This study investigates flooding within the campus of the Federal College of Education (Technical), Omoku, and its environs using integrated geophysical methods. Geo-electric resistivity (VES) and Electrical Resistivity Tomography (ERT) were employed to characterize subsurface properties that influence water retention, drainage, and flooding susceptibility. The VES analysis delineated four geo-electric layers with resistivity values ranging from 57.9 to 32,936.7 S2m, revealing significant subsurface heterogeneity. The topsoil (layer 1) exhibited variable resistivity (86.7-824.4 S2m), indicating mixed sandy and clayey materials with poor drainage in low- resistivity zones. The second and third layers demonstrated variable thickness and resistivity, reflecting saturated zones prone to water retention and areas with better drainage properties. The fourth layer, likely compact bedrock, exhibited high resistivity, acting as a barrier to water flow and contributing to surface runoff. Secondary geo-electric parameters including reflection coefficients, transverse resistivity, longitudinal resistivity, and anisotropy, provided additional insights. Low resistivity and high anisotropy zones indicated water-saturated or clay-rich materials associated with flood-prone areas. High resistivity and low anisotropy corresponded to better-draining zones with sandy or gravelly materials. ERT profiles complemented the VES results by mapping lateral and vertical variations in resistivity. Low-resistivity zones in the upper subsurface were linked to water- saturated soils, obstructing drainage and increasing flood risk. High-resistivity regions indicated less permeable materials that could exacerbate runoff and surface water accumulation. The study concludes that the interplay of subsurface heterogeneity, saturated zones, and impermeable layers significantly influences flooding in the area. The findings provide critical data for flood risk management and infrastructural planning, highlighting the need for effective drainage systems and soil stabilization measures in vulnerable regions.

Bengkulu Province, Indonesia, is one of regions prone to earthquake hazards. Daily seismic activity, albeit minor, and imperceptible to humans is common place. Data from the Meteorology, Climatology, and Geophysics Agency reveals an average of eight earthquakes per week. Earthquakes often trigger subsequent disasters such as tsunamis, landslides, and liquefaction. However, liquefaction-related phenomena are often overlooked in researchs, particularly concerning subsurface layers. A notable event occurred on September 12th, 2007, when a powerful 8.6 magnitude earthquake struck Indonesia, causing significant damage, particularly in Bengkulu City. This was followed by a liquefaction disaster in Tanah Patah Village, Bengkulu City. Consequently, the aim of this study is to assess the subsurface conditions in the liquefaction-affected area using geophysical techniques, including microtremor and geo-electric surveys. The data was analyzed to evaluate soil conditions in the affected zone. The resistivity values indicate a predominance of water and sand mixtures at depths of 0 - 20 m (ranging from 1.46 to 15.5 Omegam in Geo_TP-1 and from 4.64 to 15.1 Omegam in Geo_TP-2). These conditions can facilitate processes like condensation and water flow, leading to sand compaction and increase susceptibility to liquefaction. The findings reveal that loose sand dominates the subsurface layers, rendering them highly vulnerable to liquefaction during intense seismic events. Furthermore, the environmental characteristics of the studied area exacerbate its susceptibility to liquefaction. This study provides a comprehensive analysis of soil conditions in the liquefied zone of Bengkulu City.