Search Results (716)

Soil erosion affects agricultural and environmental sustainability and needs to be addressed. The Cagayan de Oro River Basin (CDORB), one of the major river basins in the Philippines, provides economic, social, and environmental services to the city and municipalities inside the basin. More than 70% of the area of the river basin is devoted to various forms of agricultural production. Land cover critically influences erosion dynamics as vegetation reduces rainfall impact, enhances infiltration, and limits sediment transport. This study employs the Hydrologic Engineering Center–Hydrologic Modeling System (HEC-HMS) integrated with the Modified Universal Soil Loss Equation (MUSLE) to evaluate soil erosion under different rainfall return periods (5, 10, 25, 50, 100 years) and four land cover scenarios: No Reforestation Intervention (NI), Maximum Forest Cover (MF), Slope-Based Land Use (SB), and Reforestation on Public Domain (PD). Model results showed that soil loss increased with rainfall intensity, with NI yielding the highest average erosion of 1443 t ha⁻¹. Conservation scenarios reduced erosion by up to 53% compared to NI. Among the conservation scenarios, MF, SB, and PD yielded average erosion of 21, 716, and 1304 t ha⁻¹, respectively. While the MF scenario had the least soil loss, no space was assigned for economic production. On the other hand, the SB approach offered the best balance, halving erosion across all rainfall return periods, but at the same time has sufficient space available for economic production. These findings demonstrate the scientific value of integrating HEC-HMS and MUSLE for event-based erosion modeling and highlight how comparing multiple land-cover scenarios can inform data-driven land use planning and policy formulation for sustainable watershed management. Full article

Rainfall retention and runoff detention are the key hydrological processes that reduce runoff from green roofs. This study aims to quantify and model the hydrological response of nine combinations of growing substrates and drainage layers for extensive green roofs. Retention and detention capacities were evaluated using laboratory column experiments under two extreme initial moisture conditions—air-dried (D) and field capacity (W)—and three rainfall intensities (30, 60, and 100 mm h⁻¹). Regardless of the substrate–drainage combination, retention capacity, W_R, was significantly higher under dry conditions than under wet ones. Under wet conditions and rainfall intensity of 30 mm h⁻¹ (30 W tests), the mean W_R value (5.2 mm) was significantly lower than those recorded at higher intensities (14.3 and 14.2 mm, for 60 W and 100 W tests, respectively). Detention capacity, W_D, was less influenced by initial moisture and rainfall intensity, with mean values ranging from 7.4 to 10.9 mm. The distinct hydrological responses of green roof columns in the two antecedent moisture conditions were attributed to contrasting infiltration mechanisms: capillary flow dominated under dry conditions, while gravity-driven preferential flow prevailed under wet conditions. The application of a simple reservoir-routing model revealed that the AgriTerram (AT)—expanded perlite (EP) combination achieved the greatest reduction in total outflow volume and peak runoff. Under wet initial conditions, no single configuration clearly outperformed the others. This study highlights how the combined use of simulated rainfall experiments and a reservoir-routing model enables the identification of the most effective combination of substrate and drainage system to improve the hydrological performance of green roofs. Full article

Gully erosion is a major driver of land degradation globally, particularly in semi-arid regions where it is fundamentally controlled by rainfall and runoff dynamics. Understanding how rainfall translates into runoff in gullied landscapes is crucial for predicting erosion processes and modelling runoff to inform land management strategies. In this study, rainfall-runoff analysis was conducted using high-resolution rainfall and runoff data from intensely monitored alluvial gullies in the semi-arid regions of northern Australia. Runoff responses were strongly seasonal, with flashy but low-volume flows during the early wet season (October–November) and prolonged, high-discharge events during peak rainfall months (December–March). Antecedent soil moisture had a limited influence on runoff generation, likely due to rapid wetting–drying cycles and shallow infiltration depths. Notably, rainfall-runoff behavior diverged with catchment-to-gully area ratio (A_ca): linear runoff to rainfall responses were observed where gullies were eroded to the catchment limit (A_ca ≈ 1) whereas high-A_ca systems (A_ca > 5) exhibited threshold, stepwise behavior with upslope contributions activating at ~26 mm event rainfall. Field infiltration tests showed upslope catchment infiltration capacity was ~70% higher than on gully floors (~36 vs. 21 mm h⁻¹). This indicates greater near-surface storage and delayed upslope runoff, consistent with an activation threshold for upslope contributions. Mean rainfall–runoff ratios were higher in low-A_ca gullies (≈0.52–0.68) than in high-A_ca systems (≈0.40–0.46). These findings have implications for rainfall-runoff modelling, process-based understanding of gully erosion and gully management in semi-arid environments. Full article

Subalpine meadow soil is widespread in the steep valleys of the eastern Tibetan Plateau. Owing to its unique structure and climatic conditions, rainfall can trigger extensive ecohydrological disaster, characterized by soil disintegration and shallow landsliding. This phenomenon leads to significant soil erosion and degradation of meadow ecosystems, highlighting the ecological vulnerability of the region. Field investigations have identified porewater pressure from infiltrated rainwater and gravitational pressure on saturated meadow soil as the primary drivers of the landsliding. Building on this understanding, efforts were made to assess the risk of subalpine meadow soil erosion induced by extreme rainfall near Xinduqiao County using the TRIGRS model and the coupled TRIGRS-TOPMODEL (TOP-TRIGRS). Validation of the simulated results against observed erosion events revealed that TOP-TRIGRS tends to predict unstable areas more accurately, particularly in the lower to mid-sections of slopes with gentler gradients, in line with theoretical models of shallow landslide. Specifically, while TRIGRS identified 50.31% of actual shallow landslides, TOP-TRIGRS reached 80.35%. Moreover, the AUC values for TRIGRS and TOP-TRIGRS were 0.787 and 0.896, respectively, indicating the superior predictive performance of TOP-TRIGRS. Accurate prediction of shallow landslides in subalpine meadow soil is vital for informing ecological management regulations and advancing soil and water conservation efforts in the eastern Tibetan Plateau. Full article

Heavy rainfall infiltration is a key disaster-inducing factor that triggers the softening of surrounding rock and deformation of support structures in tuff gully tunnels. Based on the gully section of the left line of the Dabao Tunnel of the Leigongshan–Rongjiang Expressway in Guizhou Province, this study systematically reveals the synergistic disaster-inducing mechanism of “topography-seepage-softening” in tuff gully tunnels under heavy rainfall infiltration through laboratory tests and FLAC3D 3D numerical simulations. The main innovative conclusions are as follows: (1) The “phased” attenuation law of tuff mechanical parameters was quantified, and the critical water content for significant strength deterioration was determined to be 2.5%, with a saturated softening coefficient of 0.59. These results provide key data for early warning and evaluation of similar projects. (2) A “convergence-disorder” distribution pattern of pore water pressure controlled by gully topography was revealed. It was found that the rock mass directly below the aqueduct exhibits a disordered zone with downward-extending pore water pressure due to fluid convergence, with the maximum pore water pressure reaching 0.55 MPa. This clarifies the essence that tunnel stability is controlled by the coupling of topography and seepage field. (3) The key sensitive areas for tunnel stability—namely the gully bottom, arch haunches, and the area below the aqueduct—were accurately identified. The significant increase in displacement of these areas after rock stratum softening was quantified (e.g., the displacement at the crown of the secondary lining increased from 3 mm to 4 mm, and the influence range expanded to the arch haunches). This study clarifies the deformation characteristics and instability mechanism of tuff gully tunnels under heavy rainfall from two aspects: the “internal mechanism of rock mass softening” and the “external condition of topographic seepage control.” It can provide a theoretical basis and key technical pathway for disaster prevention and control as well as stability design of similar tunnels. Full article

The present research moves the focus from merely describing epikarst flow to quantifying its natural filtration performance and contaminant retention mechanisms through integrating in situ tracer experiments with controlled laboratory modelling—an approach seldom applied in previous studies. Two field experiments at Peč Cave demonstrated that the epikarst exhibits rapid hydraulic connectivity—evidenced by fast tracer breakthrough with virtual flow speeds between 0.0041 and 0.006 m/s—yet simultaneously provides strong attenuation, as shown by the low tracer recovery and near-complete removal of microbial contaminants as well as nitrogen compounds through retention, degradation, and dilution under natural infiltration conditions, including rainfall and snowmelt. Complementary laboratory simulations further confirmed this duality, with nitrate concentrations reduced by 30–50%. Field data and lab results consistently indicated that the epikarst does not merely transmit water but actively adsorbs and transforms pollutants. Overall, the epikarst on Suva Planina functions as an effective natural filtration layer that substantially improves groundwater quality before it reaches major karst springs, acting as a protective yet vulnerable “skin” of the aquifer. These findings highlight the epikarst’s critical role in Suva planina Mt. karst aquifer protection and results support consideration of epikarst in groundwater management strategies, particularly in regions where springs are used for public water supply. Full article

The rising urbanization and climate change have increased pluvial flood risks, especially in highly urbanized areas. This study focuses on the Lake Ganzirri area in Messina, Italy, where street-level floods have raised concerns for infrastructure resilience and public safety. This study aims to explore how to effectively represent key urban features, emphasizing buildings and low-impact development/sustainable urban drainage systems (LID/SUDS). For the buildings, a combination of referred approaches to represent buildings is compared against the widely used method to represent buildings as voids in a 2D mesh, ignoring them in the water balance calculations. For the LID/SUDS control elements, a 2D representation is presented and compared against the widely used 1D approach to model such elements. The study uses three well-known software packages—EPA-SWMM 5.2, HEC-RAS 6.2, and InfoWorks ICM 2021.9—applied to the Lake Ganzirri area, to explore the representation of buildings using the building void method (available in InfoWorks ICM 2021.9) against the proposed method (in HEC-RAS 6.2) to replicate runoff flow over a 2D model of a highly urbanized area. From scenario S0, three more scenarios were derived: S1 (S0 with pluvial drainage network), S2 (S1 with LID/SUDS control elements), and S3 (S0 with 2D representation of LID/SUDS), which were then compared against using four comparison schemes. Results show that the proposed method for representing buildings computed the propagation of the runoff comparable to when the building void method is used, with some shortcomings regarding mesh adjustments and computational times. Regarding the 2D representation of LID/SUDS, the effects were unperceivable on water depth maps (reduction in water depths of 1.5 mm on average for all the rainfall events). Still, they were reflected in the increase of 62% of the infiltration volume on average of all the rainfall scenarios and a decrease of 9.1% of water flowing outside the 2D area, therefore replicating the effect of capturing water. Full article

Soil aggregate stability plays a central role in mediating slope erosion, a key ecological process in North China. This study aimed to investigate how aggregate structures (reflected by rainfall intensity and vegetation-type differences) influence the erosion process. Using wasteland as the control, we conducted artificial simulated rainfall experiments on soils covered by Quercus variabilis, Platycladus orientalis, and shrubs, with three rainfall intensity gradients. Key findings showed that Platycladus orientalis exhibited the strongest infiltration capacity and longest runoff initiation delay due to its high proportion of stable macroaggregates (>0.25 mm), while barren land readily formed surface crusts, leading to the fastest runoff. Increased rainfall intensity significantly exacerbated runoff and erosion. When the macroaggregate content exceeded 60%, sediment yield rates dropped sharply, with a significant negative exponential relationship between the mean weight diameter (MWD) and sediment yield; barren land (dominated by microaggregates) faced the highest erosion risk and fell into an erosion–fragmentation vicious cycle. Redundancy analysis revealed that microbial communities (e.g., Ascomycota) and fine roots were dominant erosion-controlling factors under heavy rainfall. Ultimately, the synergistic system of the macroaggregate architecture and root-microbial cementation enabled Platycladus orientalis and other tree stands to reduce soil erodibility via maintaining aggregate stability, whereas shrubs and barren land amplified rainfall intensity effects. barren landbarren landmm·h⁻¹ mm·h⁻¹ mm·h⁻¹ barren land. Full article

This study examines the kinematic behavior of a large-scale colluvial landslide in a coastal low-elevation forest, where rainfall, geological formations, and hydrological conditions drive substantial slope displacement. The landslide comprises a colluvial layer overlying mudstone, with downslope movement toward the coastline induced by gravitational forces and infiltration. Using GPS surveys, inclinometers, soil moisture sensors, and numerical modeling, the temporal and spatial patterns of displacement were analyzed. Maximum horizontal displacements reach 8.1 cm/year, with deep-seated movements extending over 25 m into the mudstone. Key mechanisms include weakening of the colluvium–mudstone interface and creep within saturated mudstone, while a hydraulic barrier near the coastline restricts subsurface flow. Progressive upslope migration of the freshwater-bearing mudstone zone under annual rainfall further contributes to long-term deformation. These findings provide critical insights into the hydrologically controlled kinematics of coastal colluvial landslides. Full article

Water resources are a crucial foundation, and their importance increases in dry and semi-arid environments. Given the constraints of water resources, increasing population needs, and the processes of evaporation and infiltration, it is imperative to explore strategies to optimise rainfall, noted for its abruptness and quick accessibility. Constructing small dams is one of the most effective methods for harvesting rainwater in the Iraqi Western Desert. This will conserve water throughout the arid season. The study’s goal was to assess and enhance rainwater harvesting (RWH) performance across diverse design and management scenarios, utilising a novel water-harvesting model (WHCatch) for testing at the sub-catchment level. Rainfall data from two dams in Wadi Horan from 1990 to 2019 were included in the model. This study emphasises the advantages of modelling long-term water balances at the sub-catchment level and proposes strategies for optimising rainwater harvesting to enhance understanding of the hydrological processes inside the rainwater harvesting system. Substantial enhancements in RWH performance were attained by modifying the heights of the spillway (2 m) and the flow directions, yielding 90% and 85% increased storage for the Horan/2 dam and the Horan/3 dam, respectively. In practice, this provides guidelines for creating and implementing low-cost, minor dam modifications as well as for establishing seasonal release schedules that satisfy downstream and storage requirements. The findings are consistent with policy-level support for sustainable development goals in arid regions. Full article

Urban flooding caused by short and high-intensity rainfall events presents increasing challenges for cities, threatening infrastructure, public safety and economic activity. Accurately representing infiltration processes in hydrodynamic models is critical, as oversimplifying infiltration can lead to significant errors in predicted flood extents and water depths. This study systematically compares two widely used infiltration models—Green-Ampt and Curve Number—implemented within two leading 2D hydraulic models, HEC-RAS and IBER, to assess their influence on urban flood predictions. Simulations were conducted for 26 rainfall events, including both observed and synthetic hyetographs, across two urban neighbourhoods in Pamplona metropolitan area, Spain. Model performance was evaluated using root mean square error, mean absolute error and confusion matrix-derived metrics such as precision, accuracy, specificity, sensitivity and negative predictive value. Results indicate that the choice of infiltration method significantly affects both water depths and inundation extents: while Green-Ampt yields more conservative water depth estimates, Curve Number tends to underestimate flood extents. The comparison between the two hydraulic models has shown that IBER simulates broader flood extents and lower water depth errors compared to HEC-RAS. The findings highlight the importance of selecting appropriate infiltration methods and hydraulic models for reliable urban flood risk assessment, as well as providing guidance for model selection in urban inundation studies. Full article

Water scarcity is a significant issue in arid and semi-arid regions and improving our understanding of infiltration and recharge processes is crucial for water resource management. In this study, weighing lysimeters were employed in Mu Us Sandy Land, China to continuously monitor soil water content and recharge rates during the non-freezing seasons from April 2021 to October 2023. The performance of three empirical weight functions, including Poisson, Rayleigh, and Gamma distributions in simulating the recharge process was evaluated. The results indicate that: (1) The process of groundwater recharge displays significant interannual and seasonal differences. Due to low initial soil moisture and scarce rainfall, recharge accounts for only 10.9% of the averaged annual rainfall in 2021. Due to extreme rainfall events (126.8 mm), groundwater recharge increased by 649.4% compared to 2021, accounting for 51.2% of the annual rainfall in 2022. Because of relatively high soil moisture, groundwater recharge accounted for 18.3% of the annual rainfall in 2023. (2) The Poisson empirical weight function is more suitable for simulating a gradual increase in recharge rate, while it fails to accurately capture the rapid rise in recharge rates associated with extreme rainfall events. (3) Compared to the Poisson empirical weight function, the Gamma distribution performs better under extreme rainfall conditions. This study provides a detailed analysis of groundwater recharge dynamics in semi-arid regions and offers technical support for a deeper understanding of groundwater recharge processes. Full article

Slope stability monitoring and evaluation are key means to ensure the safety of engineering projects. Firstly, the classification, principles, and characteristics of distributed fiber optic sensing technology for slope engineering are introduced, and the significant advantages of this technology in slope monitoring are analyzed. Secondly, taking the Three Gorges Reservoir landslide as a case study, laboratory experiments of slopes were conducted using spatiotemporally continuous fiber optic neural sensing technology. Through the slope physical model experiment under loading excavation and rainfall conditions, it is found that (1) the strain changes monitored by vertically laid sensing cables are more sensitive to loading (with a peak strain of about 1400 με), while horizontally laid optical cables are more sensitive to excavation processes (with a peak strain of about 8900 με). Specifically, the tension–compression strain transformation in horizontally laid sensing cables can be used to identify slope failure in advance. (2) Rainfall infiltration significantly weakens the strength of the slope soil. Only considering the loading situation, the slope experiences instability and failure under a load of 120 kg. Under the premise of the soil saturation caused by rainfall infiltration, the slope experienced instability and failure under a load of 20 kg. Therefore, compared to human engineering activities, rainfall has a more significant impact on the stability of the slope. This study sheds light on the slope failure mechanism and provides a scientific basis for early warning. Full article

This study examines the deformation and failure mechanisms of two reservoir bank landslides: the traction-type Baijiabao landslide and the translational Baishuihe landslide. Based on long-term monitoring data and a hydro-mechanical coupled numerical model of rainfall infiltration, we investigate the impact of crack depth on landslide stability. Results show that the Baishuihe landslide exhibits translational failure, initiated at the rear by tension cracks and rear subsidence, followed by toe uplift, whereas the Baijiabao landslide displays traction-type progressive failure, starting with toe erosion and later developing rear-edge cracks. Rainfall induces similar seepage patterns in both landslides, with infiltration concentrated at the crest, toe, and convex terrain areas. As crack depth increases, soil saturation near the cracks decreases nonlinearly, while the base remains saturated. However, displacement responses differ: Traction-type landslides exhibit opposing lateral movements with minimal vertical displacement. In contrast, translational landslides show displacement increasing with crack depth, dominated by gravity. These findings guide targeted mitigation: traction-type landslides require crack control and toe protection, while translational landslides need measures to block thrust transfer and monitor deep slip surfaces. This study offers new insights into the effect of crack depth on landslide stability, contributing to improved landslide hazard assessment and management. Full article

Investigating rainfall infiltration mechanisms and slope stability dynamics under varying vegetation cover conditions is essential for advancing ecological slope protection methodologies. This research focuses on large-scale outdoor slope models, with the objective of monitoring soil moisture variations in real-time during rainfall events on four types of slopes: bare, herbaceous, shrub, and mixed herb–shrub planting. Combining direct shear tests for unsaturated soil with numerical simulations, and considering the weakening effect of water on shear strength, this study analyzes slope stability. The findings reveal significant spatial variations in rainfall infiltration rates, with maximum values recorded at a burial depth of 0.2 m, declining as the burial depth increases. Different types of vegetation have distinct impacts on slope infiltration patterns: herbaceous increases cumulative infiltration by 21.32%, while shrub reduces it by 61.06%. The numerically simulated moisture content values demonstrate strong congruence with field-measured data. Compared with monoculture herbaceous or shrub root systems, the mixed herb–shrub root system exhibits the most significant enhancement effects on shear strength parameters. Under high water content conditions, root systems demonstrate substantially greater improvement in cohesion than in internal friction angle. Before rainfall, shrub vegetation contributed the most significant improvement to the safety factor, increasing it from 2.766 to 3.046, followed by herbaceous and mixed herb–shrub vegetation, which raised it to 2.81 and 2.948. After rainfall, mixed herb–shrub vegetation demonstrated the greatest enhancement of the safety factor, elevating it from 1.139 to 1.361, followed by herbaceous and shrub vegetation, which increased it to 1.192 and 1.275. The study offers preliminary insights and a scientific basis for the specific conditions tested for selecting and optimizing eco-friendly slope protection measures. Full article