Hydrogeochemical characteristics analysis of groundwater along coastal area of Ujong Pancu, Aceh Besar regency

Abstract

Groundwater is the primary source of fresh water for communities in the coastal area of Ujong Pancu, Peukan Bada, Aceh Besar. However, limited assessments of its suitability for domestic use, combined with geological conditions dominated by high-porosity alluvial deposits (Qh), increase its vulnerability to contamination. Therefore, this study aims to analyze the hydrogeochemical characteristics and evolution of groundwater and to identify the controlling geochemical processes. A total of 10 groundwater samples were collected from dug wells and analyzed for major cations (Na, K, Ca, and Mg) and anions (Cl, SO₄, and HCO₃). The results were interpreted using Stiff and Piper diagrams to determine hydrochemical facies and groundwater evolution. The results show that groundwater is dominated by Ca–Mg–HCO₃, mixed facies, and Na–HCO₃–SO₄. The evolution of groundwater chemistry indicates carbonate mineral dissolution and cation exchange processes, in which Ca–Mg is progressively replaced by Na along the groundwater flow path. Several samples exhibit balanced Ca and HCO₃ concentrations, indicating meteoric water characteristics. In conclusion, groundwater hydrogeochemistry in the Ujong Pancu coastal area is primarily controlled by water–rock interaction and internal aquifer processes.