Research conducted in Pomalaa Subdistrict, Kolaka Regency, Southeast Sulawesi, aimed to identify the potential and characteristics of groundwater in an area with complex geological conditions, dominated by ultramafic and sedimentary rocks. To achieve this objective, a multidisciplinary approach was used, including geological and hydrogeological mapping and direct geoelectric testing in the field. One of the main methods used in this study was a geophysical technique called Electrical Resistivity Tomography (ERT), which is capable of producing two-dimensional subsurface images based on variations in the electrical resistivity of soil and rock. The analysis results show that ultramafic rocks in this region have the potential to be free aquifers, with moderate to high hydraulic conductivity values, making them potentially usable as a source of clean water for the domestic needs of the local community. Meanwhile, the southwestern zone, which is composed of sedimentary rocks, shows the presence of a confined aquifer with high permeability and a relatively low water table, making it a more accessible source of groundwater. The integration of all geological, hydrogeological, and geophysical data provides a comprehensive picture of the distribution and quality of groundwater in the Pomalaa region. These findings provide a strong scientific basis to support strategies for the conservation and sustainable use of groundwater resources, as well as to make.
Pengelolaan lapisan tanah penutup yang mengandung material Berpotensi Membentuk Asam (PAF) dan Tidak Membentuk Asam (NAF) sangat penting untuk mencegah pembentukan air asam tambang (AMD). Penelitian ini bertujuan untuk menganalisis distribusi materi PAF dan NAF berdasarkan karakteristik litologi dan merancang mekanisme penimbunan lapisan tanah penutup berdasarkan SNI 7280:2022. Data diperoleh dari 90 titik lubang bor di area PT X, Kutai Timur. Litologi didominasi oleh batupasir dan batulempung (PAF). Total volume lapisan tanah penutup adalah 185.493.800 bcm, dengan 66,67% PAF dan 33,33% NAF. Desain penimbunan menggunakan pendekatan enkapsulasi (konfigurasi blok NAF-PAF-NAF 1-3-7) untuk mengisolasi PAF dari paparan udara dan udara. Faktor Keamanan (FK) yang dihitung dengan metode Bishop adalah 1,545, yang menunjukkan kemiringan yang stabil.
Groundwater pollution is common in densely populated areas due to the high discharge of domestic as well as agricultural waste. As a result, nitrate is one of the pollutants that is commonly found within the affected groundwater system. Yogyakarta is especially vulnerable to nitrate pollution due to the co-occurrence of rapid urban expansion and agricultural activities. High nitrate concentration in groundwater leads to many adverse effects on the environment, as well as human health. Therefore, this research was conducted to measure the capacity of indigenous aerobic nitrate-reducing bacteria found within the groundwater in Yogyakarta as a potential agent for in-situ bioremediation. A total of 19 indigenous bacteria were isolated from groundwater samples in Yogyakarta and were tested for their nitrate reduction activity. Two of the hight efficient isolates in reducing nitrate aerobically were then measured for their nitrate reduction activity every 24 hours within a 3-day incubation period. The phenotypes of the two bacteria isolates were characterized through the observation of cell morphology, colony morphology, and biochemical tests. Out of the two bacteria isolates, bacteria isolate 1 with similar characteristics to Pseudomonas sp was the most efficient in reducing nitrate, with 95.38% of total nitrate removed and a nitrate reduction activity of 40.67 mgL−1h.
Tieng village and its surrounding areas in Kejajar District, Wonosobo Regency, are identified as regions with a relatively high risk of landslide hazards. This research aims to examine the geological conditions influencing landslide occurrences and to develop a landslide susceptibility zonation map within the study area. Methods of landslide mapping using statistical method weight of evidence (WoE), with parameters including slope, lithology and grade of weathering, distance from lineaments, distance from rivers, and land use. All parameters were classified into several class and spatially processed using ArcGIS software. Then, these maps were overlaid and analyzed based on contrast weight values to produce the final landslide susceptibility zonation map. The resulting susceptibility map categorized into four zones: very low, low, medium, and high landslide susceptibility. The very low landslide susceptibility zone is generally found in the eastern part of the area, the low susceptibility zone is in the western and eastern parts, the medium susceptibility zone occurs in the eastern and southern parts, while the high susceptibility zone is distributed in the southeastern, central, and eastern parts of the study area. The parameters that have the most influence on landslide susceptibility in the research area based on their level of influence from strongest to weakest are land use, distance from lineament, distance from river, lithology and grade of weathering and slope. The accuracy of the landslide susceptibility map was assessed using the Success Rate Curve (SRC) and Prediction Rate Curve (PRC) validation. The Area Under Curve (AUC) values obtained from the SRC and PRC analyses were 0.765 for SRC and 0.741 for PRC, respectively, indicating a good level of model performance.
Mandalay region lies very closed to the dextral Sagaing fault. In the historical record, several earthquakes happened in and around Mandalay region from the beginning of the year of 1400. Among them the most distinct event is the Sagaing earthquake struck on July 16, 1956. This research mainly focuses on results of microtremor survey at 143 sites and 25 data from the boreholes for determination of sediment thickness characteristics and strong ground motion analysis in Mandalay region. For the accurate prediction of earthquake ground motions, the investigation of three elements in its process, namely the source, path, and site effects, is crucial, and their accuracy and reliability should be evaluated. The subsurface profiles, predominant periods, shear wave velocity structures and information about sediment thickness or depth of engineering bed rock were evaluated based on data from boreholes, microtremor survey and laboratory results, combining with inversion program. The shear wave velocity of the top layer is Vs ≤ 190 m/s. The spectral amplitudes of the estimated strong ground motions were smaller at around 0.5 Hz and larger at around 3 Hz in Mandalay region. The peak ground acceleration becomes more than 0.8 g in some areas, which causes severe damage for buildings in high probability.
