4. The Indian rivers can be classified into four
major groups:-
1. Himalayan Rivers
2. Rivers on the central high lands
3. Rivers on peninsula
4. Rivers on the coasts
5. Three important rivers Himalayan rivers are
Indus, Ganga and Brahmaputra.
These rivers flows in the north west region.
This region covers the states like Jammu-
Kashmir, Punjab, Haryana, Rajasthan and the
parts of Himachal Pradesh.
6. The Ganga region covers the states of
Uttarakhand, U.P., Bihar, Himachal Pradesh,
West Bengal and Delhi.
The main flood problem in these region bring
a lot of sediments, overspill their banks and
change their course,
7. Brahmaputra is known for its huge and
disastrous floods.
It covers Assam, West Bengal, Tripura,
Manipur, Nagaland etc.
It is also called as the ‘the tears of Assam’.
8. It consists of Mewar high land, Bundelkhand
plateau, Malwa plateau etc. These hifhlands
gives he rise to the rivers like Narmada, Tapi,
Sabarmati, Mahi, Mahanadi.
The floods in the river Narmada causes the
damage to the property and life of Bharuch
district in Gujarat.
The floods in the Tapi cause the widespread
damage to the Surat.
9. Most of the peninsular rivers rise on the
western ghats and flows towards the east to
meet the Bay of Bengal.
River Godavari, Krishna, Kaveri, Koyana all
non perenial rivers.
The region as a whole does not havea serious
flood problems, except that on some rivers of
Orrissa state
10. The rivers which originates on the western
Ghats and flows toward west are called
coastal rivers.
These are kali vasistha in Maharatstra,
Mandwi and zuari in Goa.
These rivers are short in length and have to
run over the steep slopes so have fast runoff.
11. 1. Intense Rainfall
2. Topography of the catchment
3. Sedimentation of rivers and reservoirs
4. Obstruction in the river flow
5. Failure of the dam
6. Failure of the river embankment
7. Inadequate cross drainage work
8. Contraction of waterway
12. The flood occurs because of heavy rains or
melting of snow when discharge in the river is
so high that its natural cross section is unable
to contain it.
Flood control is require to reduce the flood
damage.
Flood control is also known as flood
management.
13. There are two types of measures to mitigate
the flood disaster:
1. Structural mitigation
2. Non-structural mitigation
14. The structural mitigation measures are:-
1. Storage reservoirs
2. Levees
3. Flood walls
4. Channel improvement works
5. Diversion of flood water to flood ways
6. Construction of high earth platform
7. Sluices
15. A levees is an earth embankment .
It is sort of an earthen dam constructed along
the river.
The construction of levees is more common
than flood walls as it is more economical and
convinent.
18. i. They are easy to construct parallel to the
river banks by available earth.
ii. Initial cost of construction is less.
iii. They prevent overflowing the banks.
iv. Maintenance is easy
v. It increases the storage capacity of the river
19. When embankments fails during the high
stage of the flood it suddenly creates
catastrophic flood exactly like dam break.
During flood time round the clock
maintenance is very mush essential against
failure.
Due to the increase of river capacity velocity
decreases also the depth of the river
decreases with the time.
20. Flood walls are used in the developed area
where it is difficult to obtain enough land for
the construction of levees.
A flood wall is a sort of gravity dam
constructed along the river.
Flood walls are designed to withstand the
uplift pressure like gravity dams.
