GEOLOGY AND HYDROGEOLOGY OF RADEN SURYO NATIONAL FOREST PARK, ARJUNO-WELIRANG VOLCANO, EAST JAVA

• Main Author: Ahmad Asvandiari, Adam
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/69718
• Institution: Institut Teknologi Bandung

The research area is located in the northern part of the Raden Suryo National Forest Park which is part of the Nature Conservation Area (KPA) within the Arjuno-Welirang Volcanic Complex. This volcanic complex is a stratovolcano with a composite cone of Quaternary age in which there are Arjuno-Welirang geothermal prospects. Geothermal exploration and development activities in this prospect are hampered by the issue of forest and water conservation. This study aims to identify geological conditions that control hydrological patterns and hydrogeological elements such as infiltration and discharge areas, control of thermal manifestations, types of aquifers, and interpretation of geothermal system boundaries, the results of which are expected to be taken into consideration for geothermal prospects and nature conservation in the area. The methods used are literature studies, digital elevation model analysis, and hydrogeochemistry. Digital elevation model analysis was used in interpreting slope maps, drainage patterns, geological structures, geomorphology, and volcanostratigraphy. Analysis of twelve cold springs and five hot springs on the ternary diagram of Cl-HCO3-SO4 and piper diagram were used to determine the ionic composition of spring manifestations. Maps of slope, drainage patterns, spring distribution, and chemical composition of water are used to determine groundwater flow pattern, recharge, discharge, and run-off areas. Geological structure and lithology maps were used to identify the control of cold and hot spring manifestation. Geological maps from the literature are used to determine rocks that can become aquifers, while volcanostratigraphy maps and chemical composition of springs are used to help delineate the boundaries of geothermal systems. Based on this research, the main geological condition that controls the hydrological pattern is the Arjuno-Welirang Volcano which is a stratovolcano with composite cone. This condition causes the recharge area to be placed in topographic highs with a relatively gentle slope, discharge areas are placed in topographic lows, while areas with steep slope will become run-off area with local groundwater flow. Steep slope and geological structure act as a control of thermal manifestation. The type of aquifer in the area is rare groundwater productivity to locally productive aquifer with the lithology consisting of basalt to andesite. The approximate area of the geothermal system is inside the Welirang Crown.