Pengaruh Intrusi Air Laut terhadap Karakteristik Air Sumur Bor dan Konvensional di Desa Dusun 1 Pantai Cermin Kanan Sumatera Utara

Abstract

Seawater intrusion is a serious threat to groundwater quality in many coastal areas, particularly in Indonesia, an archipelagic country that is highly vulnerable to rising sea levels and excessive groundwater extraction. This study aims to examine the impact of seawater intrusion on the quality of borehole and conventional well water in Dusun 1 Pantai Cermin Kanan Village, North Sumatra. Sampling was carried out at five borehole well points (10–15 m deep), five conventional well points (4–12 m), and seawater as a comparison. The measured parameters included electrical conductivity (EC), pH, total dissolved solids (TDS), salinity (Na content), and manganese (Mn) levels. The results show that borehole well water generally has better quality with a near-neutral pH (6.58–7.27), low TDS (53–75 mg/L), and moderate salinity (25–36 g/L). In contrast, conventional well water tends to be more acidic (6.25–6.62), has higher TDS (74–105 mg/L), and at several points shows a spike in salinity and very high Mn levels despite being more than 2,000 m from the coastline. These findings indicate that seawater intrusion significantly affects shallow, less-protected conventional wells, while deeper borehole wells, although relatively safer, still show signs of saltwater seepage. This study emphasizes the importance of regular management of groundwater extraction and improving well construction standards to control seawater intrusion and protect the health of the community and the agricultural sector in coastal areas