Flood & drought management

FLOOD & Drought
MANAGEMENT
October 28, 2021
Prepared By:- Sonu Saw

Agenda
 What is flood & it’s types.
 Measuring Parameters.
 Flood Management
 Flood plain zones.
 Flood Forecasting.
 What is Drought, It’s Classification.
 Cause of Drought.
 Drought Management Options.
 Drought Proofing Techniques.
01

• Floods are an excess of water that covers land
that is normally dry.
What is Flood?
• According to the International Commission on
Irrigation and Drainage (ICID), ‘Flood’ is defined as a
relatively high flow or stage in a river, marked by
higher than the usual, causing overflow of low land
or a body of water, rising, and overflowing land that
is not normally covered under water.
02

Two Main Floods
 Flash Floods:- This type of floods
occurs when heavy rainfall persists
for only a short time period. Yet can
cause major damage due to their
sudden arrival.
 Flash Floods can also be caused by
dam bursts or overflows.
 Riverine Floods:- This type of floods occurs
when water rises above its natural banks,
often caused by snowmelts in combinations
with prolonged and heavy precipitation.
 Riverine foods take days, weeks , or
months to rise to its max & return to normal,
much longer than it takes a flash flood to.
03

Measuring
Parameters  There are 6 categories to measure the flood severity in a
region:-
 Depth of Water.
 Duration.
 Velocity.
 Rate of Rise.
 Frequency.
 Depth is simply how deep the water is.
 Duration is how long the water lasts for.
 Velocity is how quick the water is moving., the faster it moves the more damage done.
 Rate of rise is how quickly the depth of the water increases.(Important when giving to evacuate
areas).
 Frequency is how often floods occur in an area , which depends greatly on the topography and
04

 Flood Management
 Structural Measures
i. Floodwalls & flood embarkments.
ii. Flood storage in reservoir/ Dam.
iii. Channel Improvements.
iv. Di-Silting(to remove suspended silt
from a basin) and Dredging( to clear
the mud) of Rivers.
v. Drainage Improvement.
 Non-Structural Measures
ii. Floodplain zooning.
iii. Flood insurance.
i. Flood forecasting and warning.
05

 Flood Plain zones
Continued…
08
Zones Flood Return Period Example of Uses
01
02
0
3
100 Years
25 Years
Frequent
Residential House, Offices,
Factories, etc.
Parks
No construction/
Encroachments

Flood
Forecasting
09
Continued…
Flood forecasting is the prediction of streamflow
rates levels and water levels for periods ranging
from a few hours to days ahead, depending on the
size of the river basin.
Utility:-
 Flood disaster
management.
 Optimal reservoir
operation.

What is Drought?
 Drought are considered as natural phenomenon and represents a relevant
temporary decrease of the average water availability.
 Drought events have regular occurred producing severe socioeconomic &
environmental impacts, 7 have increased considerably over the past 30 years.
 Occurrence of droughts may not be controlled. However the resulting impacts
can be mitigated, by appropriate surveillance and management strategies (
Drought Management Plan).
 “16% of country’s total area is drought prone and 68% of total sown area can be
drought affected”.
 “50 million people are expected to be annually affected”.
10

Classification of Drought
 Metrological Drought.
 Hydrological Drought.
 Agricultural Drought.
 Socio-economic Drought.
 Metrological Drought:- Reduction in rainfall for a specified period
(summer , winter ,monsoon).
 Hydrological Drought:- Depletion of water resources, stream flows,
ground water, underground aquifers, etc.
 Agricultural Drought:- Impact of metrological or hydrological drought on
crop yields.
 Famine Drought:- Extreme form of agriculture drought, which destroys
food security to maintain as active healthy life.
11

Hydrological Drought
• From a hydrologist’s point of view , drought means below average
values of streamflow, reduced storages in tanks & reservoirs,
groundwater and soil moisture.
Three Components of Hydrological Drought:-
i. Magnitude.
ii. Duration.
iii. Frequency of Occurrence.
14

Metrological
Drought
Continued…
It is the situation where there is more than 25%
decrease in precipitation from normal over an area.
In India, the metrological drought is in general related
to the onset, breaks and withdrawal times of
monsoon in the region.
Types:- 1. Normal Drought.
2. Moderate Drought:- 50% of normal value.
3. Severe Drought:- 25%-30% of normal value.
15

Causes of Drought
Continued…
A. Deficiency of Rain Water.
B. Dependency on rain-fed agriculture.
C. Human Causes:- a) Over exploitation of ground water resource.
b) Land use leading desertification.
c) Deforestation .
d) Over-cultivation.
e) Overgrazing.
12

Droughts in India
Continued…
13

Drought Proofing Techniques
 Creation of water storages through appropriate water resources development.
 “Inter-basin transfer” of surface waters from surplus areas to drought prone areas.
 Development of “management of groundwater potential”.
 Development of appropriate water-harvesting practices.
 Economic use of water through drip, sprinkler irrigation, etc.
 Reduction of evaporation from soil & water surfaces: mulching, ground cover.
 Development of afforestation , agro-forestry and agro-horticulture practices.
18

 Review Paper 01
Year Article Name Author Result
2010
Integrated Flood
and Drought
Management for
Sustainable
Development in the
Nzoia River Basin
Dulo S.O
Odira P.M.A
Nyadawa M.O
Okelloh B.N
Wetlands are
needed in the
catchment to
hold excess
water so it can
recharge
groundwater.
Rainfall
accumulates
much more
quickly on land
paved with roads
and covered by
homes and
shopping
centers.
19

 Review Paper 02
Year Article Name Author Result
2011
Integrated Flood
and Drought
Management for
Sustainable
Development in the
Kagera River Basin
O. Munyaneza,
C. Ndayisaba,
U.G. Wali,
D.M.M.
Mulungu
and S.O. Dulo
The reliability of
forecasts can be
increased in
various ways,
such as:
• Improvement
of rainfall
forecasts.
• Improved
catchment
modelling; •
Improved
channel routing;
and
• Improved
model updating
techniques.
20

References
1.) APFM, 2004. Integrated Flood Management.
Edited by TECHNICAL SUPPORT UNIT. The
Associated Programme on Flood Management.
2.) Bertilsson, P. and Jägerskog, A., 2006.
Integrated Water, Sanitation and Natural
Resources Initiative in the Lake Victoria Region.
Stockholm International Water Institute (SIWI)
3.) Burton, J. Integrated water resources
management on a basin level, a training manual,
Canada, 2001.

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