Human activities in lake catchments and waterways have a considerable detrimental impact on lake ecosystems, including processes such as eutrophication and siltation. The study’s objective was to gain a deeper understanding of the impact of anthropogenic activities on water quality, pollutant diffusion in Lake Batur waters, and the level of eutrophication. Water samples from nine sampling locations (SLs) in Lake Batur, Indonesia, were collected and examined for physical, chemical, and biological properties. The study revealed that Lake Batur receives a considerable quantity of anthropogenic waste on an annual basis, including 14,776 tons of organic matter (COD), 1,486 tons of total nitrogen (TN), and 461 tons of total phosphorus. The primary source of these effluents was autochthonous effluents from FNC operations, which constituted 74.4% of the COD, 86.6% of the TN, and 85.6% of the TP. The distribution of effluents from community activities across the ECW, WCW, and MLW resulted in variability in the concentrations of total suspended solids (TSS), nutrients, chlorophyll-a (Chl-a), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and fertility levels in the nine LS. The Chl-a/COD ratio indicated that SL 1, situated in the ECW, exhibited the highest fertility, whereas SL 5, located in the MLW, demonstrated the lowest. The fertility level was constrained by phosphorus, as evidenced by a TP/TN ratio exceeding 12 in eight SLs. The Trophic Status Index (TSI) was calculated using Carlton’s formula, and the results indicated that, with the exception of SL 2, which was categorized as mesotrophic, the remaining eight SLs were eutrophic. Given that the Trophic Status Index (TSI) (Chl-a) is greater than the TSI (TP), it can be reasonably concluded that phosphorus is the limiting factor for algal development in seven of the nine SLs. The TSI (Chl-a) values for some SLs (SLs 2-4) were observed to be lower than the TSI (SD) values, indicating that non-algal particles may have exerted a greater influence on lake water clarity.

Landslides pose a significant natural hazard requiring cost-effective, sustainable mitigation strategies. Nature-based solutions utilizing vetiver (Chrysopogon zizanioides) demonstrate considerable potential due to its deep, dense root system, which enhances soil reinforcement. This study examines the effects of growth medium composition and NPK fertilization on the root mechanical properties, biomass accumulation, and vegetative growth of vetiver under controlled greenhouse conditions. The planting medium comprised landslide-affected soil mixed with compost in varying proportions, combined with different NPK fertilizer levels. Root tensile strength was measured to assess mechanical performance, while biomass and vegetative parameters were evaluated to determine growth responses. Results indicate that both growth medium composition and fertilization significantly influence biomass production, root diameter, and tensile strength. The highest biomass (178.33 g) was recorded under T80P20N7.5, while the greatest root diameter (1.47 mm) and tensile strength (21.9 MPa) were observed under T100P0N0. These outcomes suggest a trade-off between biomass production and mechanical reinforcement. Overall, optimizing soil amendments and nutrient inputs enhances vetiver’s bio-reinforcement capacity, supporting its application in sustainable slope stabilization and landslide mitigation.

Earthquake-induced landslides represent a critical threat to transportation infrastructure in tectonically active mountainous regions, particularly in tropical volcanic settings where weak, highly weathered geomaterials dominate. This study develops an integrated framework that directly links physically based seismic threshold modelling with real-time landslide monitoring and operational early warning. The approach is demonstrated in the Cugenang area of Cianjur Regency, West Java, Indonesia, which was severely impacted by the moment magnitude (Mw) 5.6 earthquake in 2022. Slopes composed of highly weathered pyroclastic deposits [Plasticity Index (PI) = 54–68%; porosity > 60%] exhibit low shear strength and high sensitivity to seismic loading. Limit equilibrium analysis using the Morgenstern–Price method that combines the influence of seismic loading and groundwater conditions suggests that a horizontal seismic coefficient (kh) of approximately 0.06, corresponding to a Peak Ground Acceleration (PGA) of about 0.12 gravitational acceleration (g), is a critical threshold for initial landsliding. This comparatively low threshold challenges commonly reported values and demonstrates that slope failure in tropical volcanic terrains can occur under moderate ground shaking, reinforcing the need for site-specific hazard characterisation. The derived thresholds are operationalised within a multi-sensor early warning system integrating Micro-Electro-Mechanical Systems (MEMS) accelerometers and inclinometer measurements. Three hazard levels—Normal (<0.06 g), Alert (0.06–0.12 g), and Emergency (≥0.12 g)are combined with deformation thresholds [30 mm] to capture progressive failure processes and minimise false alarms. By coupling geotechnical modelling and real-time monitoring, this study provides a transferable and scalable framework for enhancing infrastructure resilience in landslide-prone regions.