In this study, we used a comprehensive set of statistical metrics to investigate the historical trends in averages and extremes of rainfall and temperature in Sri Lanka. The data consist of 55 years (1961–2015) of daily rainfall, maximum temperature (Tmax), and minimum temperature (Tmin) records from 20 stations scattered throughout Sri Lanka. The linear trends were analyzed using the nonparametric Mann–Kendall test and Sen–Theil regression. The prewhitening method was first used to remove autocorrelation from the time series, and the modified seasonal Mann–Kendall test was then applied for the seasonal data. The results show that, during May, 15% of the stations showed a significant decrease in wet days, which may be due to the delayed southwest monsoon (SWM) to Sri Lanka. A remarkable increase in the annual average temperature of Tmin and Tmax was observed as 70% and 55% of the stations, respectively. For the entire period, 80% of the stations demonstrated statistically significant increases of Tmin during June and July. The daily temperature range (DTR) exhibited a widespread increase at the stations located within the southwestern coast region of Sri Lanka. Although changes in global climate, teleconnections, and local deforestation in recent decades at least partially influence the trends observed in Sri Lanka, a formal trend attribution study should be conducted.

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Chunnakam aquifer is the main lime stone aquifer of Jaffna Peninsula. This study focused on characterization of Chunnakam aquifer for its suitability for irrigation. Groundwater samples were collected from wells to represent different uses such as domestic, domestic with home garden, public wells and farm wells during January to April 2011. Important chemical parameters, namely electrical conductivity (EC), chloride, calcium, magnesium, carbonate, bicarbonate, sulfate, sodium and potassium were determined in water samples from 44 wells. Sodium percentage, Sodium adsorption ratio (SAR), and residual Sodium Carbonate (RSC) levels were calculated using standard equations to map the spatial variation of irrigation water quality of the aquifer using GIS. Groundwater was classified based on Chadha diagram and US salinity diagram. Two major hydro chemical facies Ca-Mg-Cl-SO 4 and Na-Cl-SO 4 were identified using Chadha diagram. Accordingly, it indicates permanent hardness and salinity problems. Based on EC, 16 % of the monitored wells showed good quality and 16 % showed unsuitable water for irrigation. Based on sodium percentage, 7 % has excellent and 23 % has doubtful irrigation water quality. However, according to SAR and RSC values, most of the wells have water good for irrigation. US salinity hazard diagram showed, 16 % as medium salinity and low alkali hazard. These groundwater sources can be used to irrigate all types of soils with little danger of increasing exchangeable sodium in soil. However, 2 % of the wells are not suitable for irrigation due to very high salinity and sodium hazard.

The present study was undertaken to characterise the spatial and temporal dynamics of physico-chemical parameters of the Batticaloa Lagoon in Sri Lanka during November 2012 to October 2013. Eighteen sampling locations were clustered based on their positions from the Palameenmadu bar mouth. Physico-chemical parameters like temperature, electrical conductivity (EC), total dissolved solids (TDS), pH, salinity, dissolved oxygen (DO), turbidity, nitrate, phosphate and total suspended solids (TSS) were measured 15-30 cm below the water surface. The study revealed that the water temperature of the lagoon varied between 26.