| Abstract |
The research site is located 30 km south of Manado city or west of Tondano lake at an altitude of 850 meters above the sea level. The geology of the research site is represented within a geological map by Ganda and Sunaryo (1982). Based on the current geological map, it may be pointed out that the research site is defined as high terrains situated in a small Pangolombian caldera which has collapsed in its center area resulting in the formation of a volcanic group called Tampusu-Linau. The stratigraphy of the area is comprised of young volcanic sediments, which in an older to younger sequence are: Lengkoan, Pangolombian, Kasuratan, Kasuan and Kolovium Formation sediments. The conceptual model of Lahendong geothermal field consists of two reservoirs, that is a shallow reservoir having a depth of 500 - 700 meters and a deep reservoir having a depth above 1500 meters. From such a conceptual model can be observed that the recharge factor holds an important role as a mass supplier to the reservoir. The objective of the research is to determine the amount of recharge into the reservoir by means of an overlay of geologic map, fracture density map, and fluid dynamic map. From the overlay of the various maps, it enables the determination of the cross sectional boundary of the recharge area to obtain the area of research. The amount of recharge from rainfall which infiltrates into the recharge area can be determine by the infiltration amount of rainfall into the area, rainfall data and infiltration coefficient. Based on calculations, it is determined that the amount of recharge in the Lahendong Geothermal Field is 10.3 x 106 m3/year. |