Steep Topography Research Articles

Landslide Hazard and Rainfall Threshold Assessment: Incorporating Shallow and Deep-Seated Failure Mechanisms with Physics-Based Models

Landslides pose a significant threat worldwide, leading to numerous fatalities and severe economic losses. The city of Manizales, located in the Colombian Andes, is particularly vulnerable due to its steep topography and permeable volcanic ash-derived soils. This study aims to assess landslide hazards in Manizales by integrating shallow planar and deep-seated circular failure mechanisms using physics-based models (TRIGRS and Scoops3D). By combining hazard zonation maps with rainfall thresholds calibrated through historical data, we provide a refined approach for early warning systems (EWS) in the region. Our results underscore the significance of the landslide hazard maps, which combine shallow planar and deep-seated circular failure scenarios. By categorizing urban areas into high, medium, and low-risk zones, we offer a practical framework for urban planning. Moreover, we developed physics-based rainfall thresholds for early landslide warning, simplifying their application while aiming to enhance regional predictive accuracy. This comprehensive approach equips local authorities with essential tools to mitigate landslide risks, refine hazard zoning, and strengthen early warning systems, promoting safer urban development in the Andean region and beyond, as the physics-based methods used are well-established and implemented globally.

Scenario‐Based Volcano Slope Stability Hazard Analysis: Case Study of Augustine Volcano, Alaska

AbstractVolcanoes worldwide have undergone cyclic destruction of their edifices, generating catastrophic volcanic debris avalanches. Augustine Volcano in Alaska, USA, has a history of debris avalanches, causing cyclic destruction of the edifice and cascading hazards. These collapses, together with eruption‐related changes in the edifice structure, change the slope stability hazard of the volcano over time. This study aims to develop a current view of the slope stability hazard at Augustine Volcano by (a) characterizing collapse‐prone source areas on the edifice under various scenarios typical of dynamic volcanic environments and (b) identifying the controlling factors that underlie the slope stability hazard. Scenario‐based slope stability assessment was conducted using a quasi‐3D limit equilibrium method to test for the effect of various factors that drive or resist failure, including topography, shallow edifice structure, strength of edifice‐forming materials, pore fluid pressure distribution, and local and regional seismicity. Results show that in all scenarios assessed, the slopes of Augustine Volcano are stable with a factor of safety (FOS) greater than 1. The FOS, however, decreases with decreasing strength of edifice‐forming materials, pore fluid pressurization, and earthquake loading. The location of the relatively less stable slope, changes to the southwestern flank when accounting for subsurface heterogeneities derived from geophysical observations. Subsurface heterogeneity is thus a key underlying factor, along with steep topography, in controlling where collapse‐prone source areas occur, and it should be accounted for in volcanic slope stability hazard assessments.

Causality analysis and prediction of soil saturated hydraulic conductivity by combining empirical modeling and machine learning techniques

Soil saturated hydraulic conductivity (Ks), as a fundamental property governing the behavior of water in the soil environment, is important to agriculture, environmental quality, water resources management, and engineering practices. However, the intricate interplay between Ks and environmental factors leads to substantial variability, making direct measurement costly and challenging. To provide a cost-effective indirect method with regard to Ks estimation, we proposed a portable modeling framework combing partial least squares structural equation modeling and artificial neural network (PLS-SEM-ANN). The framework was applied to a mountainous watershed characterized by humid climate, steep topography, and diverse land use. This approach demonstrated that the PLS-SEM-ANN was efficient in Ks modeling with a prediction accuracy of more than 80 % (R2 of 0.989 and 0.862 for model training and validation), which is comparable to that of the conventional artificial neural network (R2 of 0.993 and 0.843 for model training and validation). According to structural equation modeling, land use significantly affected Ks through direct (β = 0.237, p < 0.05) and indirect (β = 0.263, p < 0.05) ways, and soil properties, especially soil particle composition, were the most direct factor affecting Ks (β = 0.410, p < 0.01), while topography had a lesser effect on Ks (β = -0.023, p > 0.05). However, Shapley additive explanations (SHAP) analyses of PLS-SEM-ANN revealed significant nonlinear effects of topography on Ks, especially slope (SHAP mean absolute value = 0.92). Moreover, threshold testing showed that there was an abrupt change in the slope-Ks relationship at approximately 21°, with the effect of slope on Ks turning from positive to negative. This study provides an approach with explainable and transparent modeling results for Ks.

Abyssal Slope Currents

Abstract Realistic computational simulations in different oceanic basins reveal prevalent prograde mean flows (in the direction of topographic Rossby wave propagation along isobaths; a.k.a. topostrophy) on topographic slopes in the deep ocean, consistent with the barotropic theory of eddy-driven mean flows. Attention is focused on the Western Mediterranean Sea with strong currents and steep topography. These prograde mean currents induce an opposing bottom drag stress and thus a turbulent boundary-layer mean flow in the downhill direction, evidenced by a near-bottom negative mean vertical velocity. The slope-normal profile of diapycnal buoyancy mixing results in down-slope mean advection near the bottom (a tendency to locally increase the mean buoyancy) and up-slope buoyancy mixing (a tendency to decrease buoyancy) with associated buoyancy fluxes across the mean isopycnal surfaces (diapycnal downwelling). In the upper part of the boundary layer and nearby interior, the diapycnal turbulent buoyancy flux divergence reverses sign (diapycnal upwelling), with upward Eulerian mean buoyancy advection across isopycnal surfaces. These near-slope tendencies abate with further distance from the boundary. An along-isobath mean momentum balance shows an advective acceleration and a bottom-drag retardation of the prograde flow. The eddy buoyancy advection is significant near the slope, and the associated eddy potential energy conversion is negative, consistent with mean vertical shear flow generation for the eddies. This cross-isobath flow structure differs from previous proposals, and a new one-dimensional model is constructed for a topostrophic, stratified, slope bottom boundary layer. The broader issue of the return pathways of the global thermohaline circulation remains open, but the abyssal slope region is likely to play a dominant role.

Conceptual modelling on water-rock reaction and genesis of high pH fluids in a typical granitoid geothermal reservoir: A case from Indus-Tsangpo Suture Zone, India

Two novel thermal springs are investigated along ITSZ of north-west Himalayas in Demchok geothermal belt. The area consists of deep-seated faults in LGB; despite being situated in ITSZ, fluid chemistry of these low-temperature springs differs significantly, specifically in terms of low TDS (161–168 mg/l) and high alkalinity, with neighbouring springs in Puga and Chumathang (∼2100 mg/l). Thermal waters are mixed type (Na–Cl–HCO3–SO4) with elemental composition influenced through silicate rock weathering and partial carbonate dissolution. Variable temperature speciation (25 °C–200 °C) indicates that in reservoir fluid, Na+ precedes over other cations, while sulfate and carbonate complexes being prominent for Mg and Ca, respectively. Aquifer boiling modelling suggests calcite scaling and silica mineral equilibration in reservoir. Environmental stable isotopes (δ18O and δD) suggest high-altitude recharge from Jamlung La (6156 m), with altitude-effect of 0.43 ‰ isotopic depletion per 100 m elevation in altitude. As only silica minerals equilibrate with thermal waters, silica, and gas geothermometers give most conservative estimate of reservoir temperature (125°−135 °C). The steep topography enables extensive lateral flow of hot fluids in outflow zone, leading to high mixing and a high water-rock ratio, which contribute to lower TDS. Conceptual modelling reveals that geothermal system is a low-enthalpic hydrothermal system controlled by joints and permeable fractures, having deep fluid circulation of meteoric waters of ∼1275 m at sub-surface, with anomalous geothermal gradient and steam migration as reservoir heat sources. These fluids closely resemble springs of Guerrero state, Mexico, exhibiting similarities in low-TDS, high-pH, and high concentration of dissolved silica.

Impact of Steep Seabed Terrains on Oscillating Buoy-Wave Energy-Converter Performance

This paper employs Computational Fluid Dynamics (CFD) methods to develop a numerical model of an oscillating buoy-wave energy converter and investigates the impact of steep seabed topography near islands and reefs on its performance. The model’s accuracy is validated by comparison with experimental results from the published literature. Subsequently, the influence of deployment location, reef-front slope gradient, and reef-flat water depth on the device’s performance is analyzed. The results indicate that the strategic utilization of steep seabed topography can significantly enhance the energy capture efficiency of the device in long-wave regions. This study provides valuable references for the design and deployment of oscillating buoy-wave energy converters in near-reef areas.

Near real-time spatial prediction of earthquake-triggered landslides based on global inventories from 2008 to 2022

Near real-time prediction of earthquake-triggered landslides can rapidly forecast the spatial distribution of coseismic landslides just after a great earthquake, and provide effective support for emergency response. However, the prediction of earthquake-triggered landslides has always been a great challenge because of low accuracy and high false alarms. This work proposes a novel fuzzy deep learning (FuDL) model for near real-time earthquake-triggered landslide spatial prediction. Fuzzy learning theory is for the first time employed in earthquake-triggered landslide prediction. The FuDL has high generalization and robustness, effectively improving the accuracy of earthquake-triggered landslide prediction. Eighteen earthquake-triggered landslide inventories worldwide from 2008 to 2022 are employed to conduct ETL prediction. According to the chronological order, 15 earthquake-triggered landslides from 2008 to 2018 are adopted to train the FuDL model, and 3 earthquake-triggered landslides from 2019 to 2022 are utilized for near real-time earthquake-triggered landslide prediction. Furthermore, this work reveals that ground movement, relatively steep and high topography, and strong seismic intensity are critical factors affecting the spatial distribution of earthquake-triggered landslides. In addition, this work conducted a detailed analysis of the distribution patterns of earthquake-triggered landslides on a global scale.

Intrusions and Turbulent Mixing above a Small Eastern Mediterranean Seafloor Slope

Abstract Growing evidence is found in observations and numerical modeling of the importance of steep seafloor topography for turbulent diapycnal mixing leading to redistribution of suspended matter and nutrients, especially in waters with abundant internal tides. One of the remaining questions is the extent of turbulent mixing away from and above nearly flat topography, which is addressed in this paper. Evaluated are observations from an opportunistic, weeklong mooring of high-resolution temperature sensors above a small seafloor slope in about 1200-m water depth of the eastern Mediterranean. The environment has weak tides, so that near-inertial motions and near-inertial shear dominate internal waves. Vertical displacement shapes suggest instabilities to represent locally generated turbulent overturns, rather than partial salinity-compensated intrusions dispersed isopycnally from turbulence near the slope. This conclusion is supported by the duration of instabilities, as all individual overturns last shorter than the mean buoyancy period and sequences of overturns last shorter than the local inertial period. The displacement shapes are more erratic than observed in stronger stratified waters in which shear drives turbulence and better correspond with predominantly buoyancy-driven convection turbulence. This convection turbulence is confirmed from spectral information, generally occurring dominant close to the seafloor and only in weakly stratified layers well above it. Mean turbulence values are 10–100 times smaller than those found above steep ocean topography, but 10 times larger than those found in the open-ocean interior.

Participatory Assessment of Agriculture Land and Vegetation Associated Issues and Possible Interventions in Gurage Zone, Ethiopia

Land degradation and depletion of natural forests made agriculture unsustainable and threaten communities and ecosystems as a whole. The objective of this participatory assessment was to identify researchable issues related to agricultural land and vegetation cover in Gurage zone. Accordingly, seven representative districts were selected and from each district two representative kebeles were purposively selected. Focus Group Discussion with farmers, development agents and subject matter specialists and direct observation were important primary sources of information. The survey result depicts in the Gurage zone land degradation, undulating steep slope topography, small and overwhelmed land tenure, inappropriate land use system, cultural landscape mismanagement, deforestation of indigenous trees and expansion of eucalyptus tree, and decreasing enset production are the major identified problems associated with land use and vegetation cover of the study area. In the mixed farming system, enset is produced as a homestead farm and its coverage is decreasing due to disease, lack of processing machines, and shortage of organic matter. Due to the expansion of eucalyptus and land use change, the majority of native trees are disappearing or decreasing in area coverage. Therefore, enset and eucalyptus require suitable policy attention. In the mountainous areas of Gurage; limited land availability, soil degradation, shortage of appropriate farm technologies, water scarcity, lack of knowledge for alpine agriculture and inconvenient topography for mechanized farming machines issues threaten agriculture of area. Despite the fact that there are few attempts to control land degradation; the issue still needs much attention. Appropriate agricultural technologies and knowledge suited for mountain agriculture, dense populations, enset-based farming systems, and small land tenure are important priority research focus areas for future research.

Quantifying Earth's Topography: Steeper and Larger Than Projected in Digital Terrain Models

AbstractGrid‐ or pixel‐based models, used across various scientific disciplines from microscopic to planetary scales, contain an unquantified error that bias our interpretation of the data. The error is produced by projecting 3D data onto a 2D grid. For Digital Terrain Models (DTMs) the projection error affects all slope‐dependent topographic metrics, like surface area or slope angle. Due to the proportionality of the error to the cosine of the slope, we can correct for it. We quantify the error and test the correction using synthetic landscapes for which we have analytical solutions of their metrics. Application to real‐world landscapes in California, reveal the systematic underestimation of surface area by up to a third, and mean slope angles by up to 10° in steep topography in current DTMs. Correcting projection errors allow for true estimates of surface areas and slope distributions enabling physics‐based models of surface processes at any spatial scale.

Upland vegetation removal as a potential tool for facilitating landward salt marsh migration

To increase the resilience of salt marshes subject to sea‐level rise impacts, managers can focus on interventions within current marsh footprints or in adjacent uplands to facilitate landward marsh migration. The latter approach may be more appropriate when degradation is severe and in situ intervention options are limited. Strategies for facilitating marsh migration include removing artificial barriers, soil grading to reduce steep topography, and manipulating adjacent upland vegetation that can hinder migration, but experiments testing the effectiveness of these activities are limited. We therefore conducted a field experiment to determine if physically removing three upland vegetation types (forest, shrub, and Phragmites australis) adjacent to a Rhode Island salt marsh facilitates short‐term marsh migration. Upland vegetation removal led to increased ambient light in all habitats, significantly enhanced marsh plant cover, extent, and elevation in shrub habitat, and declines in total bird abundance in forest and shrub habitats. Enhanced migration did not occur in forest or Phragmites habitats, and in shrubs, marsh plants only colonized where Baccharis halimifolia, common in upper marsh borders, had been removed. Five years after removal, all upland habitats and associated vegetation were indistinguishable from initial conditions. Our study suggests that upland plant removal might provide a limited window for facilitating salt marsh migration and that more intensive methods may be needed for sustained, longer‐term benefits. It also demonstrates that there may be ecological trade‐offs to consider when altering upland habitats to enhance landward marsh migration.

Rainfall-induced Landslide in the Lesser Himalaya: A Case Study of the Pallotari Landslide, Lamjung, Central-West Nepal

The Pallotari area, located in the Marsyangdi Rural Municipality, Lamjung, central-west Nepal, within the Lesser Himalaya, was impacted by a series of rainfall-induced landslides in July 2020. This study focuses on the Pallotari landslide, one of the major landslides in the area. Geological and engineering geological studies were performed to identify the causes of this landslide, and its impacts to the local community. Our results indicate the major causative factors to be intensive rainfall, steep topography with loose colluvial soil, and some anthropogenic activities such as the construction of the rural roads through the crown area. The study area still has hanging colluvial material on the crown as well as on the left flank of the landslide, and the numerical model for slope stability analysis indicates it to be unstable even in the unsaturated condition. The colluvial material in the middle portion of the landslide also has the risk of failure in the saturation condition which can be due to intensive rainfall. However, the rock slope stability analysis using the kinematic analysis does not show any contribution to the orientation of discontinuities on the slope failure. The presence of several transverse and longitudinal cracks in the surrounding of the landslide are signs of future failure.

Internal Tides at the Coast: Energy Flux of Baroclinic Tides Propagating into the Deep Ocean in the Presence of Supercritical Shelf Topography

Abstract The generation of internal tides at coastal margins is an important mechanism for the loss of energy from the barotropic tide. Although some previous studies attempted to quantify energy loss from the barotropic tides into the deep ocean, global estimates are complicated by the coastal geometry and spatially and temporally variable stratification. Here, we explore the effects of supercritical, finite amplitude bottom topography, which is difficult to solve analytically. We conduct a suite of 2D linear numerical simulations of the barotropic tide interacting with a uniform alongshore coastal shelf, representing the tidal forcing by a body force derived from the vertical displacement of the isopycnals by the gravest coastal trapped wave (of which a Kelvin wave is a close approximation). We explore the effects of latitude, topographic parameters, and nonuniform stratification on the baroclinic tidal energy flux propagating into the deep ocean away from the shelf. By varying the pycnocline depth and thickness, we extend previous studies of shallow and infinitesimally thin pycnoclines to include deep permanent pycnoclines. We find that scaling laws previously derived in terms of continental shelf width and depth for shallow and thin pycnoclines generally hold for the deeper and thicker pycnoclines considered in this study. We also find that baroclinic tidal energy flux is more sensitive to topographic than stratification parameters. Interestingly, we find that the slope of the shelf itself is an important parameter but not the width of the continental slope in the case of these steep topographies. Significance Statement The objective of this study is to better understand how vertical density stratification, which can vary seasonally in the ocean, affects the interaction of tides with steep coastal topography and the generation of waves that travel away from the coast in the ocean interior. These waves in the interior can travel over long distances, carrying energy offshore into the deep ocean. Our results suggest that the amount of energy in these internal waves is more sensitive to changes in topography and latitude than to the vertical density profile. The scaling laws found in this study suggest which parameters are important for calculating global estimates of the energy lost from the tide to the ocean interior at the coastal margins.

Impacts of Moisture Advection Scheme on Precipitation in the Steep Topography Region between the Tibetan Plateau and the Sichuan Basin

Abstract Water vapor transport is a crucial process in modeling and can contribute to errors in precipitation forecasts. To investigate the sensitivity of precipitation to the moisture advection scheme, this study introduced the two-step shape-preserving advection scheme (TSPAS), which has been proven to improve precipitation simulation over steep topography at lower resolutions, into the Southwest Center Weather Research and Forecast (WRF)-based Intelligent Numerical Grid Forecast System (SWC-WINGS) at a convection-permitting resolution. According to experiments conducted throughout the summer of 2021, the precipitation over the eastern slope of the Tibetan Plateau (TP) is highly sensitive to the moisture advection scheme. TSPAS successfully improved precipitation over the eastern slope of the TP, especially for torrential rainfall. The fractions skill score (FSS) is improved by 0.075 (27.78%) for daily precipitation with a threshold of 100 mm. Compared with the experiment with the original WRF advection scheme, the TSPAS reduced the overestimation of precipitation in the topographic region and excessive water vapor transport in a low-level atmosphere. To understand the precipitation improvement contributed by the advection scheme, additional experiments were conducted for a particular precipitation process from two approaches: switching advection schemes during the rainfall evolution and updating the variables related to moisture advection individually. Results demonstrate that the precipitation improvement is mainly contributed by the moisture advection scheme before the precipitation. Among the different variables, the combination of wind and water vapor was the most influential factor causing the precipitation improvement under the TSPAS.

The Vertical Tilt of Mesoscale Eddy in the Northern South China Sea in a High‐Resolution Numerical Simulation

AbstractUsing a high‐resolution numerical model, we investigate the influence of slope topography on the vertical tilted structure of mesoscale eddies in the northern South China Sea (NSCS). The model effectively captures key features including trajectories, intensities, and three‐dimensional tilted structures of these eddies. By compositing all NSCS eddies on the slope and in the basin, a more pronounced southwestward tilt in slope eddies is found from the sea surface down to the deep, compared to basin eddies. The tilt distance of slope eddies is approximately 1.8 times that of basin eddies, with the strongest eddy tilt near the Dongsha Islands. Variations in topography gradient induce noticeable changes in both the magnitude and direction of the eddy tilt. Due to potential vorticity conservation, the eddies' lower part follows isobaths, while the upper part drifts southwestward. This rapidly increases a southward eddy tilt during the upslope phase (USP) and a gradual transition to a southwestward tilt in the downslope phase (DSP). Moreover, the lower eddy part responds more significantly and earlier (about 20 days) to topography than the upper eddy part, moving faster and tilt‐developing more rapidly. The lower eddy part tilts larger during the USP, roughly 2.5 times than that of the upper eddy part. In the subsequent DSP, the tilt of lower eddy part decreases, about half of that in the upper eddy part. This study reveals the complex interactions between mesoscale eddies and steep slope topography, aiding further understanding the dynamics of eddy tilt and propagation.

Severity of topsoil compaction controls the impact of skid trails on soil ecological processes

Abstract Skid trails are a major management‐induced disturbance in temperate forest ecosystems with considerable impact on soil ecological processes that are so far poorly understood. In German forests, skid trails comprise 10%–20% of the forest area that is potentially affected by soil compaction through heavy machinery. We systematically investigated the influence of skid trails on physical, chemical and microbiological soil parameters at 84 paired plots across four Central European forest types. In low mountain forests with steeper topography, skid trails had more drastic effects than in lowland forests. Skid trails in low mountain areas showed a decrease in the C to N ratio of microbial biomass (MBC/MBN), as well as increased microbial (MBC/SOC) and enzyme activities leading to faster carbon turnover (lower C/N, EOC/EN) and increased CO2 losses (CO2/SOC) from the soil. The overall effects of the skid trails in lowland forests were small. On base‐poor soils, we found an increase in the MBC/MBN ratio, while skid trails in base‐rich lowland soils showed a reduction in CO2/SOC, suggesting a proportional increase in soil carbon storage. Regardless of region‐specific effects, the relative increase in the bulk density of the fine soil was identified as a ‘golden trait’ that determined the effects of skid trails on many soil parameters, as shown by negative correlations with SOC, N, MBC, MBN, MBP, MBC/SOC and CO2/SOC and positive ones with the activities of certain hydrolytic enzymes. Synthesis and applications: Our data clearly showed that carbon conversion processes and soil respiration leading to significant carbon and nutrient losses increased significantly on skid trails in low mountain regions with relatively steep slopes, which was in sharp contrast to lowland sites. The strong context dependence of our findings suggests that the mapping of soil conditions in terms of slope, substrate and moisture with high spatial resolution is mandatory to assess the vulnerability of sites to soil compaction by heavy machinery. Based on such vulnerability analysis, negative impacts can be minimised through the designation of permanently fixed skid trails, technical adaptation of vehicles (e.g. wide base tyres) as well as careful planning and timing of management operations that should be restricted to dry weather and soil moisture conditions or periods of frost.

Internal waves generated from asymmetric topographies

Previous experimental and theoretical research on tidally generated internal waves over oceanic topography has often used symmetric topographic profiles. However, due to the complex nature of real ocean topography, the effect of asymmetry cannot be overlooked. Studies have shown that topographic complexities, including asymmetry, can have a significant impact on internal wave generation, but topographic asymmetry has not yet been explored in a systematic manner. This work presents a comparison of tidally generated internal waves from nine different two-dimensional asymmetric topographies, consisting of a steeper Gaussian curve on one side, and a wider Gaussian curve on the other. The amplitude of the wider curve varies from 60% of the steeper curve to its equivalent. Two oscillation frequencies are tested. Kinetic energy density in tidally generated internal waves on each side of the topography is compared qualitatively and quantitatively, in both physical and Fourier space. When compared to similar symmetric topographies, waves generated by the asymmetric topographies varied distinctly in both magnitude and wavenumber distribution of kinetic energy density. Waves on the relatively steep side of the topography contain up to 50% more kinetic energy than on the wider side. However, there is very little kinetic energy at the higher wavenumbers associated with the steeper topography. Instead, the internal wavefield is dominated by lower wavenumbers, 50%–90% of the kinetic energy density is contained in wavelengths corresponding to the wider side of the topography. Decreasing the amplitude of the wider curve does not make an appreciable difference in the kinetic energy density spectrum. Thus, the differences quantified here are due solely to changing slope and show the effect which relatively slight asymmetry has on internal wave generation.

Responses of soil moisture at different topographic positions to rainfall events along a steep subtropical forested hillslope

AbstractUnderstanding the dynamic response of soil moisture to rainfall is crucial for describing hydrological processes at the hillslope scale. However, because of sparse monitoring coupled with the complexity of water movement and steep topography, the findings of rainfall‐related soil moisture dynamics have not always been consistent, indicating a need for systematic investigations of soil moisture dynamics and infiltration patterns following rainfall inputs at multiple topographic positions along a hillslope. This study aimed to examine the nature of these responses by characterizing and quantifying the response amplitude, rate and time for 37 large rainfall events at 25 combinations of topographic positions and soil depths along a steep forested hillslope. Our results showed that soil moisture responses under different rainfall patterns could be attributed to one or the other rainfall characteristics, such as rainfall intensity and amount. However, soil moisture dynamics at different hillslope positions after rainfall varied widely due to the controls of soil properties, topography, and non‐equilibrium flow. Preferential flow was more evident under dry initial soil conditions than under wet initial soil conditions. Findings of this study reveal that the dynamic response patterns of soil moisture to rainfall do not always follow topographic controls, which can improve our understanding of water cycling related to the infiltration process at the hillslope scale, and support water resources management in subtropical mountain ecosystems.

The seasonal evolution of the Yellow Sea Cold Water Mass Circulation: Roles of fronts, thermoclines, and tidal rectification

The Yellow Sea Cold Water Mass (YSCWM), surrounded by thermocline and fronts, is one of the most notable hydrological characteristics of the Yellow Sea (YS) in the summer. Temperature structure at the boundary of the YSCWM drives the Yellow Sea Cold Water Mass Circulation (YSCWMC). However, the 3D structure of YSCWMC remains unclear. The position, seasonal evolution, and dynamical mechanisms of the YSCWMC were examined by observations and high-resolution numerical model. It was found that the core of the YSCWMC is located at the junction of the fronts and the thermocline during the summer. Furthermore, the YSCWMC exhibits remarkable seasonal variations characterized by a progressive shrinking and deepening dependence on the position and strength of the fronts and thermocline. The YSCWMC is geostrophic at the basin scale, with the barotropic pressure term determining the direction of the circulation and the baroclinic pressure term controlling the vertical structure of the circulation. Fronts yield a baroclinic effect in the thermal field and affect the sea surface elevation in the barotropic process. Therefore, fronts are crucial to the formation of the YSCWMC. Nevertheless, under conditions of steep topography, tidal rectification is comparable to the frontal contribution to the circulation.

Characterization of Southern Peru Hydrothermal Systems: New Perspectives for Geothermal Exploration Along the Andean Forearc

AbstractThis study provides a comprehensive characterization of various hydrothermal systems in Southern Peru ranging from the faulted Precordillera's steep topography up to the volcanic High Cordillera (&gt;4,000 m asl). The objective is to investigate thermal anomalies that may potentially serve as new geothermal resources. Our integrated approach combines: (a) geochemistry from 14 hot springs sampled throughout the Tacna region, and (b) 3D numerical modeling of coupled groundwater and heat transfer considering topography and faults embedded in homogeneous permeability. Water and gas analysis indicates that the springs located near volcanoes discharge Na‐K‐Cl waters with high temperatures (&gt;87°C), high Total Dissolved Solid concentrations (TDS &gt;3,452 mg/L), and free gases dominated by CO2 (&gt;90 vol%). Springs located along the regional faults in the Precordillera discharge Ca‐SO4 and Na‐K‐Cl waters with moderate temperatures (27–53°C), intermediate TDS concentrations (464–2,458 mg/L), radiocarbon ages between 1.4 and 7.9 kyr, and free gases dominated by N2 (&gt;95 vol%). The Aruma springs, which are located at the transition between the High and the Precordillera, display intermediate characteristics. Numerical models accurately replicate the locations and temperatures of the fault‐related springs only for permeable faults (&gt;10−14 m2), revealing the creation of 100‐km long thermal plumes along faults, locally rising up the 150°C‐isotherm to about ∼1,000 m below the surface. This approach clearly distinguishes the spring origins, which are volcanic in High Cordillera and tectonic in Precordillera. Moreover, we highlight that steep topographic gradient and permeable reverse faults in the Andean forearc may generate considerable thermal anomalies, opening perspectives for the geothermal exploration.