Recharge Elevation of Hot Spring Study in the Mt. Muayat at the Kotamobagu Geothermal Field, North Sulawesi, Indonesia Using the Stable Isotope O-18 and H-2

Abstract

Water samples of Mt. Muayat consisting of hot spring and river water were analyzed stable isotope. Rain water was also collected using a rainwater collector of open air type from five locations with elevations ranging from 556m to 1500m during March 2010 to June 2010. Six hot spring waters of Mt. Muayat have shift of less than 2‰. This implies that the origin of hot spring water is mainly meteoric water. The meteoric water has recharged to the ground of Mt. Muayat flowed through the shallow aquifer at low temperature to the west or south west. The pathway of water in the shallow aquifer may be through the high permeability in pumice tuff or can through the fault before discharged to the hot springs in the lower elevation in Liberia, Bongkudai, Bilalang and Wangga villages. The sources of hot spring recharge in the Kotamobagu was estimated by evaluating the isotope of local meteoric water and hot springs with neglected effect of evaporate located from 893m to 1227m above sea level of Mt. Muayat.