Hydrogeology Conceptual Model of Meninting Dam and Its Surrounding Area, West Lombok Regency, West Nusa Tenggara, Indonesia

The Meninting Dam is one of the dams recently built in West Lombok, Indonesia. Hydrogeologically, this dam was built on the Mataram-Selong Groundwater Basin, which is known to be a highly productive aquifer. However, in this area, no extensive research in terms of hydrogeological conditions has been conducted. Therefore, the objective of this research is to present a conceptual model of the hydrogeology of the Meninting Dam and its surrounding area. This study was carried out by collecting primary and secondary data on the geological, hydrological, and hydrogeological conditions in the research area. Results show that there are two layers of unconfined aquifer, one layer of aquitard, and one layer of confined aquifer in this area. The unconfined aquifer is built by layers made up of pebbles, sand, clay, gravel, and boulders, but also a layer of pumiceous tuff with a thickness up to 40 m and a hydraulic conductivity value between 10-1 mm/s and 5x10-2mm/s. The confined aquifer is composed of pumiceous tuff and has a thickness range of up to 100 m and a K value of about 5 x 10-3 mm/s. Between unconfined and confined aquifers, there is a thick layer of aquitard made up of laharic breccia.