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Asia-Pacific Network for Global Change Research

Asia-Pacific Network for Global Change Research

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Study of salinity levels and impact of saltwater intrusion on coastal paddy areas of wet zone of Sri Lanka

Paddy is the staple food crop in Sri Lanka. The productivity of most of the paddy lands in the coastal zone of Sri Lanka declines every year due to salinization caused by tidal waves and sea water, which are linked to climate change-induced sea level rise. This study focused primarily on the problem of salinity in the coastal paddy fields due to salt water intrusion in the wet zone of Sri Lanka. Soil samples were collected from salinity-affected paddy fields in 5 districts of the wet zone. The soil samples were collected in time gaps and checked for electrical conductivity and pH. Monthly rainfall data of these districts for the study period (May-September 2018) were collected from the Meteorological Department. The rainfall data and salinity data were analyzed using regression analyses. Two sample ttests were carried out between the mean salinities of the site/s assumed to be of high salinity and a referral site with no salinity impact within a district. The mean salinities between the wet and dry periods of each salinity-affected site were compared. Farmer surveys were conducted to gather information on socioeconomic aspects related to the salinity problem in the wet zone. There was a statistically significant correlation between the rainfall and the salinity levels. It was observed that in certain areas there was a statistically significant difference between the means of the salinity in the wet period and dry period, whereas in some areas there was no statistically significant difference between them. The overall results indicated that most of the sites have salinity levels (1-3 dSm-1) which can threaten the productivity of those lands. Therefore, it is recommended to the responsible authorities to take long term actions for the optimal control of salinity in the coastal paddy fields before it gets worse with time.