Necessity of Regional Co-operation - The Ganga: Water Use in the Indian Subcontinent - page 263

discharge in dry season. Therefore, dams had to be constructed over a few of these
for irrigation and generation of hydro-electricity.
Thus, the total drainage area of the Ganga-Padma for a length of about 2,515 km
is about 1.03 million sq. km (their length within Bangladesh is about 380 km), out
of which 450,000 or 0.45 million, sq. km is on its north and 580,000 or 0.58 mil-
lion sq. km is on the south. Northern tributaries, like the Ghagra, the Gandak and the
Kosi together drain about 190000, or 0.19 million sq. km in Nepal (which is about
20% of the total drainage basin of the Ganga) and 30,000 sq. km in Bangladesh.
However, the total drainage area of the Ganga along the Bhagirathi-Hooghly for
a length of about 2,620 km up to the Sagar island is about 1.07 million sq. km,
out of which 430,000 sq. km is on the northern and eastern sides and the bal-
ance 640,000 sq. km is on the south and the west. Here, the northern and eastern
catchments include the areas of two small eastern tributaries - Jalangi and the
Mathabhanga (about 10,000 sq. km) and 60,000 sq. km from western tributaries
on the west.
The Brahmaputra
The Brahmaputra has its origin on the northern slope of the Himalayas in Tibet,
where it is called Tsan Po. It flows eastward for a length of about 1,430 km
(900 miles) along the foothills of the northern Himalayas and then turns south-
ward and enters Arunachal Pradesh, an Indian State at its north-easternmost point
and flows for about 180 km (110 miles). Then it turns west and flows through
other Indian State, namely, Assam - for about 650 km (400 miles) and then enters
Bangladesh. At the border, the river curves southward and continues on this course
for about 240 km (150 miles) to its confluence with the Ganga. After this, the com-
bined river flows for about 100 km (60 miles) and joins the Meghna. After about
another 240 km, the combined discharge joins the Bay of Bengal. The total length
of the river from source to sea is about 2,840 km (1,760 miles). Within Bangladesh,
the channel varies considerably in width, ranging from less than two to more than
15 km. The Brahmaputra is a braided channel, unlike the Ganga, basically a mean-
dering channel. During low flows, it becomes a multiple channel stream with sand
bars in between and the channels shifting back and forth, between the mainstream
banks which are often 6 to 12 km apart an aerial view of the river shows many chan-
nels, shoals and islands, which indicate a river of low hydraulic efficiency and of
heavy sediment load.
The discharge of the Brahmaputra is mostly derived from the snow-melt in Tibet
on the northern side of the Himalayas until it enters Arunachal Pradesh. Rainfall is
very heavy in Arunachal Pradesh, Assam and Meghalaya in India and in Dinajpur
and Mymensingh districts in Bangladesh, adding substantial flows in the river. The
reach between Dhubri where its leaves India and enters Bangladesh and Aricha
where it joins the Ganga is popularly known as Yamuna in Bangladesh. The old
Brahmaputra course which is now a distributary of the main river and joins the