Geography of Assam

Assam can be subdivided into three different Geographical regions:
(i)The Brahmaputra Valley or The Assam Valley.
(ii)The Barak Valley or The Cachar Plain.
(iii) Central Hill Region or Karbi Hills and North Cachar Hill Region.

(i) The Brahmaputra Valley:

With the Himalayan Range in the North, the Garo and Khasi-Jayantia Hills, the Karbi Hills and the Naga Hills, the Brahmaputra Valley resembling a rift valley, nestles within. Though the valley resembles a rift valley, it actually is a Ramp'e. The valley looks like a long corridor. It is the remnant of the Tethys sea of the bygone days and has a gradient from the east to the west. Through this flows the mighty Brahmaputra. A number of small rivulets flow into the Brahmaputra from both the northern and southern direction.

Among the main rivers flowing in the northern direction are the Krishnai and Dudhnai in Goalpara district; Kulsi, Bharalu and Digaru in Kamrup district; Kapili in Nagaon district; Dhansiri and Kakodonga in Golaghat district; Bhogdoi, Jan ji, Dikhow and Disang in Jorhat and Sivasagar districts; and the Buridihing in Dibrugarh district.

Among the rivers flowing in the southern direction are Sankosh, Gadadhar, Saralbhanga,and Champawati in Kokrajhar district; Manas and Ai in Bongaigaon and Borpeta district;Puthimari, and Pagladia, inNalbari and Kamrup district andBornadi and Jia Dhansiri inDarrang district; Panch Nai, JiaBharali Dikorai„ Borgang are inSonitpur and Darrang district. In Lakhimpur and Dhemaji districts Dikrong, Ranga Nadi, Subansiri and Jia Dhol are the rivulets, which flow through the two districts.

Subansiri, meaning the river of gold, is so called because there was once a time when people used to wash its sand and extract small pieces of gold from it. During the summer season, torrential downpour often causes the rivers in the north to swell in spate. The steep incline of the Himalayas makes the river rush into the valley flooding it and in the process these rivers frequently change their course. Due to these frequent changes and erratic flow of the river the local people have named these rivers as`pagla' meaning 'mad',e.g.,Pagladia, Jia Dhansiri, Jia Bhoroli, Bolia Dikrong etc.

Of the rivers named above, most form a boundary demarcating the different districts. Tourists visiting Assam who know about this demarcation can immediate!)identify which district they have entered. For example, the Son kosh river demarcates the State of West Bengal and Kokrajhar district of Assam; the Manas river demarcates Borpeta and Kokrajhar district; Puthimari river demarcates Nalbari and Kamrup district; Bor Nadi demarcates Kamrup and Darrang district; Panch Nal demarcates Darrang and Sonitpur district; Subansiri demarcates Lakhimpur and Dhemaji district; Buridihingdemarcates Dibrugarh andSivasagar district; Janji riverdemarcates Sivasagar and Jorhatdtstrict; Kakodonga demarcatesJorhat and Golaghat district;Kopili demarcates Karbi Anglongand North Cachar Hill districts.