this presentation gives a brief about what are the different types of floods depending upon area & its cause.It is further aided with mitigation or management techniques to be implemented & types of damages.

2. Semester : BE - 5th Civil-A
Subject : Hydrology & Water Resources Engineering
Code : 2150602
Presentation On : Flood Management
Prepared by : Eddy Ankit Gangani
eddygangani@gmail.com

3.  What is Flood ?
 What is Flood Management ?
 Types of flood
 Causes Of Flood

4.  Flood : A flood is an
excess of water (or mud) on
land that's normally dry
and is a SITUATION
wherein the inundation is
caused by high flow, or
overflow of water in an
established watercourse, such
as a river, stream, or drainage
ditch; or ponding of water at
or near the point where the
rain fell.
This is a unpredictable -
duration type -natural and
inevitable event.

6.  According to Duration : Slow-Onset Flooding
Rapid-Onset Flooding
Flash Flooding
 According to Location : Coastal Flooding
Storm surge
Arroyos/Mud Flooding
River Flooding
Urban Flooding

7. 1. Riverine Floods: The majority of floods recorded globally are due to rivers overflowing as a
result of long-lasting precipitation in the river basin. Melting snow and ice can also contribute
to flooding.
2. Flash Floods : Flash floods generally occur due to local high-intensity precipitation in hilly or
mountainous areas. The short warning time makes them difficult to predict. Discharges
during flash floods are often much higher than normal flows in water courses. Flash floods are
particularly dangerous on steep slopes.
3. Coastal Floods : Areas along the coast may be flooded due to tsunamis, hurricanes or/and
unusually high tides. Also long-term phenomena like subsidence and sea-level rise can lead to
the gradual encroachment of the sea.
4. Urban flooding : The urban area is paved with roads etc and the discharge of heavy rain can’t
absorbed into the ground due to drainage constraints leads to flooding of streets, underpasses,
low lying areas and storm drains
5. Stagnant and Urban Floods: Extreme rainfall in towns and cities combined with blocked drains
can cause severe flooding. This often occurs in urban areas, where a large percentage of the
surface is impermeable.
6. Lake and Canal Floods : High levels of precipitation or long-lasting inflows from streams can
cause a substantial rise in water levels of lakes and canals that lack sufficient drainage
capacity. Also, long periods of drought can cause man-made (peat) embankments to become
unstable and fail – resulting in flooding.

8.  Uncontrolled unplanned urbanization - Unauthorized colonies , Poor Water and Sewerage Management
 Deforestation + Population pressure
 Lack of Flood Control Measures
 Lack of attention to the nature of hydrological system
 Slope Failures
 Type of River
 Intensity of Rainfall
 Topography
 Sedimentation of River/Reservoir
 Obstructions in River flow
 Contraction in River
 Seismic effects

9. Mitigation
Measures
Mitigation
Measures
Flood plain zoning
Flood forecasting
Flood proofing
Mathematical
modeling
Response
planning
Modifying loss
burden
Reservoirs-Flood gates
Levees
Flood wall
Floodways
Flood bypass
Watershed
Cut-off
Rain Water Harvesting
Channel improvement
Drainage improvement
Watershed management

10.  Reservoirs & Flood gates -
Reservoirs can moderate the intensity and timing of the
incoming flood.
Floodgates are used to control the flow of water and can
be a part of flood prevention.
Floodgates are often incorporated into reservoir, river,
stream, levee, or storm surge systems.
Water flow can be either partially restricted or
completely stopped, depending on the water level and
desired effect.
Expensive & potential error .

11.  Levees - A levee is a barrier built to keep a river, or
other waterway away from people or
sensitive habitats.
Important considerations
 First, it is important not to remove too much
floodplain storage. Excess removal could restrict
flood waters and slow drainage upstream.
Second, levees are designed to protect an area
from a certain flood level and storm intensity. If
these levels are exceeded, a levee may be
overtopped or may fail completely.
Third, in order for a levee to continue functioning
properly and provide security for those behind it, a
levee should be regularly inspected and
maintained.

12.  Floodwall -
When construction space is low then
a flood wall is implemented to protect
low lying area.
Does not reduce the flood flow but
reduce spilling
Acts as a retaining wall
Section : Rectangular trapezoidal
Sheet piling

13. Mitigation Measures
• Cut-off -
To have high
velocity of water flow
along a straight path
To avoid ox bow
lake
Does not reduce the
flood flow but reduce
spilling

14. Mitigation Measures
• Watershed Management -
Long term effect
Examples ; Afforestation
Contour farming
Check dams
Gullying
Bank protection
Diversion drains

15. Mitigation Measures
• Flood ways -
Low lying are(depressions ) along the
river course is known as floodways.
Connected to natural channel or
artificial channel
Temporary storage
Can be used for agriculture other
than flood.
Do not reduce the flood flow but reduce
spilling

16. Mitigation Measures
• Flood plain zoning-
 Oftentimes floodplain management is not
contained in a single comprehensive
document, but instead is incorporated
into other rules, guidelines, or
regulations, including:
• Floodplain Management Ordinance
• Encourage appropriate development
• Community Master Planning
• Flood Hazard Zoning
• Open Space Preservation Ordinance
• Education and Outreach
• Emergency Management Program
• Mapping Program or GIS

17. Mitigation
Measures
• Flood forecasting -
 For emergency evacuation
 Flood forecasting through range
of hydrodynamic/ snowmelt /
flood routing models.
 Flood warnings
 CWC National Flood
Forecasting Network

18. Mitigation
Measures
• Flood proofing -
 Combination of structural change
& emergency action.
 Water proofing materials on windows
 Water tight closure on doors
 Example : use of flood wall or levees
on periphery of building

19. Indirect Damage
Direct
Damage
Flood Damage Analysis
• clean-up costs
• disruption to
transport services (
disbility to provide
community services)
• disruption to
utilities
• disruption to
public & emergency
services
• economic impacts
of health issues
• damage to building
• external damage (pools,
gardens, fences, shed
contents)
• motor vehicles
• infrastructure (roads,
bridges and other services)
• clean-up costs for individual
home owners
• loss of stock
• cost of re-instatement or
rebuilding of houses and
buildings.
Tangible Damage

20. Non-monetary losses -
variability
-Loss of life & cattle
-- Loss of health
-Loss caused by social
distress
-Loss due to hindrance in
development work
-Physical ailments
Flood Damage Analysis
Intangible Damage

21.  Where applicable, the best practices described in here
should be taken into ac-count, in particular on:
 Integrated river basin approach
 Public awareness, public participation and insurance
 Research, education and exchange of knowledge
 Retention of water and non-structural measures
 Land use, zoning and risk assessment
 Structural measures and their impact
 Flood emergency
 Prevention of pollution