Impact of Brackish Water Shrimp Farming on Agricultural Land and Surrounding Environment in the Southwest Coastal Zone of Bangladesh

Transcription

1 Impact of Brackish Water Shrimp Farming on Agricultural Land and Surrounding Environment in the Southwest Coastal Zone of Bangladesh A.F.M. Tariqul Islam 1,2, Umme Kulsum Navera 2 and M. Golam Mahboob 1 1 GIS & RS Lab, T&C Wing Bangladesh Agricultural Research Institute (BARI) 2 Department of Water Resources Engineering Bangladesh University of Engineering & Technology (BUET) BENJapan Webinar/Teleconference on Environment Aspects (WEA-22) April 7, 2012

2 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

3 Background 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 waterlogging These two factors together worked as a catalyst to the process of accelerated shrimp farming

4 Fig. Map of coastal zone showing main shrimp farming upazila 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

5 Objectives 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

6 Study Area Study Area 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

7 Data used Types of data Year Source Landsat MSS 09 Feb, 1977 Landsat TM 14 Nov, 1990 SPARRSO Landsat TM 4 Nov, 2004 Fresh water area Environmental data November, 2008 GPS survey November, 2008 Questionnaire survey

8 Methodology Processed and Classified images Landsat MSS 1977 and TM 1990, 2004 Conduct Questionnaire Survey Find out types of Environmental Impact Extract Area statistics Trend analysis Report

9 Procedure RS and GIS data used for monitoring development shrimp farming during 1977 to 2004 A survey was carried out using GPS to locate freshwater fisheries area. The land use status for actual brackish water shrimp farms, crop land, water bodies and settlement area along with its changing trend from the year 1977 to 2004 were calculated A total of 99 respondents were interviewed from this upazila with a preset open ended questionnaire interview schedule Then the local peoples perception was observed to find out the types of environmental degradation due to shrimp farming

10 Results & Discussion A. Impact of shrimp farming on agricultural land Fig: Satellite and Classified Images of Kaligonj upazila, 2004

11 Area (ha) Comparison changes of major land use classes Results & Discussion Land use change pattern between year of 1977 and 2004 Upazila: Kaligonj Shrimp Crop Land Water Settlement

12 Area (ha) Results & Discussion Changes in Agricultural Land and Shrimp Farming 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

13 B. Impact of shrimp farming on environment 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.

14 (i) Effects of shrimp farming on salinity Major causes of increasing salinity due to Shrimp Farming (SF) % of responses Unplanned expansion of bagda gher caused salinity Ghers contaminate adjacent land through seepage Shrimp farm caused salinity increase in ground water Shrimp farming caused water logging problem Saline water in the rivers and canals caused land salinity Adding extra salt into the water to ensure better growth of shrimp 5.29 Total

15 Map showing max. soil salinity in 1973 and 2000 in coastal zone Source: SRDI 1973 Source: SRDI 2000

16 ii. Effects of shrimp farming on land fertility Major causes of decreasing land fertility due to SF Salinity due to shrimp farming reduce yield capacity Shrimp farming decreased fruits and vegetables production Excess use of chemicals in shrimp farming reduced yield of crops % of total responses Shrimp farming reduce the organic matter Total

17 iii. Effects of shrimp farming on health hazards Major causes of health hazard due to SF % of responses Shrimp farming increased epidermis diseases Increased risk of malnutrition to common people Shrimp waste disposal directly to environment without treatment Health hazards due to unhygienic shrimp processing Increased mosquitoes which consequent disease Shrimp farming caused gastro-intestinal diseases Total

18 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. Decreased livestock due to shrimp farming During collecting shrimp fry, fish and all other species are destroyed Expansion of shrimp farming caused decrease the native fishes like Rui, Katla Shrimp farmers killed some local animals: frogs, crabs etc Total

19 v. Effects of shrimp farming on Water scarcity Major causes of water due to SF Responses (%) Fresh water pond decreased due to gher expansion Water pollution due to excess use of chemical used in shrimp farm Scarcity of irrigation water due to shrimp farming Hand tube wells are out off order or produce saline water Ground water contaminated due to shrimp farming Total

20 women and school going children are to walk a long distance look for available filtered water or non saline tube wells or ponds. Source: UNEP, 1999

21 Conclusion 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 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

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