http://drw.jfn.ac.lk/handle/123456789/25 2026-05-12T16:18:58Z http://drw.jfn.ac.lk/handle/123456789/417 Groundwater mapping and locally engaged water governance in a small island terrain: Case study of Karainagar island,Northern,SriLanka Karthiga, I.; Rameshwaran, P.; Ketheesan, B.; Sriskandarajah, N. Groundwater is a vital resource under threat in island communities. Karainagar, a 22km2 island, is one of seven islands off the coast of Jaffna in Northern Sri Lanka, with its population of just about 11,000 persons, experiences seasonal water shortage, and salinity in groundwater as twin threats impacting on their lives. This paper reports on a 3-year study (October 2019 to September 2022) to map groundwater dynamics of Karainagar island spatially and seasonally and discusses the patterns revealed interms of community needs, policy implications, and governance ideas that could already be considered by relevant authorities and citizens jointly. Thirty-six dug wells used for drinking, domestic, agricultural, and public purposes were selected, and water level, salinity, and pH changes recorded along with daily rainfall. This paper offers a thorough description of the geography, land use, distribution of wells, and water bodies, followed by discussion of the current status of the groundwater in Karainagar island. Year-to-year differences in rainfall pattern resulted in different rates of change and range in water level with a corresponding reverse pattern seen in salinity with some exceptions across the island. Cumulative rainfall required to reach full capacity of wells ranged from 652 to 892 mm over the 3 years with an average figure of 739 mm of rain. This implies that any further rainfall during early phase of the main rainy season is potential surface water for storage and runoff. Practices such as unregulated pumping and construction of tube wells are argued to be contributing to increase in salinity levels with health implications for residents. A participatory governance approach that overcomes limitations of the existing institutional approach is proposed. Its success based on broad stake holder engagement, improved equity, and transparency when supported by adequate policies and village level aquifer monitoring will enable sustainability of ground water resources in Karainagar. 2023-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/207 Efficient management in water supply: A study at Araly Water Supply Scheme, Jaffna Peninsula. Saravanan, s.; Thavendrakumar, B.; Thushyanthy, M.; Gunaalan, K. The demands for water supply, irrigation, domestic and industrial water have increased considerably in recent past in Jaffna district. The shallow karstic aquifer in Jaffna peninsula is one of the six main groundwater aquifers of Sri Lanka. Jaffna peninsula is underlain by Miocene limestone formations which are generally 100 to 150 m thick.The karstic cavities result in a shallow groundwater table,recharged by rainfall, and groundwater forms a “lense” of fresh water floating over the saline waters.Groundwater is the major natural water source in the Jaffna peninsula and it is used for domestic, agricultural and industrial purpose. Safe drinking water supply is a vital important where the water resources are under vulnerable conditions.The vulnerability may arise from natural and anthropogenic effects including local climate, geology and agricultural practices. In Sri Lanka 40% of population has organized water supply facilities and 59.4% is depending on other sources such as wells,tube wells,streams and rivers,including 10% on unprotected sources.Water quality analysis is one of the most important phase in water supply schemes. Determination of physico-chemical characteristics of water is essential for assessing the suitability of water for various purposes like drinking, domestic, industrial and irrigation. National Water Supply & Drainage Board, Jaffna is supplying the drinking water for identified poor quality groundwater area and plays a major role in supply of drinking water for rural and urban population of peninsula by maintaining seven water supply schemes to fulfill their water requirements.Araly is the one of their scheme.It is the shallow well with the bottom depth of 4.30 m.The secondary data such as water level fluctuation, electrical conductivity of bottom and surface groundwater and production were collected analyzed on monthly basis from 2011 to 2013. Results show that during the wet season the water level varies 2.4 m to 3.8 m and during the dry season it varies as 0.3 m to 1.6 m. Electrical conductivity varies from 189 μS/cm to 6190 μS/cm.During the wet season the water quality parameters were nearly same at bottom and the surface of the well water but during the dry season those parameters show significant variation between the bottom and surface of the well water.Bottom quality 3 values were higher than the surface values.Average production of the groundwater was 820 m /month. Earlier the pumping was carried out for three hours continuously but now the pattern of pumping was altered and do not pump continuously,there was a resting time after pumping of every one hour.Now 3 the production was increased up to 2272 m /month.To protect the water quality deterioration and aquifer, alteration in the pumping pattern is a good practice and also usage of low pumping rate water pumps and floating foot valves during the pumping operations could facilitate further. 2014-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/203 Simulation of potential groundwater recharge from the Jaffna Peninsula of Sri Lanka using HYDRUS-1D model. De Silva, C.S. In drier regions, accurate knowledge of groundwater recharge is important for the sustainable management of scare water resources. Thirunelvely in Jaffna Peninsula is an area where groundwater is being utilized for domestic, agricultural and municipal water supply. Further the groundwater in this area also contaminated with nitrogenous fertilizer application due to intensive agriculture, as post war conditions in the Peninsula encourage farmers to engage in intensive agricultural activities. Very few or no studies have been conducted in the recent past on groundwater recharge or solute transport such a fertilizer leaching in this area. HYDRUS-1D is a Windows-based modelling environment for analysis of water flow and solute transport in variably saturated porous media. HYDRUS-1D is just as quick and cheap as other soil moisture balance models but more physically based and flexible as it allows for building up complexity as data are available whether for solute transport or non-equilibrium flow etc. Therefore the main objective of this paper is to simulate potential groundwater recharge using HYDRUS-1D and compare it with the results obtained in Thirunelvely using soil moisture balance and water table fluctuation methods. Results have shown that the HYDRUS-1D simulated potential groundwater recharge (41.8 cm) has close agreement with that estimated by other methods with high coefficient of determination (R2 = 0.95). Further runoff, soil moisture storage and bottom pressure head simulated by HYDRUS-1D too have good agreement with field observation. Therefore HYDRUS-1D is capable of simulating potential groundwater recharge close to the previously estimated values in Thirunelvely as it has good agreement with the water table fluctuation measured in the study site and the bottom head pressure at the 1 m soil profile simulated in the HYDRUS-1D model. Now that it has been demonstrated that HYDRUS-1D adequately reproduces the water fluxes predicted by other methods, it could be used for groundwater recharge with more confidence and to investigate pollution in soil zone and groundwater. 2015-01-01T00:00:00Z http://drw.jfn.ac.lk/handle/123456789/157 Groundwater Modelling to Predict Management Options for Kayts in Northern Sri Lanka Shanmuhananthan, S.; Jehangir, F. P. Kayts is one of several islands which lie off the western end of the Jaffna Peninsula in the northern- most part of Sri Lanka. A low salinity groundwater lens is the only promising source of fresh water on the island. The return of refugees in the post conflict period has raised concerns for the quantity and quality of groundwater available for drinking and agriculture and on increased risk of seawater intrusion and upcoming from unsustainably high extraction rates. The groundwater flow model MODFLOW, mass transport model MT3DMS, and salinity intrusion model SEAWAT were used to model the regional flow system and the interface separating the freshwater and saltwater flow systems, and for pumping and rainfall recharge scenarios. The water balance for the sand dune area in Kayts, found the available water from this region is 266 m3 /d. Preserving the sand dunes which are the only reliable source of potable water for Kayts remains a priority. 2011-01-01T00:00:00Z