http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/5663 2026-04-15T09:10:23Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/3391 Suitability of Groundwater for Drinking in Valukkai Aru Drainage Basin Sheetharon, M.; Mikunthan, T. The surface stream, Valukkai Aru, in Jaffna Peninsula, Sri Lanka is only active during the monsoon and there are no reservoirs of a perennial nature. There are complaints by farmers regarding salinity problem in this area in the recent past. Freshwater availability is limited in the Valukkai Aru drainage basin area. Hence the study was aimed to assess the suitability of groundwater for drinking purpose. Initially, 114 wells were selected and groundwater samples were tested only for pH and EC. Based on EC, pH, land use and well type, 40 wells were chosen and groundwater samples were collected during the driest period, June 2020. Groundwater sample was analyzed by the standard methods for pH, electrical conductivity, total alkalinity, total hardness and chloride. Measured data were used to assess the suitability of groundwater for drinking purpose by comparing with the Sri Lanka Standard (SLS). Out of selected 114 well, only 8% of the selected wells were suitable for drinking purpose since the electrical conductivity of the groundwater was below the SLS desirable level of 750 μS/cm. Around 33% of the wells were not suitable for drinking or irrigation purpose since EC values were above the 3500 μS/cm. But most of the sample pH was within the range of 6.5 to 8.5. Total Hardness values were ranged between 232 - 3921 mg/L and 95% of the samples exceeded the SLS values for drinking water (250 mg/L) due to the dissolution of limestone and the substantial contribution from the weathering of limestone. Total alkalinity varied from 88 to 657 mg/L and 75% of the wells were above the recommended SLS desirable level of 200 mg/L. The concentration of chloride was between 47 and 8830 mg/L and 75 % of the samples exceeded the SLS desirable value for drinking water. High chloride concentration indicates the intrusion of seawater. The results reveals that the groundwater is not entirely fit for drinking with respect to EC, total hardness, total alkalinity and chloride. 2020-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/3390 Analysis of Rainfall Pattern over the Iranaimadu Tank during the Last Three Decades Lathiscumar, S.; Umasuthan, S. Iranaimadu tank is one of the major irrigation tanks in Northern Province of Sri Lanka. Water from this tank is used to irrigate agricultural lands in the Northern Province. Predictions on rainfall patterns are useful in planning the irrigation projects. The main objectives of the study are to examine the monthly and seasonal variation of rainfall and the rainfall trends over the Iranaimadu tank. This study was conducted using the monthly rainfall data of the past thirty years (1984 – 2018), which were collected from the Iranaimadu tank weather station. The analysis was carried out using monthly and seasonal mean rainfall data. The past three decades were divided as 1984-1994, 1995-2004 and 2010-2018 for the analysis. Magnitudes of the rainfall trends were derived by using linear regression analysis. The study reveals that the highest monthly rainfall was recorded in November. Further, March, June and July recorded less than 50 mm of mean monthly rainfall. Highest seasonal rainfall (553.8 mm) was recorded in Second Inter-Monsoon (SIM) and this was 40.51% of the total annual rainfall. Further, least seasonal rainfall of 106.2 mm (7.8%) was recorded during the First Inter-Monsoon (FIM). and it was 7.76% of the total annual rainfall. An increasing trend in the average monthly rainfall over the past three decades clearly found through the linear trend analysis, R2 value is 0.9385 in December, which is statistically significant. Further, decreasing trend in the average monthly rainfall clearly shown in the linear trend analysis, where, R2 value is 0.9984 in January. FIM and North East-Monsoon showed an increasing trend in the seasonal rainfalls with the R2 values of the FIM was 0.4910 and 0.4654, respectively. Further, South West-Monsoon and SIM also showed a slightly increasing trend even though the changes were not statistically significant. In addition, average annual rainfall also showed a slightly increasing trend during the last three decades but not statistically significant. 2020-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/3389 Design, Fabrication and Performance Evaluation of Millets (Eleusine coracana) Cleaning Machine for Domestic Level Palugaswewa, K.I.T.M. Finger millet is one of the most important food in human diet in the past as same as at present; because it contains large amount of nutrients. At the same time finger millet has a high demand in the society because most of diabetic patients are recommended to include finger millet in their diets. At present cleaning of finger millet is done manually, but it is rather difficult because it takes more time to separate impurities from the threshed finger millet. Many types of processing equipment have been developed and these machines are expensive and require more electricity to operate. However there is no machine has been developed to separate impurities from the threshed finger millet in domestic level. As a solution for this, a finger millet cleaning machine was designed, fabricated and evaluated at the National Institute of Post-harvest Management, Anuradhapura. The evaluation of the machine performance was done based on the following parameters: separation efficiency, separation loss, cleaning efficiency, cleaning loss at different feed rate, sieve slope and motor speed. Three level of sieve slopes (00,30,50), three level of motor speeds (250,500,750 rpm) three level of feed rates (125, 250, 500 g/min) were used. The experimental design was three factor factorial with CRD. The minimum losses and maximum efficiencies were achieved at 50 sieve slope, 500 rpm and 250 g/min feed rate. At that level the machine capacity was 15 kg/hr, separation efficiency 95.23%, and cleaning efficiency 99.5%. Cost for the machine was Rs 10,000.00. Therefore this machine can be introduced as lower cost and easy to operate finger millet cleaning machine for domestic use. 2020-01-01T00:00:00Z http://repo.lib.jfn.ac.lk/ujrr/handle/123456789/3388 Analysis of Residual Chlorine Concentration in Water Distribution System in Vavuniya District Thinarthika, T.; Mikunthan, T.; Prabhaharan, M.; Saravanan, S. Per Aru reservoir is located in Vavuniya District and water from the reservoir is treated through the water treatment plant. Chlorine is used as a disinfectant and it should ensure that there is a constant minimum residual chlorine level (RCL) in all the parts of a distribution system. Further, the factors that influence chlorine decay should be identified. On this basis, the study was aimed to analyze the RCL concentration along the distribution system and find the locations with lower RCL concentration than the acceptable range (0.2 - 0.5 mg/L) and possible reasons for lower concentrations. A field study was conducted at the water distribution system connected to the Marakkarampalai overhead tank by collecting water samples at different locations. Totally 31 locations in the distribution system were selected. Water samples were analyzed for RCL concentration, pH, dissolved oxygen (DO) and temperature at the site itself. Collected data on RCL were statistically analyzed with one sample t-test, paired t-test and Duncan multiple range test. Information on the water distribution system; age of the pipe, pipe materials and diameter and distance from the overhead tank was collected. Results revealed that there was no significant difference in RCL concentration measured in different time periods however a significant difference was observed among the data collection points on the same day. The RCL concentration among the Marakkarampalai distribution system varied from 0 mg/L to 1.01 mg/L. Pattanichurpuliyankulam and Thirunavatkulam areas showed very low RCL concentration. Temperature of the collected water sample varies from 27.4 °C to 33.8 °C. Temperature range from 31 °C to 32 °C shows the acceptable RCL concentration. Higher temperature causes high RCL decaying which results in low RCL in consuming water. The pH and DO do not influence on RCL in consuming water. There was no any clear relationship recorded for pH and DO against RCL. Pipe age, Pipe material and Pipe diameter have no influence on residual chlorine decaying in this distribution system. Further, nearby areas to overhead tank shows sufficient amount of RCL in consuming water. However, the areas which are far away from the overhead tank and complex designed areas show lower amount of RCL in consuming water. Hence, actions need to be taken to ensure drinking water supply with acceptable range of chlorine in this water distribution system. 2020-01-01T00:00:00Z