SPATIAL ANALYSIS OF GROUNDWATER RESOURCES POTABILITY DURING WET SEASON IN KORONADAL CITY, SOUTH COTABATO

The study was conducted to assess and determine the groundwater potability of Koronadal City, South Cotabato from different sources such as shallow tube wells, springs, artesian wells and deep wells by generating an overall potability map based on the groundwater parameters namely, electrical conductivity, E. coli, hardness, mercury, nitrate, pH level, phosphate, total dissolved solids, total suspended solids and turbidity using Quantum Geographic Information Software (QGIS 2.14.4) during the wet season. A total of 29 sample points were selected in the study in which 23 were shallow tube wells, two for deep well, spring water and artesian well separately. Result for parameters total suspended solids, pH level, nitrate, phosphate and E.coli shows that the groundwater sources in the area are mainly highly potable. The gathered data also showed groundwater sources that are currently not potable due to the high concentration of different parameters. Thirteen samples out of 29 exceeded the permissible limit with respect to turbidity and 19 groundwater sources for mercury. Nonetheless, some sample points in the study area were generally considered potable. Ten samples for water hardness, 13 for electrical conductivity and 12 points for total dissolved solids. The water quality index of Koronadal City including mercury shows that 65.5% were rated as unfit for drinking and only 34.5% were excellent. However, WQI calculation without mercury shows no sample point exceeded the threshold value and 48.3% of the groundwater sources were rated as excellent.