Arief Rachmansyah

Integrated Resistivity and Ground Penetrating Radar Observations of Underground Seepage of Hot Water at Blawan-Ijen Geothermal Field

Geothermal resource investigation was accomplished for Blawan-Ijen geothermal system. Blawan geothermal field which located in the northern part of Ijen caldera presents hydrothermal activity related with Pedati fault and local graben. There were about 21 hot springs manifestations in Blawan-Ijen area with calculated temperature about 50°C. We have performed several geophysical studies of underground seepage of hot water characterization. The geoelectric resistivity and GPR methods are used in this research because both of them are very sensitive to detect the presence of hot water. These preliminary studies have established reliable methods for hydrothermal survey that can accurately investigate the underground seepage of hot water with shallow depth resolution. We have successfully identified that the underground seepage of hot water in Blawan geothermal field is following the fault direction and river flow which is evidenced by some hot spring along the Banyu Pahit river with resistivity value less than 40 Ωm and medium conductivity.

Water Carrying Capacity Approach in Spatial Planning: Case Study at Malang Area

The Law of the Republic of Indonesia Number 32 of 2009 and 26 of 2007 affirms that need environmental carrying capacity in preparation of regional spatial plans. The Great Malang bypassed 12 sub-watershed which is 4 of them pass 3 regency / city directly. Therefore, it needs an integrated spatial arrangement between the three regions. The purpose of this research is to formulate study of water carrying capacity (WCC) and recommendation for input in spatial planning in Malang area. The results of the water carrying capacity study show that Metro and the Bango Sub-watershed is very worrying because its critical condition has been exceeded before 2015. While the Amprong and Manten sub-waters are still safe until 2030. Key word: Amprong, Bango, Manten, Metro, Sub-watershed, Water carrying capacity

The impact of Kelud Volcano eruption to food security case study: Ngantang district, Malang Regencys

Kelud volcano is one of the active volcanoes in Indonesia. Kelud volcano is located among Malang, Kediri and Blitar Regency. The last eruption occurred on February, 2014. Ngantang District, Malang Regency was the worst affected area with severe infrastructure damage including clean water, roads, and bridges, causing temporary isolation. This led to disturbance in food security that consists of aspects of food availability, food access and food utilization. Food security is a condition related to the supply of food, and individuals’ access to it. This research focuses on achieving household food security by analyzing 1) disaster prone area of Kelud Volcano at Ngantang District after eruption 2014; and 2) food security that consists of the assessment of food availability, food access and food utilization at Ngantang District. This research finds that: 1) Pandansari village and Ngantru village are the worst prone area villages; and 2) The food security analysis shows that Pandansari Village is higly insecure...

INTERPRETATION OF BOUGUER ANOMALY TO DETERMINE FAULT AND SUBSURFACE STRUCTURE AT BLAWAN-IJEN GEOTHERMAL AREA

Gravity survey has been acquired by Gravimeter Lacoste & Romberg G-1035 at Blawan-Ijen geothermal area. It was a focusing study from previous research. The residual Bouguer anomaly data was obtain after applying gravity data reduction, reduction to horizontal plane, and upward continuation. Result of Bouguer anomaly interpretation shows occurrence of new faults and their relative movement. Blawan fault (F1), F2, F3, and F6 are normal fault. Blawan fault is main fault controlling hot springs at Blawan-Ijen geothermal area. F4 and F5 are oblique fault and forming a graben at Banyupahit River. F7 is reverse fault. Subsurface model shows that Blawan-Ijen geothermal area was dominated by the Ijen caldera forming ignimbrite (ρ1=2.670 g/cm3), embedded shale and sand (ρ2=2.644 g/cm3) as Blawan lake sediments, magma intrusion (ρ3=2.814 g/cm3 & ρ7=2.821 g/cm3), andesite rock (ρ4=2.448 g/cm3) as geothermal reservoir, pyroclastic air fall deposits (ρ5=2.613 g/cm3) from Mt. Blau, and lava flow (ρ6=2.890 g/cm3).