Hidrogeokimia Air Tanah dalam (Deep Well) Menggunakan Metode Piper dan Diagram Stiff Studi Khusus: Daerah Kecamatan Medan Belawan, Kota Medan, Provinsi Sumatera Utara

Abstract

The average increase in population growth in Belawan City from 2010 to 2021 has a significant increase, reaching 1.05% every year, and has an effect on increasing groundwater use. The impact of excessive groundwater exploitation causes seawater to advance towards the land which results in a lot of empty space in the aquifer so that there is a difference in groundwater level which is lower than sea level, this is an indication of sea water intrusion. Based on this, this study aims to (1) analyze the hydrogeochemical type or facies of groundwater and (2) analyze the hydrogeochemical evolution of groundwater. The method of sampling deep groundwater (deep well) is a production well used to determine the quality of groundwater in the research area. The research area is administratively located in the Belawan area, Medan Belawan District, North Sumatra Province. The methodology used to process the data in this paper is a qualitative method with the Stiff Diagram and Piper Diagram methods. Types or hydrogeochemical facies of groundwater in the research area of Medan Belawan District are Mg-HCO3, Ca-HCO3, Mg-Cl, and Ca-Cl, the dominant groundwater facies is CaHCO3 followed by Mg-HCO3. Groundwater in this research area is bicarbonate (I) water. The results of the evolution of the hydrogeochemical facies that occurred indicated an indication of a seawater intrusion process because Cl was found, and there was one point (point 11) which indicated low-level seawater intrusion. Based on the results of the piper diagram and the stiff diagram, it is stated that the dominant elements are Ca, Mg, and HCO3, it indicates the presence of lime or limestone deposits in the groundwater. The high alkali content can cause water hardness. One of the treatments for treating water hardness is an ion exchanger