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Impact of Brackish Water Shrimp Farming on
Agricultural Land and Surrounding
Environment in the Southwest
Coastal Zone of Bangladesh
A.F.M. Tariqul Islam1,2, Umme Kulsum Navera 2 and M. Golam Mahboob1
2 Department of Water Resources Engineering
Bangladesh University of Engineering & Technology
(BUET)
1 GIS & RS Lab, T&C Wing
Bangladesh Agricultural Research Institute (BARI)
BENJapan Webinar/Teleconference on Environment Aspects (WEA-22)
April 7, 2012
Outline of the presentation
1. Background
2. Materials and Methods
3. Results
- Impact of shrimp farming on agricultural Land
- Impact of shrimp farming on coastal environment
4. Conclusion
Coastal shrimp farming in Southwestern areas is an age old
practice
Local people used to practice traditional aquaculture
They used tidal water for aquaculture in paddy field in Jan~Jul
In 1960s govt. made polders in this coastal area which ended
traditional shrimp aquaculture for few years
After 1970, strong international market demand and high prices
encouraged farmers to resume shrimp farming in polders
Rice cultivation no longer financially viable to due to salt water-
logging
These two factors together worked as a catalyst to the process of
accelerated shrimp farming
Background
Rapid expansion of shrimp culture caused rising concern due
to its adverse effect on the coastal environment
It is damaging the traditional agricultural systems and
unbalancing the socio-economic scenarios of the affected
areas
Fig. Map of coastal zone showing main shrimp farming upazila
To find out the trend of agricultural land encroached
due to increasing shrimp farming
To find out the impacts of increasing Shrimp Farming
on surrounding environments
Objectives
• Kaligonj upazila, Satkhira district, Bangladesh
• between 22º 21' to 22º 33' N and 88º 58' to 89º 10' E
• brackish water area of south-western part of Bangladesh
Study Area
Study Area
Types of data Year Source
Landsat MSS 09 Feb, 1977
SPARRSOLandsat TM 14 Nov, 1990
Landsat TM 4 Nov, 2004
Fresh water area 11-20 November, 2008 GPS survey
Environmental data 11-20 November, 2008 Questionnaire
survey
Data used
Trend analysis
Find out types of Environmental
Impact
Report
Conduct Questionnaire
Survey
Extract Area statistics
Processed and Classified images Landsat MSS 1977 andTM 1990, 2004
Methodology
RS and GIS data used for monitoring developmentshrimp farming during 1977 to 2004
A survey was carried out using GPS to locatefreshwater fisheries area.
The land use status for actual brackish water shrimpfarms, crop land, water bodies and settlement areaalong with its changing trend from the year 1977 to2004 were calculated
A total of 99 respondents were interviewed from thisupazila with a preset open ended questionnaireinterview schedule
Then the local peoples’ perception was observed tofind out the types of environmental degradation dueto shrimp farming
Procedure
Results & Discussion
A. Impact of shrimp farming on agricultural land
Fig: Satellite and Classified Images of Kaligonj upazila, 2004
Comparison changes of major land use classes
0
5000
10000
15000
20000
25000
Are
a (
ha)
Shrimp
Cro
p Lan
d
Water
Settl
emen
t
Land use change pattern between year of 1977 and 2004
Upazila: Kaligonj1977 1990 2004
Results & Discussion
Changes in Agricultural Land and Shrimp Farming
-15000
-10000
-5000
0
5000
10000
15000
1977-1990 1990-2004
Are
a (
ha)
Agricultural Land Shrimp Farm
RS data indicated that the agricultural land decreased gradually only
due to increase of rapid expansion of brackish water shrimp farming
as other land uses remaining almost the same
Results & Discussion
The survey results showed that the people’s
perception about environmental degradation due to
increasing saline water shrimp farming were:
increasing salinity both in soil and water
decrease land fertility
health hazards
loss of biodiversity
water scarcity etc.
B. Impact of shrimp farming on environment
Major causes of increasing salinity due to Shrimp
Farming (SF)
% of
responses
Unplanned expansion of bagda gher caused salinity 24.86
Ghers contaminate adjacent land through seepage. 23.16
Shrimp farm caused salinity increase in ground water 17.51
Shrimp farming caused water logging problem 15.25
Saline water in the rivers and canals caused land salinity 14.12
Adding extra salt into the water to ensure better growth
of shrimp
5.29
Total 100.00
(i) Effects of shrimp farming on salinity
Map showing max. soil salinity in 1973 and 2000 in coastal zone
Source: SRDI 2000Source: SRDI 1973
ii. Effects of shrimp farming on land fertility
Major causes of decreasing land fertility
due to SF
% of total
responses
Salinity due to shrimp farming reduce yield
capacity30.92
Shrimp farming decreased fruits and
vegetables production27.63
Excess use of chemicals in shrimp farming
reduced yield of crops23.68
Shrimp farming reduce the organic matter 17.76
Total 100.00
iii. Effects of shrimp farming on health hazards
Major causes of health hazard due to SF % of
responses
Shrimp farming increased epidermis diseases 20.56
Increased risk of malnutrition to common
people
18.22
Shrimp waste disposal directly to environment
without treatment
17.76
Health hazards due to unhygienic shrimp
processing
15.89
Increased mosquitoes which consequent
disease
14.48
Shrimp farming caused gastro-intestinal
diseases
13.08
Total 100.00
iv. Effects of shrimp farming on Biodiversity
Major causes of loss of biodiversity due to SF % of
Responses
Shrimp farmers destroyed habitats for wild
animals, birds , etc.
28.25
Decreased livestock due to shrimp farming 27.68
During collecting shrimp fry, fish and all other
species are destroyed
23.16
Expansion of shrimp farming caused decrease
the native fishes like Rui, Katla
19.21
Shrimp farmers killed some local animals: frogs,
crabs etc
18.64
Total 100.00
v. Effects of shrimp farming on Water scarcity
Major causes of water due to SF Responses
(%)
Fresh water pond decreased due to gher
expansion
25.00
Water pollution due to excess use of
chemical used in shrimp farm
20.92
Scarcity of irrigation water due to shrimp
farming
19.89
Hand tube wells are out off order or
produce saline water
18.37
Ground water contaminated due to shrimp
farming
15.82
Total 100.00
Source: UNEP, 1999
women and school going
children are to walk a
long distance look for
available filtered water or
non saline tube–wells or
ponds.
The major findings of this study are stated as follows:
(1) During 1977 there was no shrimp farm whereas in 2004
shrimp farming area encroached 36.44 percent of
Kaligonj upazila
(2) The satellite images data provided the information that
the shrimp farming areas have encroached the
agricultural land mainly
(3) The peoples’ perception showed that the study area
experienced serious environmental degradation due to
unplanned expansion of brackish water shrimp farming
(4) Proper planning, regulation and motivation are needed
to develop an environment friendly shrimp farming to
avoid ecological disasters in the coastal zone
Conclusion