Assam a state in the northeast region of India is a unique geographical entity presenting a rich physical and cultural diversity. The state's natural landscape is changing fast with the growth of industrialization and urbanization and especially the ever-increasing inflow of people from within and outside the country.
Assam is located in the tropical latitude 24.30 N and 280 N and eastern
longitudes 89.50 E and 96.10 E. surrounded on three sides
by hills and mountains. Assam is bounded to the north by the kingdom of Bhutan
and the state of Arunachal Pradesh, to the east by the states of Nagaland and
Manipur, to the south by the states of Mizoram and Tripura, and to the west by
Bangladesh and the states of Meghalaya and West Bengal.
The
state of Assam is comprised of three physiographical divisions, namely, the Brahmaputra
Valley, the Barak Valley, the Karbi-Anglong, and the
North-Cachar hills. The Brahmaputra Valley, which forms the northern part, is the
largest in size comprising 71.7 % of the total geographical area of the state. On
the other hand, the Barak Valley region which forms the southern part is comparatively
smaller in size. The two Valleys derived their names from the respective main
rivers, the Brahmaputra and the Barak flowing from East to West in the
Valleys. The hill regions formed by the Karbi-Anglong and the North-Cachar
hills stand separated into the two valleys from the middle.
Physiographical Divisions of Assam
The Brahmaputra Valley
Brahmaputra
Valley is situated in Assam, the frontier province of India on the extreme
northeast. Assam is located between 24°8’ to 27°56 north latitudes and 89°41 ’
to 96°02 East longitudes. The
area of the Brahmaputra Valley is 54,315 square Kilometers. The Valley of Brahmaputra is surrounded by the Arunachal Himalaya in the North, Patkai, and Arunachal
hills in the East, and Naga Hills, Karbi, and Meghalaya Plateau in the South. Its
western side is open and joined to the Ganga plain.
The
Brahmaputra Valley is an alluvial plain it about 720 Km wide from northeast to west and an average of 90 Km wide from north to south. The Brahmaputra is one of the
largest and youngest rivers in the world. It flows majestically through the
heart of Brahmaputra Valley. The total length of the Brahmaputra River is about
2,897 Kilometres and its drainage area measures about 9, 35, 504 Square
kilometers. Its flows for about 724 Kilometres down the Assam Valley. It is
navigable all year. In monsoon, it grows like a sea.
The Brahmaputra
divides its Valley into three geographical areas called the Uttarkol or North Bank,
Dakhinkol or the South bank, and the Majuli, or the largest riverine island in the
middle. After crossing the State of Assam the river turns south, flowing through
Bangladesh and joining with the Padma River, it flows as Meghna and falls into
the Bay of Bengal. It is on the bank of this river the civilization of Assam grows.
So the history of Assam is indeed the history of the civilization of the Brahmaputra
Valley. The Valley of Brahmaputra is spreading flat and wide, from east to west
in the lower portion to projecting northward in its upper part where it tapers
off.
The
mighty Brahmaputra with its innumerable tributaries (Buridihing in Dibrugarh district;
Disang, Dikhaw, Bhogdoi, Jhanji, and Dhansiri in Sibsagar district; Subansiri in
Lakhimpur district, Kapil i in Nagaon district and Bharali and Barnadi in Darrang
district; Pagladia, Beki, Manas, Digaru, Kulsi in Kamrup district; Sankosh,
Krishnai, Soralbhanga, Champamati in Goalpara district) from either side make
up the total drainage system of the valley.
Depending
upon the topography, Physiography, various climatic conditions, and the cropping
pattern, the Brahmaputra valley itself can be divided into k Zones, viz., upper
Brahmaputra valley, central Brahmaputra valley, north bank plains, and the lower
Brahmaputra valley.
Upper Brahmaputra Valley:
It consists of Dibrugarh and Sibsagar districts, including Majuli Island.
The area slopes down gradually from the hills of the Arunachal Pradesh, Nagaland, and Karbi Anglong districts. The upper slopes are very suitable for tea
plantations.
Central Brahmaputra Valley:
In the central Brahmaputra valley region, lies the Nagaon district. It is situated
on the south bank of the Brahmaputra and on the west of the upper Brahmaputra valley,
which alone is considered a distinct region. The district is encircled by hills
of the Shillong plateau on the east, west, and south; and on the north lies the
mighty Brahmaputra.
Numerous
isolated hillocks are found lying scattered and even along the Brahmaputra bank,
which are in fact outliers of the Shillong plateau. Thus the northern boundary
of the district is for the most part higher than the central p la in s of the
region which has an appearance of being encircled by hills on all sides.
Due to the
physiographic condition, Nagaon district is frequently inundated by floods during
the rainy season. Tall grasses are found to grow abundantly along the bank of
the Brahmaputra and especially in the northeastern part. The world-famous
Kaziranga wildlife sanctuary constitutes such a part of the Nagaon district while the other parts are constituted a part of the Sibsagar district.
North Bank Plain region:
On the northern bank of the river Brahmaputra, there lies a distinct region comprising
of Lakhimpur and Darrang districts. Physiographically, the entire region can be
divided into 3 small parallel belts.
The foothills proper, with alluvial soil structure, is under deep forest. There are
small tea estates extending from the Subansiri river to the Barnadi. The
central belt is a narrow one having alluvial soil and is suitable mainly for
rice cultivation. The low-lying belt which includes the area on the edge of the
Brahmaputra, the area between the river Subansiri district is inundated by
floods almost every year.
The Lower Brahmaputra Valley region:
The lower Brahmaputra valley region consists of Kamrup and Goalpara districts
which form the lower Assam plains. There lie the folded ranges of the Himalayas
on the north side and the Shillong plateau on the south. The entire area on the
southern side of the Brahmaputra is belted with spurs of the plateau.
As a
matter of fact, some of the outlines of the plateau are found even on the north
bank of Brahmaputra. The northern foothills are covered by critically dense
forests and tall grasses. Valuable timber trees like 'Sal' and ’Teak' grow
abundantly on the foothills of the southern part. The central portion of the
lower Brahmaputra valley region is famous for the cultivation of rice.
The Barak Valley
The
Barak Valley region has an undulating topography characterized by hills,
hillocks (locally known dllah), wide plains, and low-lying waterlogged areas
(locally called beels). Most of the hills have a North-South spread
interspersed by strips of plains. The region is flanked by the Southern belt of the Barail range with an average width of 6 or 7 miles containing peaks between 3
and 6 thousand feet in height, on the Eastern frontier, lay the Bhuban range, a
continuation of the Lusai hills.
The
hills divisions consisting mainly of the Barail range from Jaintia hills to a
point little to the west of the Asalu range formed a continuous wall of mountains
gradually increasing in height towards the East. The hill range entered Barak
Valley at the place known as Kalangtam at which the hills become 4336 feet
above the level the sea.
Most of
these hills were rugged and precipitous into which innumerable rivers cut deep
gorges as they descended upon the plains. The mountainous character of the
region rendered inters communication extremely difficult.
Physiographically,
the plain areas of the region can be divided into four classes, namely
Undulating plains, Broad meander plains, Flood plains, and low-lying areas. The
Undulating plain areas are scattered across the region and mixed with low hills and
meander plains. Barak River in large patches mixed with low hills and
piedmonts. The Flood plains area chiefly covers the banks of the Barak River.
While the low-lying areas consisted of natural depressions and waterlogged
areas. These are scattered in all three districts and occur mainly in
the south of the Barak river.
The principal river of the region namely the “Barak” took its rise a little to the
west of Maothana, on the northern boundary of Manipur. Taking a southwest
turn from its source near Tipaimukh in Manipur, it then comes to the north and for
considerable distances forms the boundary line between the region and the state of Manipur.
After
its junction with the river Jiri, this too for a considerable area formed the
border between the Barak Valley region and the Manipur. At Jiribun it turned again
to the west and flowed to the heart of the Cachar district of the region and
reached Badarpur town in the Karimganj district. From Badarpur to Haritikar, it
provided the boundary between the Karimganj district and Bangladesh. At
Flaritikar, the river became divided into two branches, namely, Surma and
Kushiara.
The
later branch entered Bangladesh while the former entered Karimganj town and
continue to form the frontier of the Barak Valley region with Bangladesh. In
addition to Jiri, the Barak river received numerous tributaries from the hills
like Chiri, Barail, Madhura, Jatinga, Dalu, etc.
The other principal rivers of the region are Sonai, Daleswari, Katakhal, Longai, Singla and Kakra. Most of these rivers were dried up during winter and due to deposits of silt, the drainage capacity becomes ineffective. The rivers would remain unavailable even in the rainy season. As such in summer all these rivers rise up in high spate causing high floods visiting every year in the region.
The Karbi Anglong and North Cachar Hills
The
Hills in Karbi Anglong is part of the Shillong plateau having an elevation of 300
to 400 meters with a moderate slope. The highest peak in this region is 1,360
meters high, the ‘Singhason’ peak located in East Karbi Anglong. More than 80%
of the geographical area is steep to moderate slope, with a hilly land surface, and
undulating plains. The average altitude is 300-400m above MSL. West Karbi
Anglong is dominated by steeper slopes except towards the extreme east. Whereas the northern part of East Karbi Anglong is steeper but the slope becomes gentle
towards the south.
Physiographically, the district of Karbi-Anglong can be divided into the following two distinct divisions:
- The Plain Area which consists of valleys of Jamuna, Kapili, and Dhansiri rivers bordering the districts of Nagaon and Golaghat,
- The Hill Area covers 85% of the geographical area.
Plains:
It covers 40% area of Karbi Anglong (4,132.8 sq. km). The area located between the northern and the southern hills is the Diphu sub-division which is characterized by undulating plains of subdued relief. The minor streams include Kaliani, Barpani, Patradisa, and Dikharu. The plain area of Karbi Anglong covers mainly Howraghat, Bokalia, Balipathar, and Bokajan areas. These plains are mainly formed by the rivers of Jamuna, Kapili, and Dhansiri. Hills with Gentle Slope: This area comprises 60% of the Karbi Anglong district. A slope of 15-40 percent steepness is considered a gentle slope. A negligible area of the N.C. Hills bordering Karbi Anglong and Nagaon district falls under this category.
Hills with Steep Slope:
Comprises the hill tracts of the N.C. Hills covering 4156.5 sq. km. The hills with 40-80 percent slope come under this category