Characteristic aquifer in volcanic terrains: case study at Caldera Lake Maninjau, West Sumatera - Indonesia

Abstract

Lake Maninjau is a caldera lake with volcano-tectonic type. Lake Maninjau composed of andesit and tuff formation. The existence of water was sourced by rain and ground water. The aquifer units consist of local productive aquifers and rare ground water aquifer. The purpose of this research is to know the characteristic of aquifer in volcanic terrains support water stability in lake. Geoelectric measurements with Wenner configuration were obtained to know subsurface resistivity which a device used were IRES T300f, used RES2DINV software. The results showed that characteristic of aquifer divided into two areas, rare aquifer and productive aquifer. Productive aquifer with average 21.2 – 213 ohm meter, located at Tanjung Sani (elevation 462 m) had similar with Batang River (elevation 701 m). Rare aquifer with average value 48.4 – 436 ohm meter located at Hamka School (elevation 632 m) and Lawang Park with (elevation 1,294 m). The results of geoelectric reconstruction revealed that volcanic terrains around Lake Maninjau were dominated by rare groundwater aquifer, where capable to keep groundwater in small volume. Further, Fault with northwest – southeast as the general direction were considered to drain water through volcanic terrains.