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Salinity Intrusion in Interior Coast of Bangladesh: Challenges to Agriculture in South-central Coastal Zone

Mohammed Abdul Baten
School of Environmental Science and Management, Independent University Bangladesh, Dhaka, Bangladesh, and Unnayan Onneshan (Center for Research and Action on Development), Dhaka, Bangladesh

Lubna Seal
Unnayan Onneshan (Center for Research and Action on Development), Dhaka, Bangladesh, and Department of Geography and Environmental Management, University of Waterloo, Waterloo, Canada

Kazi Sunzida Lisa
School of Environmental Science and Management, Independent University Bangladesh, Dhaka, Bangladesh

Abstract/ Executive Summary:

This paper investigates the impacts of salinity on crop agriculture in south-central coastal zone of Bangladesh, more particularly interior coast. The coastal areas of Bangladesh, with near flat topography and location at the tip of “funnel shaped” Bay of Bengal, are susceptible to a number of natural hazards such as cyclones, tidal surges, salinity intrusion, riverbank erosion, and shoreline recession. To investigate extent of salinity level in interior coast and its impact on crop agriculture, this study tested irrigation water collected in between October and December 2011 from the lower Meghna at Gosairhat upazila in Shariatpur district and interviewed experts and local farmers. This study estimated that salinity concentration of surface water was 1.3 dS/m which was 0.8 dS/m higher than the earlier estimation by ICZMP (Integrated Coastal Zone Management Plan) in 2003. The study further revealed that Chloride ion concentration in irrigation water was 500 ppm, pH level was 7.99 and concentration of Carbonate ion was 221 ppm, which were much higher than the desired level. Estimated salinity concentration had already put a threat to the crop production and a significant yield loss already been noticed in dry season. In the changing scenario of sea level rise, it has been predicted that the increasing concentration of salinity would create more pressure on the farmer by reducing yield on one hand and threatening livelihood, income generation and food security on the other hand. Therefore, to reduce the future loss and prevent the present loss, the study recommends leaching and selection of specific salinity tolerant crop varieties as adaptation techniques.

Keywords: Agriculture, Interior Coast, Leaching, pH, Salinity Intrusion

Location:

Start Date: 00-10-2011

End Date: 00-12-2011

Program Area: Risk Management in Agriculture

Commodity: Impact

Objectives:

To measure the salinity level, more specifically irrigation water salinity, and its impact on agricultural production.

Methodology:

The study has employed both qualitative and quantitative approaches to collect and analyze data. Both primary and secondary sources were used to collect data. Primary data were collected in between October and December 2011 through: testing of soil and water samples to measure salinity level, Focus Group Discussion (FGD), Key Informants Interviews (KII), household interviews, and personal observation. Secondary data were collected through assessing a number of scientific and policy studies. Review of secondary literature helps to identify the level of salinity in previous years in different coastal district in Bangladesh and what impacts it have laid on agriculture. Water circulation in the coastal zone is largely dependent on the factors like fresh water flow from the river, penetration of tide from the Bay of Bengal and the meteorological conditions like low pressure systems, cyclones, and storms surge and wind. Both climatic and anthropogenic factors were found to be responsible for causing salinity in the fresh water river. Climatic factors, albeit others, such as sea level rise was considered as the imperative cause of salinity in coastal areas.

Source of Information: American Journal of Climate Change, 2015, 4, 248-262

Article Link (Online Journal): http://www.scirp.org/journal/PaperInformation.aspx?PaperID=57061

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Leaching and selection of irrigation time were found as useful determinant in managing low to moderate level salinity. Crops with a higher threshold value are likely to have lower leaching requirements and therefore, will require a less amount of irrigation water. On the contrary, low tolerance value requires high leaching that means more water is needed to increase the yield potentiality which will incur high production cost. Moreover, salinity in irrigation water also influences the soil salinity and pH. Higher pH in soil is likely to create a deficiency of nutrient like phosphorus, iron etc. To reclaim the nutrients, appropriate fertilizer should be applied against the deficiency of certain nutrient. For instance, to address the deficiency disease named “Lime-induced Chlorosis”, an Iron deficiency disease, Iron sulphate needs to be applied in the soil. High pH due to high salinity usually causes CO₃ and HCO₃ salt to be insoluble and therefore, creates Ca and Mg ions deficiency with the dominance of Na ion. To address the problem, gypsum or calcium sulphate could be applied to release Ca ion and replaces Na ion. Timing of irrigation is another important factor in managing salinity. A dry and hot day is likely to evaporate more water from soil and therefore, cause more salt to be concentrated in the plant root zone. Therefore, for irrigation, a cool and humid weather or night is preferable. The frequency of irrigation should be increased in case of a hot and dry weather to address salinity stress.

Knowledge Management: Journal