GEOLOGICAL STUDY AND THE DISCHARGE CONTROL OF COLD AND WARM SPRINGS IN WANAYASA AREA, BANJARNEGARA REGENCY, CENTRAL JAVA PROVINCE

• Main Author: Lim Martin, Kenny
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/86713
• Institution: Institut Teknologi Bandung

The cold and warm springs in the Wanayasa area and its surroundings have been utilized by local residents as a water source in their daily activities, so their sustainability needs to be maintained. Studies on geological and hydrogeological conditions is very important for the purpose of water source conservation, but in this area, it is still limited. Therefore, this study is purpose to map geological conditions and identify geological factors that control the emergence of cold and warm springs in the Wanayasa area and its surroundings. The research methods used are consists of literature studies, DEMNAS imagery analysis, field mapping, and laboratory analysis of rock and water samples. Based on the results of the analysis, the geomorphology in the research area is divided into 19 units. The research area is divided into 15 rock units based on the principles of volcanostratigraphy and lithostratigraphy. The geological structures identified in the research area are the Sirukem Right Normal Slip Fault, Balun Right Normal Slip Fault, and Mrawu Thrust Fault. Based on the type of occurrence, the springs in the research area are classified into depression, fracture, and fault springs. Depression springs have a discharge of <1 L/s located on the slope bend, while springs controlled by fractures and faults are classified as fracture and fault springs with a discharge of >1 L/s. The water recharge area is at an elevation of 1600 m based on 18O and 2H isotope analysis. The catchment area is in a lithological condition in the form of pyroclastic rocks with a flat to gentle slope. The discharge area is found at a lower elevation with lithology in the form of alluvial deposits and a gentle slope. The cold springs with TDS values <100 ppm indicate the absence of thermal contamination with a local flow pattern type. Warm springs show a regional flow pattern type characterized by TDS values >1000 ppm, as well as relatively higher dissolved element content. Warm springs circulate from north to south with the heat source interpreted from the remaining volcanic activity of Rogojembangan Volcano, then emerging through the fault planes.