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Level of salinity of ground water in Jaffna Penninsula Sri Lanka

Congress: 2008
Author(s): THUSHYANTHY MIKUNTHAN
department of Agricultural Engineering Faculty of agriculture University of Jaffna Jaffna Sri Lanka
AbstractGround water is excessively exploited from the aquifers resulting to drawdown of the water table and subsequent contamination of the aquifer by sea water upcoming and intrusion mainly in coastal area and where presence of thin mantle of floating fresh water lens. Certain part of Jaffna peninsula also experiences such catastrophic and ground water became saline. Ground water of such areas affects the hardcore of the agricultural production and quality of drinking water. The electrical conductivity value and chloride concentration of ground water are the most efficient geophysical tool used in detecting the salinity. A closer study of the salinity distribution pattern of ground water in coastal and main land was selected as specific objective. Ground water sample was collected from forty wells in the coastal areas from April to December 2005 in fortnight interval and 80 wells from the main land in monthly interval from March to August 2007 for the analysis of chloride and electrical conductivity measurement. On the basis of amount of chloride concentration, 23% of the wells sampled in the Peninsula had soft water (less than 100ppm) and 10% of the wells were with hard water (greater than 300ppm). Only 1.6% of the wells had the water over 1000ppm and not recommended for any use. Rests of the 65.4% of wells were in between soft and hard water. Electrical conductivity value ranges from 300S/cm to 3.63dS/m. The water of the majority of the wells categorized as low salinity water within the range of 0 0.25dS/m. How ever, there were a few wells, which had the water with medium salinity that ranged from 0.25 to 0.75 dS/m. If groundwater with excessive salinity is used for irrigation purposes, it may lead to build up of salinity on the ground surface making it not suitable for agriculture. Hence the fresh water lens should be managed properly to eliminate the problem of sea water intrusion and up corning the sea water.
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