The document discusses methods for flood control, including controlling water levels through dams and check dams, building barriers like levees and flood walls, altering river channels by straightening or widening them, controlling land use around rivers, and using floodways. It provides details on reservoirs, levees, and floodways as specific flood control techniques. Levees are described as earthen embankments built between rivers and protected areas to restrict flood water flow, with considerations for their height and freeboard. The Mississippi River levee system is highlighted as one of the largest in the world.

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GUJARATTECHNOLOGICALUNIVERSITY
BIRLA VISHVAKARMA MAHAVIDYALAYA
Subject :- Hydrology And Water Resources Engineering
Year : 3rd (5th sem-Civil)
Methods of flood control
Compiled by:- Jora Hitesh .H
En no:- 140073106009
Guided by : Prof. Reshma Shah
Prof. Pitroda Sir

2. Causes of flooding
• Monsoon rain
• Urbanization increases surface run-off
• Dam collapse
• Tsunami caused by underwater earthquake
• Snow melt
• Global warming
• Deforestation
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To control flooding…..
1. Control the water level
dams
check dams
2. Build barriers(Levees)
embankments
flood walls
3. Alter the river’s channel
Straighten it
Widen and deepen it
4. Control land use around the river (land use zoning)
5. Floodways

4. 1. Control the water level
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5. Reservoirs (dams)
• Reservoirs are one of the most direct methods of flood
control through storing surface runoff; thus,
attenuating flood waves and storing flood water to be
redistributed without exceed in downstream flood
conditions.
 For flood control, it is ideal to maintain the reservoir
at the lowest level possible for storage. On the other
hand, keeping the reservoir at a high level provides the
ability to maintain low flows and hydropower
production in droughts.
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2.Build barriers(levees)

7. Levees
 Levees are one of the oldest forms of river flood
control used to protect people and their property from
damaging flood waters.
 They consist of earthen embankments built between
the river and the area to be protected.
 Levees restrict the flood water’s flow to the river side
of the levee. This will increase the stage in the river.
 Levees should be built well outside the meande width
of river’s prone to lateral migration.
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8. Levees
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 The elevation of the levee crest is determined through
careful consideration of many factors:
 Cost risk analysis of the cost to build the larger levee
versus the risk of damage brought on by a larger flood.
 Political, social, military, and environmental reasons
will all play a part in determining a levee’s design
height.
 The cost to double the size of a levee is most often
correlated to the square of the material needed. This
means the cost can be quite high and often prohibit
increased levee design elevations.

9. Freeboard should be taken into account when sizing a
levee:
2 ft. for agricultural levees
3 ft. for urban levees
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10. The Mississippi River levee system represents one
of the largest such systems found anywhere in the
world. They comprise over 3,500 miles (5,600 km)
of levees extending some 1,000 miles (1,600 km)
along the Mississippi. They average 24 feet (7 m) in
height; some Mississippi levees are as much as 50
feet (15 m) high.

11. 3. Alter the river’s channel
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4. Control land use

13. Floodways
 As defined in River Mechanics, floodways are
dedicated pathways to divert floodwaters into a
topographical depression near the river or into another
large
 Entrance is controlled by hydraulic structures near the
floodplain to capture overbank floodwaters.
 Sedimentation and scour must be considered in
floodway operation and design given the high
sediment concentration often found in floodwaters.
 It is important to periodically operate these facilities
to ensure proper operation during a flood event.
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Flood plain zoning

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References
-Julien, P. Y. (2002). River Mechanics, Cambridge University Press, UK.
-Roberson, J.A., Cassidy, J.J., Chaudhry, M.H. (1998). Hydraulic Engineering,
2nd Edition,
Wiley Press, USA. US Army Corps of Engineers. (2010). After Action Report:
May 2010 Flood Event
Cumberland River Basin.
<http://www.lrn.usace.army.mil/LRN_pdf/AAR_May_2010_Flood_Cumberland
_Draft_V
7_21.pdf>