in Sibsagar district (20 number) followed by Kamrup (18 number) and Sonitpur (16 number). But area wise, the highest area under this category is observed in Sibsagar district (267.00 ha) followed by Sonitpur (83.50 ha) and Kamrup (80.00 ha) districts. Some of the important wetlands under this category are Gaurisagar Pukhuri, Sibsagar Pukhuri and Joysagar Pukhuri in Sibsagar district. Besides providing water to the people of the nearby areas, these tanks can also be used for rearing fishes and raising plantation crops like coconut, arecanut, cashewnut etc. along the sides of the ponds. Ornamental gardens can also be developed on the banks of the ponds. 

It is therefore felt to be an imperative need to conserve these wetlands and protect their unique biodiversity. If properly managed, the wetlands are going to be a source of immense wealth for this state leading also to enrichment of the quality of its environment.

NATIONAL WETLAND ATLAS: ASSAM

Source: State of Environment of Assam