Integration of borehole and vertical electrical sounding data to characterise the sedimentation process and groundwater in Krueng Aceh basin, Indonesia

This research aims to determine the characteristics of sediment and aquifer layers beneath the surface based on borehole data and the Vertical Electrical Sounding (VES) method as well as to map the groundwater protection zone for future generations. Thirty boreholes were analysed to determine sediment grain size and its structure at every depth up to 200 m beneath the surface. Six locations of VES were performed to confirm the presence of groundwater at every depth of lithology. The spatial analysis was used to scrutinize sand to clay ratio distribution of the boreholes data from which map of the groundwater protection zone of the study area was developed. The results reveal that the characters of sedimentation in the Krueng Aceh basin are influenced by terrestrial and coastal processes at a depth of 200 m below modern mean sea-level (MSL). Historically, the sedimentation process beneath 160 m is highly related to the Last Glacial Maximum (LGM) event and sea-level fluctuation in Southeast Asia. The VES findings denote the clayey sands, sands, and gravel strata discovered in borehole functioning as aquifer layers and they are indicated by low resistivity value. The sand to clay ratio distribution mapping indicates that the centre part of the basin is the water resources zone, and it should be protected for future generations.