Channel Erosion Research Articles

The blockage and erosion characteristics of woody debris flow on an erodible gully bed: Insight from a small-scale model experiment

During the transportation process of debris flow with large wood (LW), phenomena such as channel blockage and collapse frequently occurs, resulting in increased discharge surges, heightened erosion intensity, and amplified damage. Accurately predicted the blockage performance is the basis of evaluating the damage and disaster mitigation of woody debris flow. In this study, we conducted a series of laboratory experiments of woody debris flow on erodible gully bed. The experiment results show that the final blockage types can be divided into three types: non-blockage, blockage, and semi-blockage. Temporary blockage will cause abundant sediment deposited temporarily and then released instantaneously, resulting in destructive surges and eventually lead to semi-blockage and non-blockage. The blockage degree is positively correlated with the relative length, relative content of LW, and bulk density of debris flow, but negatively correlated with slope. Channel blockage is often accompanied by significant local erosion effect, and the erosion depth of downstream channel increases with the increase in blockage degree. The blockage and collapse mechanism of woody debris flow was analyzed, and the results emphasized that channel erosion promoted the outbreak of blockage collapse. Based on the analysis of blockage performance, we propose an improved blockage criterion F to evaluate the blockage degree, and the high probability range of temporary blockage is determined as 1.5–5.0. The results can provide reference for the risk assessment and mitigation of woody debris flow.

Why do people dislike inflation? The role of missing debt erosion channel

ABSTRACT This paper conducts a survey on the preferred inflation rates among Japanese consumers. People’s optimal inflation rate is −0.55% on average, which is below the 2% target of the Bank of Japan. To delve deeper into the cause of people’s aversion to inflation, this paper conducts an information provision experiment with three group. While the two treatment groups are provided with information that inflation could erode the amount of savings or debt, the control group is not provided with any information about erosion. We then examine the impact of the information provision on people’s optimal inflation rate. The findings are as follows. First, providing information on debt erosion increases people’s optimal inflation rate by about one percentage point. Second, the above is only observed among debt holders, particularly high debt holders. Third, providing information on savings erosion does not significantly affect people’s optimal inflation rate, even for those with high savings. These results suggest that the failure to understand the debt erosion channel of inflation could partly explain people’s aversion to inflation.

Seismic geomorphology and reservoir conditions of a Middle Miocene submarine channel system in the Taranaki basin, New Zealand

Deepwater channels function as vital deep-sea hydrocarbon reservoirs and as major routes for moving terrestrial clastic sediment to deepwater environments. A high-resolution sequence stratigraphic framework was built for the deepwater area of the Taranaki Basin using high-resolution three-dimensional (3D) seismic data, and various seismic interpretation techniques, including seismic attribute analysis, were applied. The principal controlling factors and petroleum development potential of the Middle-Miocene channel system were investigated with sequence stratigraphy and seismic geomorphology. Four understandings were primarily attained in this study: (1) depending on the different levels of the channel surfaces, the channel system can be divided into five sedimentary units (SU1-SU5), which correspond to the five stages of channel system evolution. These surfaces include one primary draping surface (PDS), five secondary channel erosion surfaces (SCES), and several tertiary channel erosion surfaces (TCES). (2) with the use of seismic facies analysis, six sedimentary elements were identified in the channel system: pelagic deposits (PDs), mass transport deposits (MTDs), outer levee complex (OLC), inner levee and terrace complex (ILTC), and turbidite channel complexes (TCCs). (3) The sedimentary evolution of the channel system was jointly influenced by multiple factors. The sediment supply and submarine geomorphology can directly affect the internal stacking and migration patterns of the channel. In contrast, tectonic activity and relative sea level fluctuations can indirectly affect the sedimentary characteristics of the channel by regulating the components and scale of clastic sediment. (4) SU1, SU2, and SU3 are primarily filled with coarse-grained sediments, which can serve as high-quality hydrocarbon reservoirs. In contrast, SU4 and SU5 can serve as regional cap rocks because they are filled with fine-grained sediments, and the overall channel system can represent a potential hydrocarbon reservoir-cap combination, which can be viewed as a significant research target for upcoming deepwater exploration. Clarifying the sedimentary properties and primary controlling factors at the various evolutionary stages of deepwater channels is vital for predicting the hydrocarbon development potential of the basin and reducing the drilling risk. This also helps with the development of deepwater basins with similar sedimentary environments in New Zealand and elsewhere in the world.

Quantifying the Geomorphological Susceptibility of the Piping Erosion in Loess Using LiDAR-Derived DEM and Machine Learning Methods

Soil piping erosion is an underground soil erosion process that is significantly underestimated or overlooked. It can lead to intense soil erosion and trigger surface processes such as landslides, collapses, and channel erosion. Conducting susceptibility mapping is a vital way to identify the potential for soil piping erosion, which is of enormous significance for soil and water conservation as well as geological disaster prevention. This study utilized airborne radar drones to survey and map 1194 sinkholes in Sunjiacha basin, Huining County, on the Loess Plateau in Northwest China. We identified seventeen key hydrogeomorphological factors that influence sinkhole susceptibility and used six machine learning models—support vector machine (SVM), logistic regression (LR), Convolutional Neural Network (CNN), K-Nearest Neighbors (KNN), random forest (RF), and gradient boosting decision tree (GBDT)—for the susceptibility assessment and mapping of loess sinkholes. We then evaluated and validated the prediction results of various models using the area under curve (AUC) of the Receiver Operating Characteristic Curve (ROC). The results showed that all six of these machine learning algorithms had an AUC of more than 0.85. The GBDT model had the best predictive accuracy (AUC = 0.94) and model migration performance (AUC = 0.93), and it could find sinkholes with high and very high susceptibility levels in loess areas. This suggests that the GBDT model is well suited for the fine-scale susceptibility mapping of sinkholes in loess regions.

Evaluating the continued significance of dam-induced vigorous downstream channel erosion in the context of projected climate change: a case study from Peninsular India

ABSTRACT Although erosion has naturally been driven by rainfall patterns, human activities have increasingly influenced erosion rates in recent times. However, as climate change alters precipitation, future erosion control may once again depend primarily on climate. The primary goal of this investigation was to ascertain whether the issue of escalated erosion, typically linked to downstream dam effects, could diminish in significance due to projected climatic shifts later in this century. An erosion potential index (Ep), formulated as the ratio of the mass of sediment influx from upstream to the frequency of the sediment-carrying flow events, was computed on a tributary of the Godavari River, located downstream of a dam. Using the Soil & Water Assessment Tool (SWAT), virtual experiments were conducted to distinguish the impacts of the dam from projected climate changes on river geomorphology. Two control scenarios were created using the current climate data and simulated regulated and unregulated states of the basin. Employing climate projections and various mitigation scenarios (SSPs) for the 2060s and 2090s, this study estimated Ep values exclusively under future climatic conditions in an unregulated state of the basin. Results indicate that, in the unregulated state without the existence of the upstream dam, future climate impacts on erosion outweigh the current effects of the dam, underscoring the growing influence of climate on geomorphology. It suggests that existing structural interventions may lose their geomorphic significance in the face of future climate conditions.

Characterization of a deep-water turbiditic reservoir under an active hydrodynamic regime (Niger delta)

The Egina Field, situated in the deep-water region of the eastern Niger Delta, is characterized by a NE-SW trending anticline that contains several Middle to Upper Miocene stacked reservoirs. Notably, one of the reservoirs in the field includes three sandy intervals, which have been identified as deep marine turbidite systems. The lowest level (Interval 1) comprises a lobe complex, while the uppermost Intervals 2 and 3 consist of erosive channel complexes. These three reservoir intervals exhibit both static and partial dynamic communication. The Egina Field is affected by a coherent network of extensional and oblique-slip faults, with current activity confined to the eastern sector of the structure. Large displacement faults (throw >30m) offset individual reservoir intervals, creating lateral disconnection and acting as barriers to fluid flow across faults. Minor NNE-SSW oriented faults can locally baffle the flow of fluids, as evidenced by well tests and 4D seismic data. Nonetheless, well interference tests suggest good communication within the reservoir. Vertical communication between the stacked sand bodies is facilitated through erosional contacts between reservoir intervals, while lateral communication occurs around segmented faults, via relay ramps and fault tips, in a NE-SW direction. Across the field, ten oil-water contacts have been identified, with a general trend of deepening towards the south. This pattern has been interpreted as a tilted contact caused by an active hydrodynamic regime, where aquifer overpressures gradually decrease from north to south (31 m of difference), aligning with the regional trend. This paper describes how the geological (structural and sedimentological) heterogeneities are paramount in deep-water turbiditic reservoirs, for both static and dynamic conditions. The work presented here shows how the geological analysis can impact reservoir management, driving strategic decisions on field development, as such as the identification of infill wells opportunities or the optimizing the placement of injectors wells, to effectively support producers.

The outburst of dammed lake Maashey (North-Chuya ridge, Central Altai)

The dammed lakes are widespread in mountainous areas and usually occur when river flow is blocked by landslides, rock glaciers, etc. Among such lakes, the most dangerous are those located in the periglacial zone and blocked by rock glaciers. Continued deglaciation of mountainous areas under changing climate conditions contributes to accumulation of large volumes of melt water in lakes, which may increase pressure on the dam, cause its failure and subsequent outburst flood. In this article we describe the development of such a lake before its outburst and the process of its outburst. The object of study was Maashei Lake (North Chuya Ridge, Central Altai) located in the zone of mountain glaciation and dammed by a rock glacier, where the lake outburst occurred in July 2012. The lake area before the outburst was 259 × 103 m2 and water volume 1.21 × 106 m3. As a result of the outburst, the lake was completely drained. We analyzed the published works on Lake Maashei, materials of our own field studies in the lake basin combined with remote sensing data. We hypothesized that the mechanism of the outburst occurred in 2012 was caused by the water erosion of the filtration channel in the dam body. The mechanism of this outburst was numerically simulated using the method presented in this article. The modeling allowed to reproduce the outburst flood hydrograph, to estimate such characteristics as maximum water discharge, volume of the outburst flood, water flow velocities and the size of the formed breach. Estimated maximum discharge was 694 m3s−1, flow velocities varied from 0.2 to 5-7 m s−1, and the outburst flood period was about 5.5 hours. The breach was formed to the full height of the dam (10 m). Its calculated morphometric characteristics were as follows: average width 47.5 m (measured 41.5 m), скоss-section area 476 m2 (measured 415 m2). The discrepancy between the modeled and measured values was about 15%.

FastFlow: GPU Acceleration of Flow and Depression Routing for Landscape Simulation

AbstractTerrain analysis plays an important role in computer graphics, hydrology and geomorphology. In particular, analyzing the path of material flow over a terrain with consideration of local depressions is a precursor to many further tasks in erosion, river formation, and plant ecosystem simulation. For example, fluvial erosion simulation used in terrain modeling computes water discharge to repeatedly locate erosion channels for soil removal and transport. Despite its significance, traditional methods face performance constraints, limiting their broader applicability.In this paper, we propose a novel GPU flow routing algorithm that computes the water discharge in 𝒪(log n) iterations for a terrain with n vertices (assuming n processors). We also provide a depression routing algorithm to route the water out of local minima formed by depressions in the terrain, which converges in 𝒪(log2 n) iterations. Our implementation of these algorithms leads to a 5× speedup for flow routing and 34 × to 52 × speedup for depression routing compared to previous work on a 10242 terrain, enabling interactive control of terrain simulation.

Coupled computational fluid dynamics-discrete element method for simulating the interactions between ship-induced waves and riprap on restricted waterway banks

In inland waterways, waves generated by passing boats cause the movement of riprap used for bank protection and stabilization. Previous studies have mainly concerned the natural channel erosion problem caused by wind-generated waves and neglected the research and findings on shipping behavior. This work presents a coupling of the computational fluid dynamics model and the discrete element method. The aim is to first study the interactions between ship waves in the confined channel and the movements of the riprap of the banks and shorelines and second to analyze the stability of these armourstones under the actions of various ship velocities and draught depths. These varying conditions exert influence on the ship-induced waves, the crucial point being the drawdown amplitude, and consequently create more intense flow behavior in the near-shore region, which results in instability and destruction of the overall structure of the armor protection layer. The higher ship velocity and the larger draught depth lead to the aggravation of instability processes of the blocs composing the protective layer. There is a critical phenomenon in the influence mechanism of vessel velocity, whereas the variation process induced by draught depth is relatively linear. In addition, the stability of the blocs also depends on their shapes, sizes, and the initial positions within the protective layer. This study could contribute to the high-quality development of inland navigation.

Mio-pliocene evolution of deep-water channels on the northeastern Bengal fan: Records of signals of Himalaya uplift and South Asian Monsoon from source areas

Submarine channels, acting as major conduits for delivering terrestrial sediments into the deep sea, are sensitive to source-region uplift and climate variations. Using new 3D seismic data, previously published paleoenvironmental data, and IODP/ODP data, we characterize stratigraphic time changes in deep-water channels on the northeastern Bengal Fan and suggest that their long-term evolution relates to contemporaneous changes of Himalaya uplift and South Asian Monsoon. Our results show that around the boundary between the Miocene and Pliocene Epochs, the sedimentary characteristics of deep-water channels were changing at about the same time as decreased rates of Himalaya uplift and changes in the monsoonal climate. It is strongly suggested that environmental signals could successfully propagate from the Himalaya to the deep sea and play a dominant control on the long-term evolution of deep-water channels. During the late Miocene, orogen-wide and substantial Himalaya uplift and humid monsoonal climates (dominance of summer monsoon) generated a sediment supply with high fluxes, which allowed coarser-grained sediments to reach further into the basin and thus caused the formation of larger-scale, non-leveed erosional channels that have avulsion and confluence phenomena. After the Miocene, local and limited Himalaya uplift and arid monsoonal climates (dominance of winter monsoon) led to a sediment supply with low fluxes, during which only finer-grained sediments reached deep water and gave rise to smaller-scale, leveed aggradational channels that mainly have splay deposits. Between the late-Miocene and post-Miocene periods, detrital zircon U-Pb ages of Bengal Fan samples from IODP cores reflect a sediment provenance change from the mixing of Brahmaputra and Ganges Rivers to the end-member of Brahmaputra River, broadly coeval with the variations of Himalaya uplift and South Asian Monsoon. Moreover, Bengal Fan cores record a Mio-Pliocene decrease in sedimentation rates and maximum grain sizes and an increase in mudstone contents, consistent with the variations of sediment yield in the source catchments. Observations and interpretations from the current study, therefore, contribute to a better understanding of how the long-term evolution of submarine channels respond to tectonic and climatic perturbations in source areas and may help recognizing similar process-response relationships in other areas.

Impact and erosion dynamics of inclusion-enriched dry granular flows on rigid barriers with basal clearance: Numerical insights from hybrid MP-DEM simulations

Rigid barriers with basal openings are often installed along predicted flow paths to protect downstream facilities from dry granular flows containing large boulders. However, current design practices do not consider the effects of these inclusions during impact, discharge, overflow, and bed erosion. We conducted hybrid MP-DEM simulations to study the dynamics of dry sand flow with inclusions impacting a rigid barrier with a basal opening. Our findings show that accounting for large inclusions is crucial for barrier design, as they alter dry granular flow regimes, delay dead zone formation, and affect overflow dynamics. Current analytical solutions may overestimate velocity attenuation by up to 60% if inclusions are not considered. A 10% increase in inclusion volume fraction leads to 6%-28% increases in internal energy dissipation during overflow, resulting in an overflow distance 20% lower than existing predictions. Additionally, channel bed erosion due to landing flow with inclusions creates a flow depth up to 3.5 times thicker than at the first barrier location. This suggests that using the initial flow depth for impact force assessment on a second barrier may not be conservative for erodible channel beds and inclusion-enriched flows.

The timing of Missoula floods: Implications for the age of Grand Coulee (eastern Washington, USA)

The Channeled Scabland of eastern Washington (USA) was formed by outburst floods from glacial Lake Missoula. Despite chronological advances, the timing of erosion in the main flood channels is unresolved. In particular, it is still uncertain whether upper Grand Coulee, the largest canyon in the Channeled Scabland, was incised during or prior to the last glaciation. We report 10Be exposure ages from erratics in upper Grand Coulee, glacial Lake Columbia, and surrounding flood routes. Flood-transported boulders on the high-elevation east rim of Grand Coulee date to ca. 17−15 ka. Ages from boulders on the floor of Grand Coulee indicate later flooding at ca. 14 ka, which post-dated canyon incision and occurred after inundation of the Telford-Crab Creek scabland at ca. 15−14.5 ka. Prior hydraulic modeling and dating suggest the entrance to Grand Coulee was blocked by rock and that canyon incision was incomplete at ca. 17 ka; hence, we interpret the 17−15 ka exposure ages on the east rim to coincide with flow over a retreating cataract during canyon incision. Our results indicate incision of Grand Coulee was completed between 17 ka and 14 ka. The short duration of canyon incision suggests that glacial Lake Missoula generated some of the most erosive outburst floods in Earth’s history.

Impacts of bridge constructions on channel dynamics and sediment aggradation: An integrated discussion, West Bengal, India

Channel dynamics, including channel migration, erosion, and deposition, is a significant geomorphological phenomenon. It has been noted that the Gish River exists with its widest extension between 1913 and 2021, causing a bottleneck situation. The section G4 (Gish-4) experienced the most significant squeezing character over time. The catchment landslide-induced sediments, mostly transported in the monsoon by 1st and 2nd order streams, deposited at the beds near the rail and road bridges of the rivers Lish, Gish, and Chel. Landslide susceptibility mapping (LSM) and sediment transport index (STI) maps specify the zones of sediment generation and aggradation. Results of low ‘b” value 0.77 + /−0.04 specify active tectonics and instability of the area. A petrographic analysis of landslide samples and river bed sediments justifies that the landslide connected streams are continuously transported and deposited in the river bed. In the Himalayan foothill rivers like Lish, Gish, and Chel, channel planform dynamics may be the result of landslide occurrences, that induce huge sediments in the rivers and sediment transport index indicates the deposition of the sediments near rail and road bridges in spatio-temporal scale.

Defining and characterizing the phenomenon of river-bottom tearing scour (RBTS): A case study of the Middle Yellow River

River-bottom tearing scour (RBTS) in natural rivers refers to the incipient motion and transport processes of clay blocks formed by fine cohesive sediment after deposition and consolidation in riverbeds. The RBTS phenomenon can lead to significant channel erosion and changes in river planview morphology, and has, thus, attracted the attention of hydrologists and engineers. In the study, a new determination measure (K) for the occurrence of a RBTS event is derived based on the theoretical expression for the critical incipient velocity of the clay block, K=α2(CL+2λ22), which is a combination of the coefficients of the velocity (i.e., α is a local velocity coefficient), lift force (i.e., CL is the lift coefficient), and clay block size (i.e., λ2 is the ratio of block thickness to length). Furthermore, to explain river behavior during a RBTS event, the Fugu, Xiaobeiganliu, and Weihe river reaches in the Middle Yellow River (MYR) were selected as study areas. Analysis of hydrological data from 1950 to 2023 in the examined reaches implies that a single discharge or sediment threshold cannot predict the occurrence of RBTS. The cross-sectional erosion and deposition volume (CEDV) and the migration intensity of the channel thalweg (MI) also were calculated at the section and reach scales for the examined reaches during the RBTS events. It was observed that RBTS typically causes significant channel erosion originating from the most upstream portion of the study reach with CEDV values ranging from 61 to 6034 m2, while MI values during the RBTS events were close to the multi-year average for the study reach. Finally, a flume experiment simulating RBTS was done to discuss and verify the threshold value of K. Field survey and experimental results indicated that RBTS occurs if K > 0.5, thus, providing theoretical support for the prediction and prevention of RBTS.

Geomorphic evolution of Sutlej valley catchment in Western Himalayas: Imprint of surface processes in modulating fluvial erosion

The Sutlej River catchment in the tectonically active western Himalayas has several geomorphic signatures of river piracy and drainage reorganization across the Upper Sutlej-Zhada basin upstream. The accelerated growth of the Leo-Pargil Horst across the Kaurik Chango-fault (KC-fault) Zone and affected regional tectonics triggered enormous incisions, causing southward migration of the present Sutlej River, which is highly infested by bedrock landslides and debris flows and evolves as a very steep valley catchment. In order to understand the changing regional landscape and identify the tectonic perturbation over the channels, we evaluate the slope-break knickpoints in the Sutlej River profile. Furthermore, we model the presence of an elevated low-relief relict landscape in the Upper Sutlej-Zhada basin and the rapid incising lower Sutlej valley catchment using the Celerity model. The observation suggests that major knickpoints at ~2000–3000 m elevation comprise the fluvial erosion process, while higher elevation knickpoints recommend the hillslope process. In order to understand how fluvial erosion and surface process imprints have changed the landscape over time, we spatially correlate terrestrial datasets, such as rates of denudation and exhumation ages, with topographic metrics and climate variables. We observe a strong correlation between the pattern of denudation rates and the conditioning factors that modulate the surface processes. Increased channel erosion, high stream power, topographic metrics, and the occurrence of bedrock landslides over a regional structural disruption exhibit a positive spatial relationship, but their role in regional drainage capture, tectonic uplift, and the gradation process remains poorly understood.

Estimating the effect of sand-roughened bed on hydraulic jump characteristics using heuristic models

The hydraulic jump occurs in open channels and downstream of hydraulic structures because these features change the flow regime from super-critical to sub-critical. To prevent downstream channel erosion and guarantee the construction of a hydraulic jump, a stilling basin is utilized. The effect of sand-roughened beds on hydraulic jump characteristics was investigated using an experimental study. After that, new machine learning models including Emotional neural network (EANN), Hammerstein Weiner model (HWM), Elman neural networks ENN, and Extreme learning neural networks (ELNN) were adopted to estimate the ratio of hydraulic jump length to initial water depth. Different evaluation criteria such as determination Coefficient (R2), Mean Square Error (MSE), Correlation Coefficient (R), and Rout Mean Square Error (RMSE), scatter plots, time series comparison, and Spiral plots have been used to evaluate the models' performance. The results revealed that the Elman NN model outperformed the other models in estimating the ratio of hydraulic jump length to the initial depth (Lj/y1), while the HWM model has a weaker performance than other models in estimating Lj/y1.

Spatio-temporal analysis of riverbank changes using remote sensing and geographic information system

Fluvial hazards cause severe damage to human lives and properties. The increased intrusion of anthropogenic activities into natural hydrological cycles has increased hazard severity and confounded river channel dynamics. The present article studies the epochal channel erosion, accretion, and unaltered sites along the 42 km stretch between the Polavaram project and Dowleshwaram Barrage on the Godavari River. Geographic Information System (GIS) and Remote Sensing (RS) techniques were used to identify changes in river morphology. A total of five decades of Landsat images were analyzed, classifying the land use with a supervised learning Support Vector Machine (SVM) algorithm and an ISO cluster unsupervised algorithm to delineate the rivers and study the influence of land use land cover change (LULCC) on river morphology. Accretion and erosion channel changes during the assessment period were measured at all reaches, and the possible driving mechanisms of morphological alterations were studied.The results indicate the susceptibility of human dwellings and agricultural lands to floods due to the shifting of the highly vibrant river shoreline. The study provides the most recent information on Godavari River dynamics. These aspects of the river's evolution will aid in planning and management in the lower portions, which have not been well understood. River channel alterations can be quantitatively and economically analyzed using Remote Sensing (RS) and Geographic Information System (GIS) data.

Migration and erosion in tidal and river channels in Bangladesh

Environmental stressors and natural disasters are changing the physical landscapes in many countries worldwide. In this paper, we ask whether and how erosion affects internal and international migration in Bangladesh. Building on prior studies, we use data from 3,600 households in 18 research sites to investigate how erosion in tidal and river channels is related to the risk of making a first internal or international trip, net of extreme weather conditions and other relevant attributes. Findings reveal that the relationship between erosion and the likelihood of making a first domestic or international trip is moderated by livelihood type and landownership. As erosion worsens, the odds ofmaking a first domestic trip rise for non-agricultural non-landowning household heads and decline for landowners working in agriculture. Estimated lifetime probabilities of making a first domestic trip are higher than those of making a first international trip, with non-agricultural non-landowners having the highest probabilities and agricultural landowners having the lowest. Together, the evidence suggests that shifts in physical landscapes, especially erosion, are tightly linked to out-migration through ties to land.

Study on the stressing state features of basalt fibre concrete lining structure under sulphate erosion

Basalt fibre (BF) is an environmentally friendly material with excellent corrosion resistance. When tunnels cross gypsum rock strata, the gypsum rock will dissolve sulphate and erode the supporting structure, thus affecting the safe operation of the tunnels in the long term. Adding BF to the supporting structure of gypsum rock tunnels can improve its resistance to sulphate erosion. This paper took Wuzhishan Tunnel as a case, and first determined the sulphate concentration of the gypsum rock stratigraphic environment at the site; then, analysed the change of mechanical properties of basalt fibre concrete (BFC) before and after sulphate erosion by mechanical tests; finally, examined the deformation and force characteristics of the BFC secondary lining structure by numerical simulation. The results showed that the bridging effect of BF fibres and the stable spatial network structure formed inside the concrete enhanced the mechanical properties of BFC and its ability to resist sulphate erosion. However, due to the agglomeration effect of BF fibres, too much BF would reduce the mechanical properties and erosion resistance of BFC. At a BF content of 6 kg/m³, BFC had the strongest ability to resist sulphate erosion, and the cube compressive strength, axial compressive strength, and modulus of elasticity of BFC were the highest, with 47.8 MPa, 33.6 MPa, and 38.7 GPa, respectively. The dense calcium silicate hydrate (C-S-H) gel, generated near the BF, enhanced the connection between the cementitious and the aggregate, inhibited the development of microcracks within the concrete, and reduced the erosion channels for sulphate ions. The maximum displacement of the BFC secondary lining structure was reduced by 20.15 % compared to plain concrete (PC) after sulphate erosion. The secondary lining structures consisting of both BFC and PC were stressed the most at footing. The secondary lining structure composed of BFC had better deformation resistance and higher strength than PC.

The Application of Remote Sensing Technology in Post-Disaster Emergency Investigations of Debris Flows: A Case Study of the Shuimo Catchment in the Bailong River, China

The Bailongjiang River Basin is a high-risk area for debris flow in China. On 17 August 2020, a debris flow occurred in the Shuimo catchment, Wen County, which blocked the Baishui River, forming a barrier lake and causing significant casualties and property damage. In this study, remote sensing, InSAR, field surveys, and unmanned aerial vehicle (UAV) techniques were used to analyze the causal characteristics, material source characteristics, dynamic processes, and disaster characteristics after the debris flow. The results showed that the Shuimo catchment belongs to low-frequency debris flows, with a recurrence cycle of more than 100 years and concealed features. High vegetation coverage (72%) and a long main channel (11.49 km) increase the rainfall-triggering conditions for debris flow occurrence, making it more hidden and less noticed. The Shuimo catchment has a large drainage area of 31.26 km2, 15 tributaries, significant elevation differences of 2017 m, and favorable hydraulic conditions for debris flow. The main sources of debris flow material supply are channel erosion and slope erosion, which account for 84.4% of the total material. The collapse of landslides blocking both sides of the main channel resulted in an amplification of the debris flow scale, leading to the blockage of the Baishui River. The scale of the accumulation fan is 28 × 104 m3, and the barrier lake area is 37.4 × 104 m2. The formation mechanism can be summarized as follows: rainfall triggering → shallow landslides → slope debris flow → channel erosion → landslide damming → dam failure and increased discharge → deposition and river blockage. The results of this study provide references for remote sensing emergency investigation and analysis of similar low-frequency and concealed debris flows, as well as a scientific basis for local disaster prevention and reduction.