Floods are a major problem in India, affecting over 40 million hectares or 12% of the country's land area. This seminar discusses the causes of floods, their impacts, flood-prone areas in India, methods for selecting a design flood, and techniques for flood control including reservoirs, levees, flood walls, river channel improvements, floodways, watershed management, cutoff channels, and flood plain zoning. The key methods for flood control are reservoirs to store floodwater, levees and flood walls to contain floods, and improving river channels to increase conveyance of flood flows.

1. SEMINAR
ON
FLOOD CONTROL
Seminar guided by
Dr. ANIL K. MATHUR
Professor
Submitted by
SANDEEP KUMAR
CRN. 12/571

2. CONTENTS
1. Introduction
2. Causes of flood
3. Flood impacts
4. Indian flood prone areas
5. Selection of design flood
6. Method of flood control
7. Procedure for design of flood control project
8. Conclusions

3. INTRODUCTION
 A flood is a relatively high stage of the river which is
usually accompanied by overtopping of the natural
banks of the river in a particular reach.
 In India about 40 Mha of land is flood prone, which
is 12% of the total geographical area of 328 Mha.
About 12Mha of the flood prone land has been
provided with some reasonable protection against
floods by providing flood embankments, drainage
channels, etc.
 In 1976 Rashtriya Barh Ayog or National Flood
Commission, was set up by Government of India to
study the flood problem.

4. CAUSES OF FLOOD
1. High rainfall
2. Failure of hydraulic structure
3. Snowmelt
4. Coastal flooding
5. Deforestation
6. Poor farming
7. Overgrazing
8. Overcultivation
9. Poor water management
10. Population pressure

5. FLOOD IMPACTS
1. Tangible loss: Loss can be estimated in terms of money value.
 Personal properties like building, materials etc.
 Loss of crops
 Loss due to disruption of business
 Loss due to disruption of road and railways
2. Intangible loss: Loss can't be estimated in money values.
 Human loss
 Disruption of Air / Train / Bus services
 Spread of Water-borne Communicable Diseases
 Communication Breakdown
 Electricity Supply Cut off
 Social Disruption
 Increase in Air / Water Pollution

6. INDIAN FLOOD PRONE AREAS
The rivers in India can be broadly divided into
the following four regions for a study of flood
problems:
1. Brahmaputra River Region
2. Ganga River Region
3. Northwest River Region
4. Central India and Deccan Region

7. INDIAN FLOOD PRONE AREAS(CONT.)
OTHER
STATES
43.9%
BIHAR
12.71%
UTTAR PRADESH
21.90%
ASSAM
9.40%
WEST BENGAL
7.91% ORISSA
4.18%

8. SELECTION OF DESIGN FLOOD
1. PROBABLE MAXIMUM FLOOD (PMF)
2. STANDARD PROJECT FLOOD
3. FLOOD CORRESPONDING TO A CERTAIN
DESIRED FREQUENCY
ESTIMATION OF DESIGN FLOOD
1. Maximum observed flood method
2. Empirical flood formula method
3. Enveloping curves method
4. Unit hydrograph method
5. Frequency analysis method

9. METHOD OF FLOOD CONTROL
1. Reservoirs
2. Levees
3. Flood walls
4. Improvement of river channel
5. Diversion of flood water to flood ways
6. Watershed management for flood control
7. Construction of cut-off
8. Flood plain management
9. Afforestation
10. Flood forecasting

10. FLOOD CONTROL RESERVOIR
A flood control reservoir, generally called a
flood-mitigation reservoir, stores a portions of
the flood flows in such a way as to minimize the
flood peaks at the areas to be protected
downstream.
There are two basic types of flood mitigation
reservoirs;
(1). Detention reservoir
(2). Retarding reservoir

11. FLOOD CONTROL RESERVOIR(CONT.)
Detention
reservoir:
A reservoir
having gates and
valves installation at
its spillway and at its
sluice outlets is
known as detention
reservoir.

12. FLOOD CONTROL RESERVOIR(CONT.)
Retarding
reservoir
A reservoir with
uncontrolled and
ungated outlets is
known as a
retarding basin or
retarding
reservoirs.

13. LEVEES
Levee cross section must be
adjusted to fit the site and
available materials.
Minimum top width 3 m
usually recommended.
River side protected by stone
pitching and contrary side
protected by turfing.
Generally, levees run along
river bank with a margin of 2
m between toe of levee and
top of river bank.
Sometimes, it may run some
distance away from river
bank.

14. FLOOD WALLS
Flood wall is usually of
masonry or concrete.
Usually constructed in
which enough land is not
available for levees.
If land is costly or
limited, it is more
economical to construct
flood wall.
Constructed on river
bank.
Proper foundation should
be provided and precaution
should be taken against
scouring.

15. IMPROVEMENT OF RIVER CHANNEL
 Increase the discharge or velocity of stream or to
decrease the stage and duration of flood.
 Increase in size of cross section by widening and
excavating stream bed.
 Increasing velocity by smoothing river bed.
 Realignment of the river.

16. FLOOD WAYS
 Low lying areas along the course of the river are
known as floodways.
 Depression into which a portion of the flood
water diverted from a river through natural or
artificial channel for temporarily storing.
 After flood recedes, the store water is permitted
to flow back to river.
 Floodways used during periods of major floods,
land can be used for agricultural purpose.

17. WATERSHED MANAGEMENT FOR
FLOOD CONTROL
 Providing vegetal cover.
 Conservation of water in agriculture.
 Creation of farm ponds.
 Use of cover crops

18. CONSTRUCTION OF CUT-OFF
During heavy rainfall
when large flood
discharge approaches
the sharp bend of the
river, it overflows its
bank and submerges
the surrounding area.
So cut-off constructed
to reduce travel time
and water flow with
high velocity along a
straight path.

19. FLOOD PLAIN MANAGEMENT
 An important non-structural measure.
 Regulates land use in flood plains to restrict damage by floods.
 Involves demarcation of zones in flood plains compatible with
flood risks involved.

20. FLOOD PLAIN ZONING
WATER SUPPLY
FACTORY
POWER HOUSE
UNIVERSITYRESIDENTIAL AREA
GOVT. OFFICE
HOSPITAL
NORMAL CHANNEL
PARK
FREQUENT FLOOD
FLOOD ONCE IN 25 YEARS
FLOOD ONCE IN 100 YEARS
III IIII III I
I

21. AFFORESTATION
 They hold the shores and keep the river bed in
place and in shape. This helps the water flush
away reducing the length of the flood.
 They serve as a "filter" for floating objects (such
as rocks, trees and debries), that are a major
threat during floods because they crush on
house and infrastructure.
 They slow down the water reducing flood
energy and therefore, the threat for people and
buildings.

22. FLOOD FORECASTING AND WARNING
PRESENT SYSTEM - SCHEMATIC DIAGRAM
WEATHER FORECASTS
RIVER STAGE &
DISCHARGE AT
BASE STATION
RIVER STAGE &
DISCHARGE AT
FORECASTING STATIONS RAINFALL
F.M. O. OF I.M.DFLOOD FORECASTING
CENTRES & CONTROL
ROOMS
FORMULATION OF
FORECAST
C.E., S.E.
STATE GOVT.
CONTROL ROOM
PRESS RADIO
P & T
POLICE FLOOD
COMMITTEE
CIVIL AUTHORITIES
ENGG. AUTHORITIES
DEFENCE
RAILWAYS
INDUSTRIES
F.M.O OF I.M.D
REGIONAL OFFICES
OF I.M.D.
REGIONAL OFFICES
OF I.M.D.
DOORDARSHAN
CWC HQ MINISTRY OF WR

23. PROCEDURE FOR DESIGN OF FLOOD
CONTROL PROJECT
 Estimate the project design flood and determine the flood
characteristics of the area.
 Identify the areas to be protected by the project.
 Conduct a field survey to determine the flood damages which are
likely to occur corresponding to different stages of flood.
 Identify suitable methods of flood control. Select suitable sites for
different works and determine the physical characteristics and
topography of these sites.
 Design the flood control works for different alternatives of flood
control measures so that the cost estimates may be made and
their effects on the flood discharge may be estimated.
 Select the flood control measures or a combination of measures,
which offer the desired protection at a minimum cost.
 Perform the economic analysis of the benefits and costs to
determine whether the selected project is economically viable.
 Write the project report giving the details of the possibilities
explored, the recommended measures and the expected degree
of protection.

24. CONCLUSIONS
 Flood can not be absolutely controlled, flood can only be managed to
reduce flood losses.
 An increase in channel conveyance provides flood control by allowing
flood waves to pass more freely downstream.
 Levees create a physical barrier to contain flood water and protect the
flood plain from being flooded.
 Reservoirs attenuate flood waves through providing flood water storage.
 Flood ways provide flood wave attenuation through diversion away
from the river.