This study presents a multi-decadal assessment of glacier change in the Sara Umga Watershed (SUW), between the Parvati and Chandra basins. The region receives a majority of its annual precipitation from Indian Summer Monsoon (ISM) and a comparatively lower share contributed by winter Mid Latitude Westerlies (MLW). Using multi-temporal satellite data, we quantify changes in glacier length, area, surface velocity, elevation, debris cover, ice cliff dynamics, and high-faltitude lakes, supplemented by long-term climate trend analysis. A total of 54 glaciers (>0.05 km 2) were mapped, covering 128.38 ± 2.98 km 2 in 2024, of which 24.84 ± 1.15 km 2 comprised debris-covered ice. Between 1994 and 2024, total glacier area declined by 4.54 ± 0.04 km 2 (0.15 ± 0.001 km 2 yr −1), while debris cover expanded to 24.84 ± 1.15 km 2 (0.37 ± 0.09 km 2 yr −1). Frontal retreat rates for the five major glaciers ranged from ∼12 to 26.2 m yr −1. The largest glacier, Sara Umga (GL01), exhibited a mean surface velocity of ∼23.4 m yr −1. Elevation-change analysis reveals pronounced spatial heterogeneity in glacier thinning, with maximum surface lowering concentrated in the lower, debris-covered ablation zone (3900–4400 m a.s.l.; −1.22 ± 0.95 to −1.67 ± 0.39 m yr −1, locally exceeding −3.0 m yr −1), diminishing thinning at mid-elevations, and near-equilibrium conditions across the accumulation area of GL01 (−0.07 ± 0.54 to 0.06 ± 0.33 m yr −1). Zones of higher thinning and flow attenuation coincide with dense ice-cliff and lake development, indicating strong melt-dynamics coupling. Climate analysis (1901–2024) shows significant winter warming (0.01 °C yr −1) and declining Mid-Latitude Westerly (MLW) dominated winter precipitation (−0.160 mm yr −1), alongside increasing pre- (0.354 mm yr −1) and post-monsoon (0.070 mm yr −1) precipitation. These findings demonstrate that changes in debris-covered Himalayan glaciers cannot be inferred from frontal retreat alone. Instead, coupled changes in thickness, velocity, surface morphology, and climate trends govern long-term glacier response and hence should be studied alongside.
Lava tubes are increasingly studied for their potential as natural shelters during the exploration of rocky planets. This paper provides a comprehensive volcanological review of terrestrial lava tubes, focusing on their dimensions, age, emplacement mechanisms, internal textures, and their relationships with lava flow surface morphologies and compositions. Additionally, we assess the compositional and rheological controls on lava tube formation, including the possibility of a rheological threshold required for tube development. Terrestrial examples offer a crucial framework for interpreting volcanic terrains on other planetary bodies and for understanding the formation and evolution of extra-terrestrial lava tubes. We examine the processes linking the internal features of lava tubes to the surface structures of their parent lava flows, with the aim of reconstructing flow field emplacement dynamics. This approach aids in identifying the locations and pathways of shallow, hidden lava tubes using surface morphology alone. However, the relationship weakens for deeper tubes formed within thick lava flow fields emplaced over months or years, where surface structures mainly record the final, typically low-discharge rate phase of an eruption. Accessing deep tubes would therefore provide direct insights into the early stages of lava flow field development. We further discuss volcanic hazards associated with active lava flow fields that contain lava tube systems, as well as post-emplacement stability, conservation, and the potential for public use of lava tube caves as geo-heritage sites. The volcanological processes summarized here provide essential tools for identifying, interpreting, and utilizing lava tubes both on Earth and on other effusive, basaltic volcanic bodies in the Solar System.
Hydrous semi-closed pyrolysis was performed to clarify how water pressure (WP, 50–1,200 bar) and lithostatic pressure (LP, 125–2000 bar) control molecular composition and stable carbon isotopes of thermogenic gas from lacustrine Type I and Type III kerogen, and to verify whether pressure triggers carbon isotope reversal. Immature calcareous shale (Type-I, Ro = 0.40%) and low-mature carbonaceous mudstone (Type-III, Ro = 0.68%) from the Liaohe Shahejie Formation were heated at 450 °C and 480 °C, respectively, with a constant pyrolysis duration of 10 h. All produced hydrocarbon gases display normal isotope sequences δ 13 C 1 <δ 13 C 2 <δ 13 C 3; no isotope reversal was observed under all experimental pressure conditions. For oil-prone Type-I kerogen: moderate water pressure (50–190 bar) increases δ 13 C 1 by accelerating oil cracking, while WP > 190 bar restrains secondary oil cracking and generates 12C-enriched methane, ethane, and propane. LP exerts dual controls: 125–625 bar LP gradually shifts the reactor toward a closed system and boosts oil cracking to form 13 Crich C 1 –C 2, whereas 625–2,000 bar LP suppresses oil cracking and lightens all gaseous δ 13 C values. For gas-prone Type-III kerogen, elevated WP facilitates primary kerogen cracking; progressive mixing of early-formed 13 C-enriched initial gas and late-stage 12 C-depleted cracking gas causes continuous depletion in 13 C 1. LP of 125–625 bar weakens hydrocarbon expulsion and hinders kerogen cracking, yielding heavier methane isotopes, while LP above 625 bar imposes negligible impacts on kerogen pyrolysis. Distinct pressure responses between the two kerogen types originate from their divergent hydrocarbon generation pathways (secondary oil cracking vs. primary kerogen breakdown). Our work demonstrates that pressure must be incorporated into natural gas maturity assessments using carbon isotope proxies, and confirms the favorable deep hydrocarbon resource potential of continental lacustrine source rocks in eastern China.
Julius Incillo Jimenez, Nitin Kumar Tripathi, Ashish Pandey, Sangam Shrestha, Kuo Chieh Chao
In previous years, water is abundant in the Padsan River Watershed, even in tropical climates. However, with increasing variability due to global warming, the watershed faces disruption of water resources. This requires thorough study, yet with fragmented data management, it becomes challenging. With technological advantages, integrated water resources management (IWRM) becomes possible using open-access data to understand the potential impact of climate variability. The corrected Climate Hazards Group InfraRed Precipitation (CHIRPS) and ten Coupled Model Intercomparison Project Phase 6 (CMIP6) becomes the notable open-access data including request-based institutional data were used as inputs for the Soil and Water Assessment Tools (SWAT) to quantify the impact of climate change on river discharge and groundwater recharge. Results showed that all Shared Socioeconomic Pathways (SSPs) will disrupt river discharge and groundwater recharge, with a prominent increase in river discharge. Furthermore, SSP 585 in the 2090s has a more notable impact on river discharge than others. In contrast, the SSP 126 has a lesser impact but displays higher variability across the rest of the century. This important simulated observation highly supports the Philippine Development Plan (PDP) aims, which is that climate change's impact could disrupt existing infrastructure and recharge conservation while establishing recharge areas to combat water scarcity during the dry period in the watershed. In contrast to the PDP regarding groundwater use, the study also supports the increasing conjunctive use of surface and subsurface resources, given that comprehensive management of the subsurface extraction must be established based on the study’s results.
Sedimentation in hydropower reservoirs is a major challenge for sustainable energy production. It reduces storage capacity, increases turbine abrasion, and raises operational costs, while also causing environmental impacts and operational management difficulties. Therefore, the identification of appropriate sediment management strategies is essential for maintaining reservoir sustainability and operational performance. However, many reservoirs have limited hydrological and sediment monitoring data, which restricts the application of conventional process-based methods. This study proposes a multi-criteria decision-making framework that integrates the Best-Worst Method (BWM) and the Combined Compromise for Ideal Solution (CoCoFISo) method to prioritize sediment management strategies under data-scarce conditions. Ten management strategies were evaluated using four dimensions: economic, environmental, technical, and social. Criterion weights were determined using BWM, an optimization-based method for deriving weights from expert judgments. The CoCoFISo method was used to rank the strategies by combining additive and multiplicative aggregation mechanisms to handle complex decision problems. The results show that the technical dimension received the highest weight (0.365), while the social dimension received the lowest weight (0.089). At the criterion level, sediment control effectiveness (C7), impact on hydropower generation (C6), and sediment connectivity (C3) received the highest global weights of 0.212, 0.151, and 0.147, respectively. Reforestation (S1) achieved the highest score and ranked first, followed by vegetative filter strips (S2) and check dams (S4). Several middle-ranked strategies had closely spaced final scores, resulting in small differences in their relative positions. Sensitivity and comparative analyses were conducted to assess the stability of the resulting rankings. The proposed BWM-CoCoFISo framework provides a structured decision-support approach for prioritizing sediment management strategies when monitoring data are limited.
