Drought In Bangladesh

Throughout this presentation you
will learn

content
Introduction
To drought
Drought
in BD
Drought
index
SPI
Causes of
Drought
Types of
drought
Mathematic
al analysis
of Drought
Effects of
Drought
Drought,
poverty,
food
security

Drought Is
A lack or of for an unusually
period of , involving less than the
usual over 3 months
A lack or shortage of water for an unusually long period
of time, involving 50% less than the usual rainfall over 3
months

 What do you mean by drought?
 The word drought instantly brings image of dry, parched land,
no rainfall, crop failures, starvation and bad living conditions
to our mind.
 In simple terms, drought is a condition of acute scarcity of
water, food, fodder, and employment due to scanty rainfall in
an area.
DROUGHT

Definition of drought
1. CG Bates (1935) “ Annual precipitation is 75%
or less of normal precipitation and monthly
precipitation 60% or less of normal monthly
precipitation.”
2. British Rainfall Organization (1936) “Absolute
drought: when are at least 15 consecutive day with
less than 0.01inch of rainfall per day.
Partial drought: When there are at least 29 days
having mean rainfall of 0.01 inch or less.
Dry spell: When 15 consecutive days receive less
then 0.04 inch of rainfall per day.”

Definition of drought
3. J.C Hoyt (1936) “Annual and monthly rainfall is
less then 85% of normal rainfall.”
4. V.A Conard (1944) “period of 20 or more
consecutive days without inch precipitation in 24
hours.”
5. D.A Ramdas (1950) “ When rainfall for a week is
half normal or less.”
6. A.J Henry (1960) “ 21 days or more when rainfall
is 30% or less of average rainfall. Extreme drought
occur when rainfall is less then 10% of average
rainfall for 21 days or more.”

How a drought starts
A drought starts when total rainfall is well below average for
several months.
Other signs of drought include:
Very dry soil
Trees have a sign of dying
Weather getting hotter and hotter
Very dry soil

Drought causes can be classified in two way. These
are…
Natural
Global Warming
Deficiency of
Rainwater
Weather (hot +
dry)
EL-NINO
Soil Erosion
Human made
Overpopulation
Over cultivation
Deforestation
Over extraction
of ground water
Politics
CAUSESOF
DROUGHT

This has increased the average temperature and
caused climate changes to the earths atmosphere and
also causes drought.

 There are fore types of drought. These are follows:
Meteorological drought
Hydrological drought
Agricultural drought
Socioeconomic drought
Types of drought

 This kind is usually determined by the general lack of
moisture in the weather such as lack of precipitation, and
the play of other weather conditions such as dry winds,
high temperatures and so on. It is expressed in relation to
the average conditions of the region over a long period of
time. It is usually an indicator of potential water crisis if the
condition is prolonged. Meteorological drought can begin
and end immediately.
Meteorological drought

 This is when atmospheric moisture is reduced to the
extent that soil moisture is affected. Here, crops and
animals are affected and evapotranspiration is also
affected. It is often the signs one sees when a
meteorological drought is at play, but not before a
hydrological drought.
Agricultural drought

 This is when there is a deficiency of surface water and ground
water supply in a region, often as a result of less
precipitation, excessive reliance on surface water for farming,
energy and other needs. Hydrological drought does not
usually occur at the same time as meteorological drought. In
a way, this decline in the quantity and quality of surface and
sub-surface water is the effect of meteorological drought.
Hydrological drought

 This condition is when some supply of some goods and services such as
energy, food and drinking water are reduced or threatened by changes in
meteorological and hydrological conditions.
 Sometimes it is even made worse by growing populations and excessive
demands of such goods, to the point that it creates stress on the little water
available.
 It takes a very long time for this kind of drought to get into full gear, and a
long time to recover from it.
Socioeconomic drought

IDM(Indian Meteorological Department)
stated that there are two type of drought
1. Severe drought: when the deficiency of
rainfall excite 50% from normal rainfall
2. Moderate Drought: When the deficiency of
rainfall between 25% and 50% of normal
rainfall.
OTHER TYPES….

Types Of Drought And Their Impacts Over
Time, From Onset Of Drought To Realization
Of Impacts…….

 Drought affects all parts of our environment and our
communities. The many different drought impacts
are often grouped as “economic,” “environmental,”
and “social” impacts. All of these impacts must be
considered in planning for and responding to
drought conditions.
 Let's take a closer look at all kinds of drought
impacts.

 Farmers may lose money if a drought destroys
their crops.
 If a farmer's water supply is too low, the farmer
may have to spend more money on irrigation or
to drill new wells.
 Ranchers may have to spend more money on
feed and water for their animals.
 Businesses that depend on farming, like
companies that make tractors and food, may
lose business when drought damages crops or
livestock.
 People who work in the timber industry may be
affected when wildfires destroy stands of timber.
 Businesses that sell boats and fishing
equipment may not be able to sell some of their
goods because drought has dried up lakes and
other water sources.
Economic impacts are those impacts of drought that cost
people (or businesses) money. Here are just a few different
examples of economic impacts:

 Power companies that normally rely on
hydroelectric power (electricity that's
created from the energy of running
water) may have to spend more money
on other fuel sources if drought dries up
too much of the water supply. The power
companies' customers would also have
to pay more.
 Water companies may have to spend
money on new or additional water
supplies.
 Barges and ships may have difficulty
navigating streams, rivers, and canals
because of low water levels, which
would also affect businesses that
depend on water transportation for
receiving or sending goods and
materials.
 People might have to pay more for food.

Drought also affects the environment in
many different ways. Examples of
environmental impacts include:
 Losses or destruction of fish and wildlife habitat
 Lack of food and drinking water for wild animals
 Increase in disease in wild animals, because of
reduced food and water supplies
 Migration of wildlife
 Increased stress on endangered species or even
extinction
 Lower water levels in reservoirs, lakes, and ponds
 Loss of wetlands
 More wildfires
 Wind and water erosion of soils
 Poor soil quality

Social impacts of drought are ways that drought
affects people’s health and safety. Examples of
social impacts include:
 Anxiety or depression about economic losses
caused by drought
 Health problems related to low water flows and
poor water quality
 Health problems related to dust
 Loss of human life
 Threat to public safety from an increased
number of forest and range fires
 Reduced incomes
 People may have to move from farms into
cities, or from one city to another
 Fewer recreational activities

Comparison in normal and drought condition health

DROUGHT, POVERTY AND FOOD SECURITY

 Understanding drought and
environment.
 Water conservation.
 Pollution prevention.
 Storing and moving water.
 Rainwater harvesting.
 Afforestation.
 Geographical shifts of agricultural
system.
 Improve irrigation system.
 Climate-proofing rainfall based system.
 Computer based method should be used.
 Digging water reservoir.
 Artificial rainfall.

PREPARDNESS AND MITIGATION PLANNING FOR
DROUGHT

DROUGHT INDEX
 Precipitation Effective Index(PEI):
Following categories of the climate types have been defined on the
basis of PEI.
Climate Type Vegetation PEI Values
Wet Rain Forest >127
Humid Forest 64- 127
Sub Humid Grass and 32- 63
Semi Humid Steepen 16- 31
Arid Desert <16

Tools and Techniques for drought assessment
Satellite derived drought indicators calculated from satellite-derived
surface parameters have been widely used to study droughts.
Remote sensing and GIS technique is increasingly being regarded as
a useful drought detection technique, as evidenced by its use across
many parts of the world.
Some tools and technique for analysing drought using RS and GIS….
 Standardized Precipitation Index (SPI)
 Normalized Difference Vegetation Index (NDVI)
 Vegetation Condition Index (VCI) and
 Temperature Condition Index (TCI)

Standardized Precipitation Index (SPI), a tool derived by Tom McKee
(1993) et al., a measure of meteorological drought has been calculated
from the available rainfall data collected by the Bangladesh
Meteorological Department. Mathematically, SPI is calculated based on
the following equation
where, Xi is monthly rainfall record of the station;
Xm is rainfall mean; and
σ is the standard deviation
Standardized Precipitation Index (SPI)

METEOROLOGICAL DROUGHT RISKS
CLASSIFICATION USING SPI VALUES (MCKEE
ET AL., 1993)
SPI Values class Probability
2.0 and more Extremely wet 0.977–1.000
1.5 to 1.99 Very wet 0.933–0.977
1.0 to 1.49 Moderately wet 0.841–0.933
-.99 to .99 Near normal 0.841–0.933
-1.0 to -1.49 Moderately dry 0.067–0.159
-1.5 to -1.99 Severely dry 0.023–0.067
-2 and less Extremely dry 0.000–0.023

Drought in Bangladesh
 The northern region of Bangladesh has in recent decades has been afflicted by
recurrent and severe droughts, which in turn often led to intense food
insecurity, known locally as Monga.
 Every year, generally from mid-September through mid-November, this crisis
occurs. People call the period Mora Kartik, meaning the month of death and
disaster.
 Too little water in the rivers during the dry seasons and less rainfall creates
drought situations.
 Statistics show that 92% of water in Bangladesh comes via external rivers and
only 8% is local rainfall. The initial watersheds of all the major rivers in the
region run through neighbouring India, making Bangladesh is heavily
dependent on India for the availability of water resources. These rivers are the
lifeline for agriculture, industry and the domestic sectors.

 The construction of barrages, hydroelectric dams, and other
structural interventions in the upstream of these rivers heavily
obstruct the normal flow of water towards Bangladesh. India
often exploits these structures to withdraw water in the dry
months (generally from March to May) for irrigation, energy
production and economic uses. It creates tremendous stress on
surface water resources in the northern districts of Bangladesh
and causes a significant decrease in groundwater recharge,
resulting in the depletion of soil moisture.
 The scarcity of water in these areas has also been exacerbated
by the low and uneven distribution of rainfall in recent years
due to the effects of climate change.

 According to UNDP report the amount of water use per
person is 46 litters per day
 According to Bangladesh Meteorological Department
“There was 21 per cent less rain during the monsoon period
from June to August in 2009 and the northern districts
suffer from drought”.
 In Rangpur region 92 core litters/day water is extracted
 11 litters/sec Water extracted by deep tubewells and sallow
and deep tubewells run 180 and 175 days respectively in a
year.

 Drought is one of the major environmental stresses in the north
that drastically limits the grain yield of rice, a staple food of
Bangladeshi people. This causes a lot of people to become
unemployed and fall into acute food shortage between late July
and early November.
 During this interim period, there are no alternative agricultural
activities left for people and the small non-agricultural sector
cannot absorb the seasonally unemployed labour force. Hence,
food insecurity in the region is associated with yield reduction in
rice and non-availability of wage employment.

Drought In Bangladesh

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