http://drw.jfn.ac.lk/handle/123456789/51 Tue, 12 May 2026 16:17:28 GMT 2026-05-12T16:17:28Z http://drw.jfn.ac.lk/handle/123456789/403 Spatial distribution of groundwater salinity at coastal region in Jaffna Peninsula: A case study at Karainagar Saravanan, S.; Thushyanthy, M.; Gunaalan, K.; Duleep, G. The supply of drinking water and accessibility of irrigation water at Karainagar divisional secretary division, demands the knowledge of groundwater features, in particular salinity, in order to avoid displacement of people from the area and to uplift the agricultural sector. The scope of this work is to determine the well density, identification of suitable wells for drinking and for irrigation based on the electrical conductivity, and to obtain the spatial distribution of groundwater salinity. All the wells present in Karainagar about 2697 wells were surveyed with the well head parameters and quality data as, type of well, usage pattern. purpose of usage, water withdrawal method, distance from the toilet. depth and diameter of the well, pH and EC during June 2011 to October 2011 and in September 2012 to October 2012 during the most drier period. All the wells were point marked in satellite images of the study area and geo referenced by using Are view 3.2. The surface water storage structures were also marked to increase the storage capacity of the runoff water which enhances the recharge. Layers were produced so as to select suitable wells for drinking and agricultural activity based on the Sri Lankan drinking water standard and irrigation water quality. Most of the wells are protected Wells 66.44%, and non protected dug wells and rube wells are 32,78% and 0.78% respectively Regarding water withdrawal, 67,41% hand bucket, 6.90% electric motor. 13.83% use pulley, 0.74% electric water pump and 0.30% use balance pole are used to extract water from the wells pH of all the wells were under the Sri Lankan drinking water quality standards, as 6.5-8. In case of electrical conductivity 11 61% wells were within the SLS maximum permissible level (3500S) and 76.16% wells were exceeding to limits maximum as high salty and the balance wells were empty. Though 11 61 of the wells were below the drinking water standard, the pumping of water for drinking from these wells source way not possible Because the results of step pumping test showed high electrical conductivity of groundwater was pumping duration due to up corning of salt water. Finally Karainagar ares obviously show the water scarcity for drinking water and for irrigation Only 116 of well water could be used for consumption even though 67 4% of well water extracted by hand bucket, sea water influences the quality of the well water. Hence drinking water should be supplied to the Karainagar area through pipe born water. Tue, 01 Jan 2013 00:00:00 GMT http://drw.jfn.ac.lk/handle/123456789/403 2013-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/279 Assessing the Quantity and Quality Controls of the Freshwater Lens on a Semi-Arid Coral-Limestone Island in Sri Lanka Wu, C.L.R.; Stigter, T.Y.; Craig, S.G. Uncertainties in the contamination and salinization mechanisms of the freshwater lens (FWL) in the semi-arid coral-limestone aquifer of Delft Island, Sri Lanka threatens its water security. The processes governing the quality and distribution of the FWL were therefore investigated through recharge assessment and hydrochemical analysis. Potential groundwater recharge zones based on land classification and geology were first identified. A rootzone water balance model was then built, which revealed the spatiotemporal variability of potential groundwater recharge occurring rapidly during the wet season (October to January) and most abundantly on pasture land underlain by yellow and brown sand. Recharge also varied largely between dry and wet years. Where the water table was shallow, intense rainfall in wet years was seen to result in surface flooding. Geochemical modeling using PHREEQC combined with diagrams (Piper and Stiff) and scatter plots, including stable water isotopes, revealed the meteoric origin of groundwater with salinization mainly caused by seawater mixing and slight evaporation. Findings also suggest that salinization is driven by the island's low-lying nature (maximum elevation of 6 m above sea level), the low hydraulic heads (maximum of 3.7 m above sea level), the shallow depth of the marine water, the presence of lagoons in the center which are inferred to be in hydraulic continuity with the ocean, and to some extent by unregulated abstraction of groundwater through shallow hand-dug wells. We hypothesize about infiltration and percolation of saline water through the root zone during storm inundations near the coast, supported by the combined occurrence of high values of partial CO2 pressure, alkalinity and salinity in groundwater samples. Cation exchange showed indications of salinization of wells mostly in low lying areas (minimum Na/Cl value of 0.66), and freshening in areas near the coast with high potential groundwater recharge (maximum Na/Cl value of 1.04). Elevated nitrate concentrations (maximum of 2.55 mmol/L NO−3) in groundwater samples were observed. This suggests that anthropogenic contamination is further threatening the already scarce resource as well as coastal ecosystems that may be groundwater dependent. Sat, 01 Jan 2022 00:00:00 GMT http://drw.jfn.ac.lk/handle/123456789/279 2022-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/263 Impact of seawater intrusion bund on soil & water conservation along the coastal line of Poonakary, Sri Lanka. Sanjeepan, S.; Weerasinghe T.K.; Satheeswaran, S. Saltwater intrusion into coastal aquifers is reported at coastal region of Poonakary, Kilinochchi district. A sea water intrusion bund was constructed by United Nations Development Programme in 2015 to reduce the issues with seawater intrusion. This study aimed to measure the variations of soil salinity and pH before (2015), just after (2016) and three years after (2018) the construction of bund and to identify the impacts of seawater intrusion bund on soil, water quality and crop improvement in the area. The study was conducted in three selected Grama Niladari Divisions of Poonakary, during July to September period in 2018. Soil samples were collected from 30 locations at different sampling depths and the locations were recorded by using GPS and fifteen water samples were collected to measure the water quality parameters and the values compared with WHO standards. A questionnaire survey was conducted to assess the crop improvement in the selected locations. When comparing the soil pH in 2016 and 2018, at all depths except 60cm, changes were highly significant and at 60 cm, it was significant. The Soil EC during 2016 and 2018 revealed that, at 15cm, 30cm and 60cm the changes were significantly different and at 45cm it was not significantly differ due to hardpan formation. A considerable improvement in the water quality and yield improvement of paddy were observed. The study reveals that, the seawater intrusion bund can be considered as a potential permanent solution for seawater intrusion at Poonakary. Fri, 01 Jan 2021 00:00:00 GMT http://drw.jfn.ac.lk/handle/123456789/263 2021-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/242 Salinity variations in surface water systems in Delft Island Sri Lanka Sivashanthini, K.; Gunaalan, K.; Harichandra, K.; Sutharshiny, S.; Warnasuriya, T.W.S.; Ragavan, N. The present study was carried out to identify the locations and salinity variations of surface water systems in Delft Island. Regular field visits were made from January 2016 to January 2017, GPS locations for all water systems were taken using GARMIN GPS and plotted in the digital Delft Island map using ArcMap. Water depth (cm) and salinity (ppt) were measured using meter rod and hand held refractometer, respectively. A total of 37 ponds and 23 water holes were identified. Area of the waterholes ranged from 7.08 m2 for Murugan kovil kerny to 194.94 m2 for Makkikundu Kerny. The largest (647300 m2 in area) and the deepest pond (150 cm in depth) were Periyakalikkulam and Sinnaveddukulam, respectively. All the ponds and water holes contain shallow water during rainy season except one pond namely Veddukalikulam. During the dry season, ten ponds and one water hole were not holding water; it is probably due to the bottom nature in the Delft Island. The average salinity of all surface water systems was 2.25 ppt during the wet season while it increased to 8 ppt during dry season. When considering the ponds, the highest salinity (15 ppt) was measured in Upputhannikulam during wet season and in Vannankalikulam (34.3 ppt) during dry season. Almost, zero value of salinity recorded in all the water holes during wet season, but an increased value of 15.2 ppt observed in Kuravady kerny in dry season. Higher value observed for the temporal scale of the salinity in most ponds could be due to the consequence of the saltwater intrusion into surface water systems in the Delft Island. The present study provides the status of salinity in ponds and water holes of Delft Island. The baseline data provide valuable information for local community, government officials, limnologists, researchers and policy makers in pond management. Keywords: Delft Island, ponds, salinity, waterholes Acknowledgements: Authors are grateful to Mangroves for the Future, Colombo (Grant No: FF/07) with Danida, Norad and Sida for the financial support. Tue, 01 Jan 2019 00:00:00 GMT http://drw.jfn.ac.lk/handle/123456789/242 2019-01-01T00:00:00Z