Identifikasi keluaran air tanah lepas pantai (KALP) di pesisir aluvial Pantai Lombok Utara, Nusa Tenggara Barat

Abstract

ABSTRAK
Penelitian keluaran air tanah di lepas pantai (KALP) merupakan suatu penelitian baru yang saat ini sedang terus dikembangkan. Selain sebagai salah satu pengontrol tingkat salinitas lingkungan biota terumbu, KALP dapat menjadi potensi sumber pencemar dan alternatif penyediaan air bersih di wilayah pesisir dan pantai. Upaya identifikasi telah dilakukan di daerah pesisir aluvial Lombok Utara, Provinsi Nusa Tenggara Barat. Identifikasi KALP dilakukan berdasarkan analisis salinitas, pengukuran hidrogeokimia meliputi sifat kimia fisik air dan unsur penjejak 222Rn pada lokasi terpilih di lintasan laut dan air tanah di daratan. Indikasi kehadiran KALP dijumpai dalam bentuk mata air bawah laut dan rembesan yang dicirikan dengan kandungan salinitas yang rendah dan adanya kandungan 222Rn tinggi. Identifikasi KALP berdasarkan gabungan hasil interpretasi dari metode-metode diatas menunjukkan keluaran air tanah di lepas pantai ini merupakan kendali dari kondisi geologi dan kecepatan aliran air tanah.
Kata kunci: keluaran air tanah di lepas pantai, hidrogeokimia, 222Radon, Pulau Lombok Utara

ABSTRACT
Research on submarine groundwater discharge (SGD) is a new research which is currently being developed in Indonesia. Apart from being one of salinity level controllers for coral environment, SGD may become an alternative water supply potential and also as a pollutant sources in coastal areas. An attempt of SGD identification had been carried out on the alluvial coast of North Lombok, West Nusa Tenggara Province. Identification of SGD was based on salinity analysis and hydrochemical measurement that includes physical chemistry of water property and radon trace elements known as 222Rn at selected locations at sea track and groundwater on land. Indication of the presence of SGD was found in the form of under seawater springs and seepages which are characterized by low salinity content and the presence of high 222Rn content. Identification of SGD which was based on combined interpretation results of the above methods shows that the output of the groundwater in offshore area is a control of geological conditions and the speed of groundwater flow.
Keywords: submarine groundwater discharge, hydrogeochemical, Radon (222Rn), North Lombok island