Groundwater Facies in the South Parts of Tegal-Brebes Groundwater Basin

Abstract

The southern part of the Tegal Brebes Groundwater Basin has various rock units originating from the volcanic activity of the Slamet Volcano. The groundwater interacts with these rocks and influences the hydrogeochemical process that may alter its chemical components. The objective of this research is to assess the relationship between groundwater chemistry facies and the rock aquifer. The finding of this research will help us better understand how hydrogeochemical processes work, perform thorough research, and determine the water quality. The groundwater characteristics are determined based on the chemical composition of the water taken from the citizen’s dug wells and springs. These samples were collected to represent a difference in rock’s formation, namely Linggopodo Formation, Tapak, and Slamet Undifferentiated Volcanic Rock. The analysis of the Piper diagram shows that all the samples fall into one facies: the calcium bicarbonate type (Ca-HCO3). The groundwater’s physical and chemical properties in the study area indicate that groundwater quality has not interacted much with lithology and is still greatly influenced by meteoric water. The groundwater facies are dominated by the Ca-HCO3, a characteristic of shallow groundwater and local water flow systems.