The clouds that pass over this 1, m ridge along this belt, precipitate in the Brahmaputra valley, their intensity increasing towards the foothills of the Himalayas. The rainfall in the Brahmaputra valley ranges from 2, mm in Kamrup to about 4, mm in Tirap Division of the Arunachal. The Lanka area in Nagaon district on the north of the Khasi and Jaintia hillis lies in the rain shadow region and in consequence, the annual rainfall there is only about 1, mm.
The rainfall in the Tista valley varies from 1, mm in West Dinajpur district to 3, mm in Jalpaiguri district. During the winter season in January, the mean temperature over the catchment varies from The higher elevations in the Himalayan ranges experience lower temperatures.
During the summer season in April, the mean temperature in the lower part of the catchment varies from In the rainy season, in the month of July, the mean temperature varies from Towards the end of the monsoon season, in the month of October, the mean temperature over the basin varies from The Arunachal region experiences temperatures lower than Prior to independence, little thought was given towards water resources development in Brahmaputra valley.
For the low density of population in the sub-basin, the abundant rainfall and fertile soil could produce sufficient food grains to meet the requirements by traditional methods.
Most of the projects taken up and completed in the plan periods were medium and minor schemes. Dhansiri, Champamati and Teesta barrage are three major projects in the sub-basins. The Brahmaputra sub-basin has abundant hydropower potential. As per the latest assessment the hydropower potential of the basin is MW.. These schemes together amount for only Therefore, a large chunk of the hydropower potential of the basin remains to be tapped.
Guwahati, Shillong and Siliguri are the important urban centres. The sub-basin is rich in petroleum and coal. Digboi in Assam was the only source of petroleum in India until about Petroleum products, jute, drugs and pharmaceuticals are other industries in the sub-basin.
Hydrological observations in the sub-basin are carried out by the Central and State Governments. The Central Water Commission maintains H. O sites in the basin. In addition, gauge data at 80 sites, gauge-discharge data at 15 sites and gauge, discharge and sediment data at 25 sites, maintained by the State Governments and the Brahmaputra Board, are also available.
The Central Water Commission operates 27 flood forecasting stations in the sub-basin. Brahmaputra Board was established by the Govt. The Board has jurisdiction over the adjacent Barak valley also.
Floods, erosion and drainage congestion are the main problems of the valley. As mentioned above, the Brahmaputra Board has been set up to look into these problems. WRIS publications. Notice how the narrow channel widens after passing the town of Pasighat, transforming into a braided river with multiple, interlacing channels. As the water slows in the flatter Brahmaputra Valley, it loses its capacity to carry sediment, depositing the excess silt in sandbars. In the course of a few kilometers, the river channel increases its width twentyfold.
In some ways, the sediment is a blessing. Annual floods spread mineral-rich silt across farmland adjacent to the river, replenishing the soil. In other ways, it poses challenges. There is so much of it that large boats are unable to navigate many parts of the river.
It flows southeast and falls into the Brahmaputra. The major part of the river lies within India. The Old Brahmaputra takes off from the left bank of the Brahmaputra or the Jamuna to the north of Bahadurabad. Flowing more or less southeast it passes by [[Jamalpur District jamalpur]] and mymensingh towns and falls into the Meghna at Bhairab Bazaar. The river has no tributary coming from the northeast. Several small distributaries, viz, bangshi , banar , Sirkali and Satia, however, flow out from it.
The Bangshi runs more or less south to join the turag and together fall into the buriganga near Dhaka. The Banar, Sirkali and Satia converge to flow together as the shitalakshya and meet the Dhaleshwari close to munshiganj. The Karatoya is the longest and largest tributary of the Jamuna and originates in a marsh in Baikunthapur in Jalpaiguri district of India.
It receives a number of tributaries on the Indian side. It was formerly the main channel of the Tista and was perhaps a distributary of the Brahmaputra. The Karatoya changes its name to atrai from khansama upazila and crosses the barind tract lengthwise all the way to fall into the baral that connects the Ganges with the Jamuna at bera upazila of pabna district.
The part of the Karatoya that passes through Rangpur carries very little water and falls into the Bangali river. The Bogra-Karatoya rises from mithapukur , flows past bogra town and meets the Bangali that links the Rangpur-Karatoya with the Bogra-Karatoya.
The Dinajpur-Karatoya was connected with the Rangpur-Karatoya north of Khansama, but at present very little water passes down that channel. The Jamuneshwari-Karatoya flows in slight meanders south-southeast to gobindaganj upazila where the main stream turns east through the Katakhali and falls into the Bangali.
The portion of the former river that runs through shibganj upazila remains dry most of the year and effectively separates the Rangpur-Karatoya from the Bogra-Karatoya. The latter flows past Bogra town and runs south, till it joins the Bangali to make the Phuljhor river, which falls into hurasagar.
The most severe earthquakes with Richter magnitude 8. The latter one particularly had severe impacts on the river Brahmaputra. As a result of this earthquake river bed was raised at least by three meters at Dibrugarh which had increased the flood and erosion intensity of the river. The Brahmaputra in its path from snow covered mountains of Himalaya to the deltaic flood plains of Bangladesh covers different climatic regimes.
The mean annual rainfall in the Brahmaputra basin excluding the Tibetan portion is mm. The distribution of rainfall is different at different parts of the basin.
In the southern slopes of Himalaya the rainfall is over mm but in parts of Nagaland this is mm. In this basin, areas which are above or equal to the elevation of m experience snowfall. In the Indian part of Brahmaputra basin there are glaciers which covers an area of Out of these glaciers are in Teesta basin and glaciers are in Arunachal. Climate change will also impact the rainfall and snowfall pattern in the Brahmaputra basin. This issue needs more serious attention and we will come up with more detailed blogs on this.
The Brahmaputra river basin hosts very rich and unique bio-diversity. The whole of northeastern region is a globally recognized bio-diversity hot spot. In the Indian territory the total forest cover of the Brahmaputra basin is 1,14, sq. In the distribution of forest cover among 6 states in Brahmaputra basin, Arunachal Pradesh tops the list with The tally of rest of the five states is as follows — Nagaland Besides, the aquatic bio-diversity of the Brahmaputra and its tributaries is also very rich.
Brahmaputra river basin is known to be very prone to flood and erosion and these two hazards have led to many problems in the basin. In India, out of the eight northeastern states, Assam faces the most severe brunt of flood and erosion. Both flood erosion has been severely affecting the economy as well political, social and cultural milieu of Assam.
Experts opine that natural as well anthropogenic factors lead to devastating floods in northeastern region. Along with floods, erosion is also threatening the lives of the people in the state of Assam as it leads to permanent loss of land.
Here we can take the case of the river island Majuli, which had been one of the worst sufferers of the erosion done by Brahmaputra.
In the total area of Majuli was sq km but it has now reduced to 3. In Bangladesh the Brahmaputra river which known as Jamuna is also infamous for severe floods and erosion. The river carries huge water and sediment discharge in this deltaic region. Because of its geographical setting, Bangladesh is very much dependent on its river for fertile fields and diverse flora and aqua culture but rivers also brings several hazards in the form of floods and erosion. Bangladesh has witnessed severe annual floods but the floods in , , and were the most severe ones in recent decades.
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