Identifikasi Intrusi Air Laut Melalui Analisis Fisika-Kimia Air Tanah di Pesisir Selatan Cilacap, Jawa Tengah, Indonesia: Identification of Seawater Intrusion Through Physico-Chemical Analysis of Groundwater in the Southern Coast of Cilacap, Central Java, Indonesia - Shokhib, Maskhiyatus; Irayani, Zaroh; Azmi, Ulil; Ardenti, Ekalia; Aminuddin, Jamrud (Faculty of Fisheries and Marine Science, Brawijaya University, Malang, Indonesia, 2026)
Wilayah pesisir selatan Kabupaten Cilacap berbatasan langsung dengan lautan yang dapat mengakibatkan rentannya kondisi kualitas air tanah. Sumur gali dan sumur bor sebagai sumber air bersih bagi masyarakat berpotensi terdampak intrusi air laut. Intrusi air laut merupakan proses infiltrasi air asin ke dalam akuifer air tawar. Penelitian ini bertujuan untuk mendeteksi potensi intrusi air laut melalui pengukuran parameter fisika-kimia. Pengukuran parameter Total Dissolved Solids (TDS), daya hantar listrik (DHL), dan salinitas dilakukan pada 14 titik sampling yang tersebar di area studi. Data yang didapatkan dari survei lapangan kemudian dianalisis lebih lanjut regresi linear berganda. Hasil penelitian menunjukkan nilai TDS berkisar antara 99–1510 mg/L, dengan dua lokasi (SWI-09 dan SWI-14) menunjukkan nilai di atas 1000 mg/L. Nilai DHL bervariasi antara 199–3020 µS/cm, di mana dua lokasi yang sama memiliki nilai melebihi 1500 µS/cm. Meskipun demikian, sebagian besar sampel masih memenuhi standar air tawar berdasarkan kriteria PAHIAA (Panitia Ad Hoc Intrusi Air Asin) pada tahun 1986. Analisis regresi linear berganda mengungkapkan bahwa jarak dari pantai berpengaruh signifikan terhadap peningkatan DHL (p-value = 0,034), sedangkan kedalaman sumur tidak signifikan (p-value = 0,244). Hasil ini menunjukkan adanya indikasi awal intrusi air laut di lokasi yang sangat dekat dengan garis pantai, namun sebagian besar sumur masih layak digunakan karena masih dibawah nilai baku mutu (DHL <1.500 µS/cm, TDS <1.000 mg/L). The southern coastal region of Cilacap Regency directly borders the ocean, which increases the vulnerability of groundwater quality. Dug wells and bore wells, which serve as clean water sources for local communities, are potentially affected by seawater intrusion. Seawater intrusion is the process of saline water infiltrating freshwater aquifers. This study aims to detect the potential for seawater intrusion through the measurement of physico-chemical parameters. Measurements of Total Dissolved Solids (TDS), electrical conductivity (EC), and salinity were conducted at 14 sampling points distributed across the study area. The data obtained from field surveys were further analyzed using multiple linear regression.The results show that TDS values range from 99 to 1510 mg/L, with two locations (SWI-09 and SWI-14) exceeding 1000 mg/L. EC values vary between 199 and 3020 µS/cm, where the same two locations recorded values above 1500 µS/cm. Nevertheless, most samples still meet the freshwater standards based on PAHIAA (1986) criteria. Multiple linear regression analysis reveals that the distance from the coastline significantly influences the increase in EC (p-value = 0.034), whereas well depth is not significant (p-value = 0.244). These findings indicate early signs of seawater intrusion in locations very close to the shoreline; however, most wells remain suitable for use as they are still below the threshold values (EC < 1500 µS/cm, TDS < 1000 mg/L).