http://drw.jfn.ac.lk/handle/123456789/56 2026-04-19T23:36:03Z 2026-04-19T23:36:03Z Karthiga, I. Rameshwaran, P. Ketheesan, B. Sriskandarajah, N. http://drw.jfn.ac.lk/handle/123456789/417 2024-07-01T01:20:34Z 2023-01-01T00:00:00Z

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 De Silva, C.S. http://drw.jfn.ac.lk/handle/123456789/203 2022-02-11T07:56:35Z 2015-01-01T00:00:00Z

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 Shanmuhananthan, S. Jehangir, F. P. http://drw.jfn.ac.lk/handle/123456789/157 2021-11-26T10:02:41Z 2011-01-01T00:00:00Z

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 Sivakumar, S.S. http://drw.jfn.ac.lk/handle/123456789/144 2021-09-29T04:28:21Z 2014-01-01T00:00:00Z

Application of electronic spread sheet and water balance error optimization technique in ground water model study to improve the ground water system in restricted area Sivakumar, S.S. A study was carryout for a restricted ground water catchment about 160 sq. kilo meters in Vavuniya in Northern Sri Lanka to find out an operational policy of minor and medium Irrigation schemes, to recharge the ground water system to increase the economic pumping. Forty one wells were identified as observation wells within the study area of 160 sq. kilo meters to represent the aquifer. This study area was divided into forty one Thiession polygons by connecting the perpendicular bisectors of adjoining observation wells with four year seasonal collected (Oct.2000 - May.2004) water levels and three years seasonal historic (Oct.1997 - May.2000) water levels. A ground water simulation model was formulated for this polygonal network using integrated finite difference method in spreadsheet. The model was calibrated for the period from 1997 to 2001 having eight seasons. Since the initial values were taken as October 1997, the time step t was taken as 8 months followed by 4 months. These time steps were used alternatively throughout the calibration period from 1997 to 2001. The rainy season was taken from 1st October to 31st May of next year and non-rainy season was taken from 1st June to 30th September.By this calibration the hydrogeological stress parameters such as Transmissibility, Storage coefficient, Recharge coefficient for Irrigation scheme, Recharge coefficient for irrigation field, Recharge coefficient for rainfall and the Withdrawal factor for agro and domestic pumping were found using optimization technique. A complete water balance study for each polygon for each season was carried out. Forty one error models were prepared for the water balance, for each polygon for all the season. MATHCAD2000 was used for this optimization. Using the results obtained a validation of the model was carried out with three seasonal water level (Oct.2001 – May 2003). The model successfully predicted the water levels with very little error (less than three percent). This integrated finite difference model in spreadsheet & calibrated by error optimisation technique, validated and was used to predict the system behaviour for various operational policy of the Vavuniya restricted ground water catchment during this research. This article elaborates the use of electronic spread sheet and the use of optimization packages in this research work to formulate a ground water simulation model in any restricted catchment.

2014-01-01T00:00:00Z