Transcript

Understanding climate risks and exploring adaptation strategy -

agriculture and water sector

MD. MAFIZUR RAHMAN

Professor

Department of Civil Engineering

Bangladesh University of Engineering and Technology (BUET)

[email protected]

International Conference on Sustainability Science in Asia, ICSS-Asia 2011

Vietnam National University, Hanoi 2-4 March, 2011

Organized by IR3S, The University of Tokyo, Vietnam National University (VNU)

Co-Organizers: AIT Vietnam and United Nations University (UNU)

Introduction

High temperature, heavy rainfall, often-excessive humidity, and

fairly marked seasonal variations are common phenomena in

climate of Bangladesh at present. Large percentage of the

population is already vulnerable to a range of natural hazards

with increasing climate variability. Climate change is expected to

aggravate the situation further by causing more frequent and

intense droughts and increasing temperatures. Safe water crisis,

shortage of food production and distress in human life are

simultaneously deepening day by day.

This presentation will show the present scenario of climate

change impact in agriculture and water sector along with its

possible adaptation strategy in Bangladesh.

Major natural disasters• Flood

• Cyclone

• Drought

• Earthquake

• Sunstroke

• Tornado

Major man-made disasters• Setting of fires

• Epidemic

• Deforestation

• Pollution due to prawn cultivation

• Chemical pollution.

Minor natural disasters• Cold wave

• Snow fall

• Thunder storm

Minor man-made disasters:• Road and train accidents

• Accidents due to festivals

• Food poisoning (poisoned food)

• Death due to excessive drink

• Industrial disaster/ crisis

• Rehabilitation

• Acid rain

• Riots

• Environmental pollution

• War

DroughtDrought is a severe natural phenomenon which at some

intervals occurs in Bangladesh and causes disastrous crop

failures.

In 1979 the country was hit by a severe drought, which was

termed by many as the worst in the recent past.

Droughts of 1957 and 1972 were of severe nature.

Specialty of Drought in Bangladesh lies in the fact that

Bangladeshi people are not familiar with this relatively

new event of Climate change

Trend of Climatic Parameters

• Dryness and drought are the phenomena derived from the

imbalance in climatic parameters.

• In this study, the trends of seasonal as well as annual

rainfall and seasonal temperature have been analyzed to

get the patterns of seasonal dryness and drought in

Bangladesh.

BMD Stations

Seasonal Rainfall Patterns

• North-west region of the country is generally considered asthe drier one. Observations on Rajshahi show that rainfallshave been increased over the considered period of time in allseasons except in monsoon.

• Temporal plots of the seasonal rainfall at all stations of thenorth-west region have shown increasing trends except inRajshahi during monsoon and in Chuadanga at winter.

• Pre-monsoon, monsoon and winter have become drier inComilla due to decreasing trends of rainfall in central region.

• In south-east part, pre-monsoon and monsoon rainfalls havebeen decreased during pre-monsoon and monsoonrespectively.

Seasonal Rainfall Trends in Rajshahi

Seasonal Rainfall Patterns

• Madaripur has the maximum negative slope of 9.61 mm/year,which indicates the station getting the highest dryness over timeduring pre-monsoon. Again the rate of getting dryness is theminimum in Chandpur having the minimum negative slope of0.38 mm/year.

• Comilla has got the driest monsoon with the rainfall trend having

maximum negative slope of 12.41 mm/year during monsoon.

• The negative slope of temporal trend of post-monsoon rainfall is

the maximum in Comilla (-1.48 mm/year), indicating the driest

post-monsoon in Comilla.

• The rate of decrease of winter rainfall is the maximum in Tangail,

which is indicated by the maximum negative slope of 2.20

mm/year.

Seasonal Temperature Patterns

• Increase in temperature instigates increase in

evaporation as well as evapotranspiration and hence

decrease in available water.

• Therefore, increase in seasonal temperature is a

critical issue to be studied to assess seasonal drought

scenario throughout the country.

Seasonal temperature trends in Rajshahi

Temperature Trends

Regional Patterns

• In the north-west and north-east regions of the country, no occurrence of

increasing temperature has been found, rather temperatures have been

observed to decline over the considered period of time.

• In central region, monsoon and post-monsoon temperature have been

increased in Dhaka. Monsoon temperature has also been increased in

Tangail of this region.

• From the temperature patterns of south-west region, it is found that

monsoon temperature has been increased in Barisal and Satkhira.

• Analysis on south-east region of the country represents that post-monsoon

temperatures have shown increasing trends in Feni, Chittagong and Cox’s

Bazar. Again, monsoon temperature has been found to be increased in

Cox’s Bazar.

Temperature Trends

Seasonal Patterns

• The maximum positive slope of temperature trend has been found as0.03 °C/year in Tangail, indicating maximum dryness among other drierstations during monsoon.

• Faridpur has become the driest having the maximum positive slope ofpost-monsoon temperature of 0.03 °C/year.

• The maximum positive slope of winter temperature trend has been foundin Patuakhali as 0.13 °C/year.

• It can be noted here that monsoons in Faridpur and Cox’s Bazar havebecome drier due to decreased rainfall (-2.21 mm/year and -0.07 mm/yearrespectively) as well as increased temperature (+0.02 °C/year and+0.01 °C/year respectively).

(a) Dryness map considering rainfall in winter 1999

(b) Dryness map considering temperature in winter 1999

(c) Dryness map considering rainfall and temperature in winter 1999

(a) (b) (c)

Impacts of Climate Change on

Some Crops of Some Selected Areas

Local Transplant Aman => Comilla District

Wheat => Dinajpur District

Potato => Bogra District

Mung bean => Jessore District

Impacts of Climate Change on Rice (Local Transplant Aman)

Rice (T. Amam) y = 0.0118x - 22.05

R2 = 0.1188

1.2

1.3

1.4

1.5

1.6

1990 1995 2000 2005Year

Yie

ld (

T/H

a)

Variation of T. Aman yield during the period 1992-2004.

Impacts of Climate Change on Wheat

Wheaty = -0.0038x + 9.6398

R2 = 0.0025

1.4

1.6

1.8

2

2.2

2.4

2.6

1991 1993 1995 1997 1999 2001 2003 2005Year

Yie

ld (

T/H

a)

Variation of wheat yield during the period 1992-2005.

Impacts of Climate Change on Potato (Local)

Potato

y = 0.1088x - 210.12

R2 = 0.5047

6

7

8

9

1990 1995 2000 2005

Year

Yie

ld (

T/H

a)

Variation of potato yield during the period 1992-2004

Impacts of Climate Change on Pulse (Mungbean)

Mungbean

y = -0.0119x + 24.411

R2 = 0.5701

0.5

0.6

0.7

0.8

1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

Yie

ld (

T/H

a)

Variation of mungbean yield during the period 1992-2004.

Simulated Yield for Rice y = 0.0116x + 1.4556

R2 = 0.6693

0

0.5

1

1.5

2

2.51992-9

3

1996-9

7

2000-0

1

2004-0

5

2008-0

9

2012-1

3

2016-1

7

2020-2

1

2024-2

5

2028-2

9

2032-3

3

2036-3

7

2040-4

1

2044-4

5

2048-4

9

Year

Su

mu

late

d Y

ield

(T/H

a)

Predicted rice (T. Aman) yield up to the year 2050.

Simulated Yield for Wheaty = -0.0088x + 2.0182

R2 = 0.3544

0

0.5

1

1.5

2

2.5

3

1992-9

3

1997-9

8

2002-0

3

2007-0

8

2012-1

3

2017-1

8

2022-2

3

2027-2

8

2032-3

3

2037-3

8

2042-4

3

2047-4

8

Year

Sim

ula

ted

Yie

ld(T

/Ha)

Predicted wheat yield up to the year 2050.

Simulated Yield for Potato y = 0.0339x + 7.1469

R2 = 0.4461

0

2

4

6

8

10

12

1992-9

3

1996-9

7

2000-0

1

2004-0

5

2008-0

9

2012-1

3

2016-1

7

2020-2

1

2024-2

5

2028-2

9

2032-3

3

2036-3

7

2040-4

1

2044-4

5

2048-4

9

Year

Sim

ula

ted

Yie

ld (

T/H

a)

Predicted potato yield up to the year 2050.

Simulated Yield for Mungbean

y = -0.0037x + 0.7037

R2 = 0.5446

0

0.2

0.4

0.6

0.8

1

1992-9

3

1996-9

7

2000-0

1

2004-0

5

2008-0

9

2012-1

3

2016-1

7

2020-2

1

2024-2

5

2028-2

9

2032-3

3

2036-3

7

2040-4

1

2044-4

5

2048-4

9

Year

Sim

ula

ted

Yie

ld (

T/H

a)

Predicted mungbean yield up to the year 2050.

Dinajpur District

• Agriculture is the main economic activity in Dinajpur.Because of the variety of physical conditions inDinajpur, cropping systems and crops varyconsiderably

– Kharif-I

• The Kharif-I season includes the period of early monsoon. B.Aus is themajor crop of this season

– Kharif-II

• The Kharif-II season includes the period of late monsoon. The main cropof this season, which is T. Aman depends on rainwater

– Rabi

• A number of crops are grown in the Rabi season. Boro is the primaryirrigated rice crop grown in this season, This crop has the highest recordof water demand among all crops

25

• Climate change scenarios comprise of greenhouse gas emission scenarioand regional pattern of climate change

• Emission scenario– IS92a emission scenario was selected for this study

• Climate change projection– The results of the HADCM2 and UKTR transient experiment models were used for

study area HADCM2 is regarded as one of the leading models in the world. UKTR hasbeen broadly used for impact assessment studies in different countries.

• Climate ModelHADCM2» Outputs obtained for 2050

» Outputs obtained for 2070

• Climate Model UKTR» Outputs obtained for 2050

» Outputs obtained for 2070

26

27

Assessment of the impact of climate change on Evapotranspiration…

Effects of Climate Change on Monthly evapotranspiration

28

Assessment of the impact of climate change on Crop Water Requirement…

Percentage of Change of Crop Water Requirement of B.Aus due to Climate Change

29

Assessment of the impact of climate change on Crop Water Requirement…

Percentage of Change of Crop Water Requirement ofT.Aman due to Climate Change

30

Assessment of the impact of climate change on Crop Water Requirement…

Percentage of Change of Crop Water Requirement ofBoro due to Climate Change

Solution

• Change of cropping pattern.

• Irrigation

To keep soil moisture and ground water level in acceptable limit the

following techniques can be adopted

– Infiltration ponds and basins

– Flooding

– Ditch, furrow, drains

– Deep well injection

– Recharge dam

– Channel spreading

Scenario of urban water

environment

Dhaka City

Year Population

(Million)

Growth Rate (%)

1950 0.5 -

1975 2.2 6.6

2000 10.2 7

2025 22.01 4

Average population density in Dhaka city-19286 person per sq.km. in 2005

• The total water demand for Dhaka city was increased from 150

million liter (ML) in 1963 to 2300 ML in 2010. In 1963 the total

deficit for water supply in Dhaka city was 30 ML which

substantially increased to 268 ML in 2010.

• The recharge to aquifer is very negligible because of the

geological settings and rapid urbanization.

• Consequently, groundwater table is continuously declining at an

average rate of 2m year-1, since 1986.

• This severe decline of groundwater level increasing tremendous

pressure on aquifer storage and inviting land subsidence or

other environmental hazards

Declination of Ground water

Trend of ground water depletion at different location in Dhaka city

(From 01/1992 to 01/ 2004)

DhanmondiCantonment

Sutrapur Sabujbag

Peripheral Rivers of Dhaka City

Peripheral rivers act as the

receivers of storm water,

municipal, and industrial

wastewater from Dhaka City

Over 300 outfalls of Domestic

wastewater and industrial

effluent from Dhaka city.

Effluents are discharged

indiscriminately without any

restriction.

Industrial Outlet on Lakhaya riverHazaribagh Sluice gate on Buriganga River

Dhaka Dying on Tongi cannel Chatbari Station, Mirpur on Turag RiverRiver Water Pollution

Probable Solution

• Rainwater harvesting

• Ground water recharge

• Efficient demand management

• Using water conservation fixtures

• Waste water reclamation and re-use

• Surface water treatment

Rainwater harvesting

City area: 370sq.km.

Avg. annual rainfall: 2m

Total vol. of rainfall: 740000 million liter

Concrete roof area available: 74.58 sq.km.

Yearly total vol. of rain water: 149140 million liter

If 60% of this water can be collected, then more than 200 MLD

water will be available for household use and artificial ground

water recharge.

Rainwater harvesting

Measures to be taken:

• Harvest roof top rain water and use it for

domestic non potable water requirements

• Excess rain water can be recharged in to

nearby underground water bodies such as

bore well or open wells to replenish the

ground water

Metering, Pricing & Taxing

Measures to be taken:

• Monitor the water consumption, install water meters

on down take line.

• Illegal connections must be blocked and system loss

should be reduced.

• Billing and collection of water and sewerage bills

should be computerized

Waste water re-use

Measures to be taken:

• Provide grey water treatment and use

recycled water for gardening / toilet flushing/

car washing

• Provide separate plumbing down take lines

from the source so that designated treatment

can be planned separately.

• Grey water to be collected and treated

separately and thus to recycled back for

toilet flushing or gardening.

Surface water treatment

Measures to be taken:

• Surface water intake points have to be

identified effectively.

• A second intake upstream from the

Saidabad intake at the Lakhya River can

serve the area east of Uttara (Newly

developing northern part of Dhaka city).

• Intake at the Meghna river (One of the large

rivers) near Baidyer bazar can server the

people of Narayanganj.

Pilot survey for piped water supply system

Upazilla: Bandar.

District: Naraynganj.

Name of the

Village

Total nos. of

households

Population Total Population

Male Female

Ali Nagar 182 648 570 1218

Gharmora 310 1226 1054 2280

Char

Gharmora

309 972 870 1842

Total 801 2846 2494 5340

Distribution of Households Income Source

Name of the

village

Farmers Service Business R/V

Pullar

Day

Labour

Others Total

Gharmora 15 119 149 4 4 19 310

Chor Gharmora 30 102 122 10 45 0 309

Alinagar 2 66 55 2 57 0 182

Total 47 287 326 16 106 19 801

Income group Status Income Range Nos. of HH

G-1 Very poor Less than TK. 1,000 5

G-2 Poor TK.1,000 to TK. 3,000 39

G-3 Medium income group TK.3,001 to TK. 5,000 178

G-4 Rich TK.5,001 to TK. 10,000 450

G-5 Affluent income group Above TK. 10,000 129


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