Browsing by Author "Rupathasan, N."

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    INVESTIGATION OF THE EFFECTIVENESS OF UPPARU SALT BARRAGE IN JAFFNA PENINSULA (3 Stage)
    (Uva Wellassa University of Sri Lanka, 2015) Rupathasan, N.; Udagedara, D.T.; Jayawardhane, D.T.
    The Jaffna Peninsula is located in the northern Sri Lanka. The total area of the Jaffna Peninsula is and demarcated three internal lagoons such as Thondamanaru, Upparu and Valukiaru. The first two lagoons comprise of an area of 77.6 km and 25.9 km . They are connected to the sea and drain an area of 518 km . Majority of the local community of the area is depending on agriculture and fishing. Groundwater is the main source for people in Jaffna Peninsula for domestic and agricultural activities. According to the field observations even people having their own wells, majority of them are affected by salt water intrusions. Therefore, they depend on the common water supply given by the government for drinking purposes, whereas some people still depend on groundwater sources. Recently, barrage was constructed as a salt water exclusion bund to convert the salt water in lagoon Upparu to fresh water lake. This is expected to improve available water resources of the peninsula, both in recharging the underground storage (Sukanya, 2012). This research is focus of the area from the fringe of the lagoon into the land extending around 2 km. Major aim of the research is to evaluate the effectiveness of the barrage by delineating the salt water intrusion pattern especially in the west and northwest areas of the lagoon. Methodology Existing aquifer types, geology and topography were studied with the help of available resources and monitoring was done in the area. Wells were selected in a circle to the fringe of Upparu lagoon. The areas coming under study are parts of Nallur, Kopay and Chavakachcheri divisional secretariat divisions. Electrical conductivity (EC) of the groundwater was measured during wet and dry seasons. The wells in which EC show a sudden change was selected for further chemical analysis (sodium and chloride). In addition, both wet and dry season sixty eight (68) shallow well samples were selected for sampling. Water samples were collected in PETF bottles, acidified and capped tightly. Water samples were analyzed for Na using Varian Atomic Absorption Spectrometer (AAS 240 series) facility available at the Uva Wellassa University. Chloride was measured with argentometric method. Spatial distribution of the chemical & physical parameters in the groundwater was interpolated using Inverse Distance Weighted method available in Arc GIS 9.3 software. Results and Discussion Results of this study show that EC values for groundwater in the study areas varies between 574 µS/cm and 23,470 µS/cm in wet seasons and between 544 µS/cm and 22,810 µS/cm in dry seasons. Element chloride values range between 449.8mg/L and 7,197.7 mg/L in wet seasons and between 949.7 mg/L and 4,098.7 mg/L in dry seasons. Sodium values vary in between 38.3 mg/L and 802.9 mg/L in wet seasons and between 26.7 mg/L and 648.4mg/L in dry seasons.
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    Investigation of the Effectiveness of Upparu Salt Barrage in Jaffna Peninsula (3rd Stage)
    (Uva Wellassa University of Sri Lanka, 2014) Rupathasan, N.
    Jaffna is a peninsula which is 1000 km2 of land covered by Indian Ocean by 160 kin of coastline and no location is more than 10 km away from the coast. Hence it is very much susceptible to the salt water intrusion in to the land area. The water resource mainly the underground water in Jaffna Peninsula is totally polluted due to prolonged negligence and improper management of existing barrages and the salt water intrusion was taken place due to the none- maintenance of SWE blinds. In addition to these garbage and soakage pit pollution and increased usage of fertilizer chemicals also affected the ground water. As a result, people are facing problem in getting good quality water in their wells. Due to the salt water intrusion, hundreds of acres of lands, hundreds of wells are in abandon stage. To convert the internal salt water lagoon Upparu, to fresh water lake is expected to improve the water resources of the peninsula, both in recharging the underground storage with additional surface storage and desalinating the lands fringing the lagoons and making suitable for cultivation (Shanmugarajah, 1993) and fresh water prawn farming in the banks of the lagoon. This research focus on the area from the fringe of the lagoon into the land extending for 2 km perpendicularly to evaluate the effectiveness of the barrage by delineating the salt water intrusion pattern and ground water flow pattern. Wells were selected in a profile perpendicular to the fringe of Uppu Am and Jaffna lagoon. The areas coming under study are parts of Nallur, Kopay and Chavakachcheri D.S Divisions. Electrical conductivity (EC) values and water level were measured in , situ for groundwater samples which were drawn from 78 wells in each month of January and July. Sixty shallow well samples were selected for chemical analysis out of 78 wells in which EC was measured. Water samples were analysed to determine Chloride and Sodium. EC values for groundwater in the study areas vary between 574 RS/cm and 23,470 RS/cm in wet seasons between 544 µS/cm and 22,810 µS/cm in dry seasons. Chloride values vary in between 449.8mg/L and 7,197.7 mg/L in wet seasons between 949.7 mg/L and 4,098.7 mg/L in dry seasons. Sodium values vary in between 38.3 mg/L and 802.9 mg/L in wet seasons and between 26.7 mg/L and 648.4mg/L in dry seasons. drt3 Ground water quality is comparatively high in Upparu lagoon in both seasons. According to the effectiveness of the barrage the ground water in the fringe of the lagoon will become fresh in the coming years. We are hoping that the continuation of the researches in future will provide a better result. Most of the researchers feel that the conversion of fresh water lagoons shall make very big contribution to the GWT (70%-80% of the total requirement) but the side effects of this conversion also has to be analyzed environmentally, socially and economically.