Karakteristik Hidrogeologi dan Hidrogeokimia DAS Tempuran Lereng Barat Kompleks Gunungapi Bromo-Tengger

Abstract

Abstrak Lereng bagian barat Gunungapi Bromo meiliki peranan penting dalam penyediaan air untuk masyarakat disekitarnya. Penggunaan air tanah cukup intensif baik domestik, pertanian, dan industri pada lereng bagian barat Gunungapi Bromo. Lerang bagian barat bagian barat Gunungapi Bromo belum pernah dilakukan kajian detail baik potensi, kualitas, dan imbuhan air tanah. Kajian tersebut di tujukan untuk mengetahui kondisi air tanah di lereng bagian barat Gunungapi Bromo supaya dapat dimanfaatkan secara berkelanjutan. Metode yang digunakan dalam penelitian ini terdiri atas pengamatan batuan, pengukuran muka air tanah, pengukuran kimia air tanah TDS, pH, EC, dan suhu, analisis geokimia berdasarkan diagram piper, diagram fingerprint, dan diagram kurlov, analisis isotop asal usul air tanah dan imbuhan air tanah. Litologi di area kajian terdiri atas endapan pasir kerikilan, endapan pasir, batupasir, konglomerat, breksi laharik, lapilli tuff, tuff, breksi, dan lava andesit. Nilai TDS, pH, Suhu, dan EC di DAS Tempuran semakin meningkat dari hulu ke hilir. Pola aliran air tanah pada DAS Tempuran secara umum mengalir dari arah selatan menuju utara. Satuan lava dan breksi andesit merupakan akuifer, lava andesit dan breksi andesit merupakan akuiklud, jatuhan piroklastik merupakan akuifer, dan tuf dan lapilli tuf merupakan akuitard. Tipe air tanah pada DAS Tempuran didominasi oleh tipe kalsium bikarbonat (diagram piper) dan kalsium magnesium bikarbonat (diagram kurlov), dan diagram fingerprint terdapat 3 sistem air tanah. Sampel air tanah di DAS Tempuran keseluruhan berasal dari air meteorik. Imbuhan air tanah di DAS termpuran berasal dari elevasi 430-805 mdpl. Daerah imbuhan air tanah terdapat di Kecamatan Pasepran, Puspo, dan Tutur. Air tanah di area kajian secara kualitas dan kuantitas tergolong sangat baik.Abstract The western slopes of Mount Bromo have an important role in providing water for the surrounding community. Groundwater use is quite intensive, both domestically, agriculturally, and industrially, on the western slopes of Mount Bromo. The western slope of Mount Bromo has never had a detailed study of its potential, quality, and groundwater recharge. The study was aimed at determining the condition of groundwater on the western slopes of Mount Bromo so that it can be used sustainably. The methods used in this research consist of rock observations, measurements of groundwater levels, measurements of groundwater chemistry (TDS, pH, EC, and temperature), geochemical analysis based on Piper diagrams, fingerprint diagrams, and Kurlov diagrams, isotope analysis of the origin of groundwater, and recharge. groundwater. The geology in the study area consists of gravelly sand deposits, sandstone, conglomerate, laharic breccia, lapilli tuff, andesite breccia, and andesitic lava. The TDS, pH, temperature, and EC values in the Tempuran watershed increase from upstream to downstream. The groundwater flow pattern in the Tempuran watershed generally flows from south to north. Units of lava and andesite breccia are aquifers; andesite lava and andesite breccia are aquicludes; pyroclastic falls are aquifers; and tuff and tuff lapilli are aquitards. The groundwater types in the Tempuran watershed are dominated by calcium bicarbonate (Piper diagram) and calcium magnesium bicarbonate (Kurlov diagram), and in the fingerprint diagram, there are 3 groundwater systems. The entire groundwater sample in the Tempuran watershed comes from meteoric water. Groundwater recharge in the purest watershed comes from an elevation of 430–805 meters above sea level. Groundwater recharge areas are in the Pasepran, Puspo, and Tutur Districts. The study area’s groundwater quality and quantity are rated as very good