Groundwater-surface water interactions of Ciliwung River streams, segment Bogor-Jakarta, Indonesia

CiliwungRiver water quality and its vicinity have been continuously degraded with the increasing population. The objective of this research is to understand the association between river and groundwater, and the water quality profile. Field measurements ware taken from 65 stations from Bogor to Jakarta. Water level, temperature, pH, and TDS were measured to build the water flow map and hydrochemical profile. Small-scale geoelectrical survey was conducted at five locations to capture the aquifer's geometry. We identified three types of stream relationships between river and groundwater: effluent from Bogor to Katulampa (Segment 1), perched at the University of Indonesia (UI) area (Segment 2), and influent from UI to Muara (Segment 3), with low gradient from <0.1 to 0.3. The temperature profile of river and groundwater shows similar pattern as well as TDS profile. All similarities support close connection of river and groundwater. The increasing TDS towards downstream shows increasing enrichment and contamination. The erratic pattern of pH indicates chemical instability due to high contamination. This study highlights the benefit of understanding the hydrodynamic relationship between river water and groundwater. Such interaction triggers water quality exchange between both water bodies. Therefore, a similar study should also be done on other riverbanks in Indonesia to protect water quality.