Editing Brahmaputra River (section)

===Channel morphology===
The course of the Brahmaputra River has changed dramatically over the past 250 years, with evidence of large-scale avulsion, in the period 1776–1850, of {{Convert|80|km|abbr=on}} from east of the Madhupur tract to the west of it. Prior to 1843, the Brahmaputra flowed within the channel now termed the [[Old Brahmaputra River|"Old Brahmaputra"]]. The banks of the river are mostly weakly cohesive sand and silts, which usually erodes through large scale slab failure, where previously deposited materials undergo scour and bank erosion during flood periods. Presently, the river's erosion rate has decreased to {{cvt|30|m|abbr=on}} per year as compared to {{cvt|150|m|abbr=on}} per year from 1973 to 1992. This erosion has, however, destroyed so much land that it has caused 0.7 million people to become homeless due to loss of land.

Several studies have discussed the reasons for the avulsion of the river into its present course, and have suggested a number of reasons including tectonic activity, switches in the upstream course of the Teesta River, the influence of increased discharge, catastrophic floods and river capture into an old river course. From an analysis of maps of the river between 1776 and 1843, it was concluded in a study that the river avulsion was more likely gradual than catastrophic and sudden, and may have been generated by bank erosion, perhaps around a large mid-channel bar, causing a diversion of the channel into the existing floodplain channel.

The Brahmaputra channel is governed by the peak and low flow periods during which its bed undergoes tremendous modification. The Brahmaputra's bank line migration is inconsistent with time. The Brahmaputra river bed has widened significantly since 1916 and appears to be shifting more towards the south than towards the north. Together with the contemporary slow migration of the river, the left bank is being eroded away faster than the right bank.<ref name="researchgate.net">{{Cite journal | url=https://www.researchgate.net/publication/268404868 | title=Channel and Bed Morphology of a Part of the Brahmaputra River in Assam| journal=Journal of the Geological Society of India| volume=62| date=August 2003| last1=Gilfellon| first1=George| last2=Sarma| first2=Jogendra| last3=Gohain| first3=K.}}</ref>

==== River engineering ====
The Brahmaputra River experiences high levels of [[bank erosion]] (usually via slab failure) and [[River channel migration|channel migration]] caused by its strong current, lack of riverbank vegetation, and loose sand and silt which compose its banks. It is thus difficult to build permanent structures on the river, and protective structures designed to limit the river's erosional effects often face numerous issues during and after construction. In fact, a 2004 report<ref>{{Cite report
| date = 2004
| url = http://reliefweb.int/sites/reliefweb.int/files/resources/0601496727BB568AC1256F230033FBC5-lcg-bang-6oct.pdf
| title = Monsoon Floods 2004: Post Flood Needs Assessment Summary Report
| journal = Bangladesh Disaster and Emergency Sub-Group 
| location = Dhaka, Bangladesh
| page = 23
| access-date = 25 February 2016
| archive-url = https://web.archive.org/web/20160321070102/http://reliefweb.int/sites/reliefweb.int/files/resources/0601496727BB568AC1256F230033FBC5-lcg-bang-6oct.pdf
| archive-date = 21 March 2016
| url-status = live
}}</ref> by the Bangladesh Disaster and Emergency Sub-Group (BDER) has stated that several of such protective systems have 'just failed'. However, some progress has been made in the form of construction works which stabilize sections of the river, albeit with the need for heavy maintenance. The [[Bangabandhu Bridge]], the only bridge to span the river's major distributary, the [[Jamuna River (Bangladesh)|Jamuna]], was thus opened in June 1998. Constructed at a narrow braid belt of the river, it is {{Convert|4.8|km|abbr=on}} long with a platform {{Convert|18.5|m|abbr=on}} wide, and it is used to carry railroad traffic as well as gas, power and telecommunication lines. Due to the variable nature of the river, the prediction of the river's future course is crucial in planning upstream engineering to prevent flooding on the bridge.

China had built the [[Zangmu Dam]] in the upper course of the Brahmaputra River in the Tibet region and it was operationalised on 13 October 2015.<ref>{{cite news |date=13 October 2015 |title=China operationalizes biggest dam on Brahmaputra in Tibet |url=http://timesofindia.indiatimes.com/world/china/China-operationalizes-biggest-dam-on-Brahmaputra-in-Tibet/articleshow/49335741.cms |newspaper=The Times of India |access-date=26 July 2016 |archive-url=https://web.archive.org/web/20160422074545/http://timesofindia.indiatimes.com/world/china/China-operationalizes-biggest-dam-on-Brahmaputra-in-Tibet/articleshow/49335741.cms |archive-date=22 April 2016 |url-status=live }}</ref>