Investigation of the Effectiveness of Salt Barrages in Jaffna Peninsula
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Date
2012
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Uva Wellassa University of Sri Lanka
Abstract
The Jaffna Peninsula which is the northernmost tip of Sri Lanka has its groundwater source in the subsurface limestone layer. Due to over exploitation of groundwater for agricultural needs, most wells in the region have become brackish. Therefore, a supply source to replenish the wells to meet the increasing demand for fresh water is of paramount importance. Converting the two internal saltwater lagoons, Vadamarachchi and Upparu, to fresh water lakes 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. Making these lands suitable for cultivation and fresh water prawn farming in the banks of the lagoon are also expected (Shanmugarajah, 1993).
The Upparu lagoon with surface area of about 26 km2 has opening to the sea towards the south and is mainly a saltwater lagoon. During the north-east monsoon rain water fills up the lagoon lowering its salinity. Saltwater barrages have been erected in the mid-1900s to convert the lagoon into a fresh water lake (Rajasooriyar et.al., 2002). However, the barrages have not functioned properly and have allowed the salt water to intrude. Repair and replacement of these barrages were completed in October 2009.
Currently the effectiveness and the efficiency of the Ariyalai barrage of Upparru lagoon is monitored by the Irrigation Department by observing the salinity of surface water in five locations every month. This research focuses on evaluating the effectiveness of the Ariyalai barrage by delineating the saltwater intrusion pattern and groundwater flow pattern within the area extending from the fringe of the lagoon into the land for 2 km. The larger area coverage is expected to provide a more realistic picture of the saltwater intrusion patterns and hence a correct assessment of the effectiveness of the barrages.
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Mineral Resources and Technology