The mighty Brahmaputra and effect of soil erosion in Assam

Sivasagar, Prangan Duarah: A common characteristic of fields of Assam is soil erosion. Highly productive and fertile soils of Assam are now facing serious problems like soil erosion. Since 1950, the problems like soil erosion and flood has devastated the rural economy of Assam in a greater extent. The mighty Brahmaputra is the major river of this region, which has wiped out nearly 4,000 square kilometers of the area at a rate of 80 square kilometers per year, destroying more than 2500 villages and affecting more than five million people in Assam. According to Assam’s Water Resources Department data 2010, Assam has 25 vulnerable and very severe erosion-prone sites and their survey estimated that the Assam valley portion of the Brahmaputra has lost approximately 7.4 percent of its land area due to river bank erosion and channel migration.

Photo: a sensitive issue of Assam: Soil erosion

7.4 percent! Is there any solution to control this soil erosion? It is high time to find the solution for this problem because the erosion problem is continuously causing the destruction of habitation and fertile land of Assam. For example only in Rohmoria, Dibrugarh District, more than 1,000 families have lost their habitation since last ten years and thousands of the Mising tribe is under threat due to heavy soil erosion in Assam’s Sumoi Mari village. This problem is also threatening our heritage Majuli continuously. The world’s largest inhabited riverine island and the seat of Assam’s neo-Vaishnavite movement, Majuli, cries in sorrow as the Brahmaputra washes away its land mass. Majuli’s once land area of 1250 sq km, is now reduced to 484.34 sq km. Likewise in Majuli and Dibrugarh district, a large number of families from other districts like Jorhat District, Matmora, Lakhimpur District, and Gakhirkhaitee, Koliabor, Nagaon District have become the victims of erosion of River Brahmaputra. The

worst situation of soil erosion are seen in Barpeta and Dhuburi district where no protection are seen till date and every years, 1000+ Hectors of land vanished on mighty Brahamputra.

It is found that the cause of soil erosion in Assam is more of natural effects like weak geological formation, active seismicity, high rainfall intensity etc. But the anthropogenic activities like the indiscriminate felling of trees, unscientific land use, and shifting cultivation have accelerated the process of soil erosion. The experts also pointed out that the rising of river bed due to sediment deposition makes the river extremely unstable and intense “braiding” a large water discharge. Thousands of people become victims of this cruel act of the mighty Brahmaputra. Imagine living when every single portion of your property is washed away by the river. Imagine the life of this people, whose everything is snatched away by the mighty Brahmaputra.

There is an immediate need for protection measures to protect our heritage, the world’s largest river island Majuli, to protect our Satras of Majuli- a rich cultural heritage, and to protect our land of old scripts and mask making the tradition. Don’t let it wash away our culture, our tradition, and our dignity.

Posted by on June 6, 2016. Filed under Editorial. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

One Response to The mighty Brahmaputra and effect of soil erosion in Assam

  1. Soil erosion is a process of detachment and transportation of soil by natural agencies of water and wind.

    Factors Influencing Soil Erosion:

    There are many factors which influence the process of soil erosion; these are discussed below:

    1. Rainfall:

    Precipitation is the most forceful factor causing erosion.

    Erosion is dependent on the amount, duration, intensity and frequency of rainfall. By the action of dashing rain drops on soil, soil granules are loosened, detached and separated into fine particles. Erosion is greater where the rainfall is not only heavy, but concentrated over short periods.

    2. Slope of Topography:

    The slope accelerates erosion as it increases the velocity of the flowing water.

    3. Vegetation:

    The vegetative cover protects the soil from the beating and dispersing action of the raindrops by forming a canopy over the soil surface. Vegetation also acts as a mechanical obstruction to flowing water, thus reducing its erosive potential. The plant roots help in building a better structure. They said in opening the soil and thereby accelerating water absorption and reducing surface run-off.

    4. Tillage:

    The infiltration and permeability of the soil is improved by the practice of proper tillage and thereby reducing the chances of erosion. But excess tilling exposes the soil to erosion, especially by wind.

    5. Nature of the Soil:

    Erodability of the soil is influenced by the nature of the soil, particularly its texture, structure, organic matter, amounts and kinds of salts present, presence of hard pan in the soil and presence of high water table.

    6. Soil Moisture:

    The presence of high water table checks the infiltration and permeability, thus allowing more flow of water on the surface, and greater erosion. At the same time, long continuous rainless periods cause loosening of soil and thus expose the soil to erosion by wind.

    7. Wind Velocity:

    Stronger winds have greater erosive potential, thus wind velocity is directly proportional to intensity of erosion.

    Types of Erosion by Water:

    Following are the types of soil erosion caused by water (Fig. 22.3).

    1. Splash Erosion:

    This type of erosion occurs when the falling raindrops splash on the soil, and beat the bare soil into flowing mud.

    2. Sheet Erosion:

    This occurs when soil is removed uniformly in a thin layer from the entire surface area. Movement of soil by splash erosion is the primary cause of sheet erosion.

    3. Rill Erosion:

    This type of erosion takes place when the run-off water, laden with soil flowing along the slopes, forms fingerlike channels. Rill erosion is an intermediate stage between sheet erosion and gulley erosion.

    4. Gully Erosion:

    As the volume of concentrated run-off increases and attains more velocity on slopes, it enlarges the rill into gullies. At an advanced stage, gullies result in ravines, which are sometimes 50 to 100 feet deep. In India ravines cover about 10 million hectares.

    5. Slip Erosion:

    Landslides cause slip erosion— big masses of soil and rock slip down, thus damaging the fields in the foothills and causing obstructions in communication. The effect of slip erosion is localised.

    6. Stream Bank Erosion:

    Streams and rivers change their courses by cutting one bank and depositing the silt loads on the others.

    During flash floods, the damage is much accelerated. The Kosi river in Bihar is reported to have changed its course westwards by 100 km within the last 100 years.

    7. Sea Shore Erosion:

    This type of erosion is caused by the striking action of strong waves.