brief introduction about kosi and their flood charecteristics

1. PRESENTED BY:-ABHISHEK VATS
18MTAESWC012

2.  Starts from northern slopes of Himalayas
inTibet,
 southern slopes in Nepal
 Crosses bihar from seven districts and meet
ganga in kursela in katihar district

3.  This river also called sapta kosi for its seven
upper tributaries
these are following
 the Sun Koshi, the Indravati River, the Bhote
Koshi, the Dudh Koshi, Arun River, Barun
River, and Tamur River.

5.  Tamur River with an area of
6,053 km2 (2,337 sq mi) in eastern
Nepal.(37%)
 Arun River with an area of
33,500 km2 (12,900 sq mi), most of which is
in Tibet(19%)
 Sun Koshi with an area of
4,285 km2 (1,654 sq mi) in Nepal and its
northern tributaries Dudh Koshi, Likhu Khola,
Tama Koshi, Bhote Koshi and Indravati.(44%)

8.  Between sunsari and saptari districts
 Constructed in 1958-1962
 56 gates
 Eastern embankment
 Western embankment

9.  Problem of flood
 Problem of river shifting
 Problem of heavy sediment load
 Problem of water logging and drainage
congestion.

12.  The Kosi’s alluvial fan has fertile soil and
abundant groundwater.
 The agricultural land in these areas is in great
demand.
 Too high population density

14.  Kosi River is notorious for the meandering
behaviour of its east-to-west course. It has a
very dynamic regime; very high sediment load
and frequent “avulasive shifts”.
 Between 1736 and 1953 the river moved
through a distance of about 112 Km.
westward.
 shifted by 20 kms to the west in the course of
single year.

16.  the bed slope of the river becomes as flat as
0.4 metre/km to 0.2 m per km.
 high sediment yield of 0.43 million
tonnes/year/km2.
 The average annual sediment load of the Kosi
has been assessed at 95 million cu.meter.

17.  in the process of shifting from east to west,
has left large tracts of low land and
undulating sandy tracts.

19.  Birpur barrage
 Jacketing the river with embankments

20.  Watershed management measures in the
upstream catchment.
 the construction of a large storage dam at
Chatra