Groundwater Hydrogeochemistry in Bukit Raya and Tenayan Raya, Pekanbaru, Indonesia

Abstract

Pekanbaru is growing rapidly and one of the largest in industry and commercial sector on Sumatera Island. Hydrogeological mapping and major elements in groundwater samples from protected wells were used to determine hydrochemical facies in Bukit Raya and Tenayan Raya sub-districts in Pekanbaru. A total of 14 groundwater samples were collected in May 2017. A Piper Trilinear diagram was employed to evaluate the hydrogeochemical evolution of groundwater. Results show that water table varies from 7.02 to 46.67 m in depth and flow toward the middle of research area which is Sail River. Based on groundwater table, the relationship between groundwater and river water was effluent. Hydrochemical facies of groundwater in the study area are dominated by sodium chloride, calcium chloride, and calcium bicarbonate water type. Dominance of Na+ elements in facies is from the dissolution of Feldspar or Pyroxene in sand, and the Ca2+ element in facies is from the dissolution of Feldspar and Plagioclase in sand. The presence of Cl- element in facies is from salt crystals in rainwater, and the HCO3- element in facies has contact with air and is dominated by rainwater. Lithology conditions in the study area are generally weathered so that the influence of rocks on rainwater is quite high.