Aquifer characteristic and groundwater hydrochemistry around South Cipete, DKI Jakarta Province, Indonesia

Abstract

South Cipete area is a highly populated area, where the extraction of groundwater is very intensive, so that the allocation of groundwater has decreased in term of quality and quantity. The purpose of this study is to determine the type of aquifer and groundwater hydrochemistry. Research methods are including field observations, groundwater sampling, physical properties measurement and chemical analysis of the main ions. Based on the northwest-southeast cross section of lithology log, the aquifer types are: stressed aquifers composed of silt and sandstones; semi-stressed aquifers composed of clays and conglomerates at depths of 10 m to -15 m. From the southwest-northeastern cross section, the type of aquifer is: stressed aquifer composed of sandstones with clay; free aquifer buried by backfill materials and silt soils; and semi-stressed aquifers, surrounded by silt and clay sandstones. at the depths of ± 23 m to ± 3 m. Groundwater hydrochemistry in the sample SG/02, SG/04, SG/08 the dominant cations and anions are Na+ + K+ with a value of 56.56%; 57.13%; 25.03% and HCO3- at 26.91%. While in sample SG/06, SG/07 the dominant cations and anions are Mg2+ at 25.81%; 24.52% and anions SO42- at 32.70%; 30.96%.