FLOW PROCESS AND GROUNDWATER INTERACTION BASED ON HYDROGEOCHEMICAL AND ISOTOPE ANALYSIS IN SOUTHEAST WAWONI, KONAWE ISLANDS, SOUTHEAST SULAWESI

• Main Author: Aji Kusumah, Purnama
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66872
• Institution: Institut Teknologi Bandung

The research area is located in Southeast Wawoni, Wawoni Island, Konawe Islands District, Southeast Sulawesi Province. The aims of this study were to (1) identify the hydrogeochemical conditions of the springs in the study area, (2) determine the source of dissolved ions, (3) determine the estimated recharge area of the springs, and (4) determine the potential disturbance from mining to local groundwater. The method used is a collaboration between hydrogeology and geomorphology. Based on the geomorphological aspect, an analysis of bifurcation ratio (Rb) and fault fracture density (FFD) was carried out. Based on the hydrogeochemical aspect, the physico-chemical properties of groundwater were tested in situ and laboratory tests in the form of major ion testing, REE, and stable isotopes 18O, 2H and 13C. Based on the Rb and FFD values analysis, joints and faults influenced the overall formation of the springs. There are 5 hot springs in the study area. The hot springs has a different composition and different physico-chemical parameter values with the cold springs. The hot springs generally have a high temperature, high TDS, high EC, high salinity, and relatively low in pH value. The presence of the hot springs is also influenced by geothermal activity which is characterized by the presence of a slight smell of sulfur steam around the hot springs. In general, the springs in the study area belong to the magnesium bicarbonate facies with the dominant enrichment of Ca2+, Mg2+, and HCO3- elements. Another process that occurs in all springs is the silicate hydration process characterized by the enrichment of the composition ? 2H and the depletion of ? 18O. In general, the stable isotope values ?18O and ?2H have a light mass, this may be due to the influence of excess humidity caused by the low temperature in the study area. The CO2 degassing process also accompanies several springs in the study area. Dissolved ions Ca2+, Mg2+, and HCO3- were interpreted as dissolved minerals from limestone and metamorphic limestone in the study area, while Na+ and K+ were interpreted from local ultramafic and metamorphic rocks. The recharge area of SP03 is estimated to be in the hills to the north-northeast with an elevation of 77-329 masl, while the estimated recharge area of SP09 is at an altitude of 142-347 masl on the hill to the north of the spring location. Disturbances in the quality and quantity of groundwater can occur after mining activities are carried out at the Nickel Mining PIT of PT. X. In general, the overall formation of the springs were influenced by joints and faults, and also have a strong interaction with metamorphic limestone, limestone, and ultramafic rocks.