Reduction of total salinity in groundwater using hydraulic barrier / Pamela Duanne Catura, Ina Joana Garcia

UTHESIS (Bachelor of Science in Agricultural and Biosystems Engineering)

Bibliography: leaves 46-48

Paguludan-Salindeg, Currimao, Ilocos Norte is characterized as a highly saline area, where initial salinity levels averaged 5691.50 ppm, significantly exceeding the 500.0 ppm (PNSDW) threshold limit for groundwater salinity in coastal areas. The study evaluated the effectiveness of hydraulic barrier in reducing saltwater intrusion in shallow tube wells. The study had the following objectives; (a) To verify of the presence of total salinity in shallow tube wells; (b) To identify the actual time (minutes) to fill 40 m3 and 60 m3 freshwater used to recharge the deep wells; (c) To identify a functional relationship between actual and predicted total salinity; (d) to determine the cost incurred during freshwater addition in 40 m3 and 60 m3. The study area was included in a GIA-funded research program of NRCP-Water Security in Philippine Coastal Aquifers where the database was generated. A drum with a volume of 200 liters was filled with water using the same pump set and setting that was used in the study area and was clocked. Groundwater from the shallow tube wells were daily monitored for 14 days after each recharging activity. Then QGIS was used to digitize the changes of the level of salinity in Barangay Paguludan-Salindeg throughout the monitoring period. In developing the functional relationship between actual and predicted total salinity, a scatter diagram was plotted to determine the trend of the data as to whether the salinity levels change linearly or non-linearly with respect to the number of days with freshwater injection. Cost incurred revealed the expenses associated with freshwater injection where one laborer for setting up and monitoring the water pumps, 30L of diesel fuel, and 16L of distilled water used for cleaning the data meter. Reduction of total salinity was evident in the generated functional relationship where there was a significant difference at STW 1, 2, 4, and 5 for 40 m3 freshwater recharging, and a significant difference at STW 1, 2, 3, and 4 for 60 m3 freshwater recharging.