Groundwater Rise Research Articles

SOURCES OF WATER POLLUTION AND NANOTECHNOLOGY-BASED WATER PURIFICATION TECHNIQUES

Despite the measures taken in recent years, one of the main reasons for the disruption of the ecological balance of our region is its proximity to countries with somewhat more strained ecosystems. In recent years, the rapid rise of groundwater in Baku city towards the surface should be considered a constant threat to metro stations and their tunnels. Previously, tunnels of the "Academy of Sciences," "Neftchilar," and "Koroglu" metro stations were flooded, and due to long-term oil leakage from the main oil pipelines, both oil and water entered the tunnels. A similar incident occurred in the oil pipelines passing near the Jeyranbatan reservoir. These kinds of events are always under control. Considering that the human body is made up of 80% water, we can imagine how harmful poor-quality water can be to health. Low-quality water not only harms humans but also damages the technical devices they use, such as kettles, dishwashers, and washing machines. It also causes clogging in water pipes. The only way to improve efficiency is to use the achievements of nanotechnology. One of the most promising directions in nanotechnology is associated with carbon nanotubes. Carbon nanotubes are structures made only of carbon atoms. Carbon nanotubes can be imagined as the tubular shape of a single molecular layer of graphite (graphene). Using the properties of nanotubes, they can be applied in water purification. With nanotubes, it is possible to produce drinking water from clouds in areas without water, and even turn seawater into drinkable water. Keywords. Groundwater, Nanotechnology, Heavy metals, Ecological balance, Mineralization, Underground waters

Investigating overlapping deformation patterns of the Beijing Plain by independent component analysis of InSAR observations

Due to policies such as groundwater extraction restrictions, water diversion, and water replenishment, groundwater levels in the Beijing Plain have generally risen. This has effectively alleviated ground subsidence, with some regions even experiencing uplift. Under these new water conditions, strata deformation also shows spatiotemporal heterogeneity, and the overlap of these multiple deformation patterns hinders the interpretation of ground deformation. In this study, we employed Satellite Interferometric Synthetic Aperture Radar (InSAR) to investigate the spatiotemporal heterogeneous deformation patterns and their influencing factors in the Beijing Plain. We utilized Independent Component Analysis (ICA) to effectively separate overlapping ground deformation patterns from InSAR-derived ground surface deformation. Four ground deformation patterns—approximately linear subsidence, approximately linear uplift, decelerating subsidence, and periodic deformation—were extracted. Their overlapping status and influencing factors were explored based on external hydrogeological data. Approximately linear subsidence represents the continuous compression of deep strata in areas with severe subsidence. Approximately linear uplift represents the rebound of shallow strata caused by water replenishment. Periodic deformation represents the ground’s response to precipitation and irrigation pumping. The ICA results benefit the estimation of the time lag between groundwater rise and strata rebound in the Beijing Plain, as well as the estimation of the increase in groundwater storage capacity in the Miyun-Huairou-Shunyi region. This study provides a new perspective for extracting deformation information from InSAR observations, gaining a deeper understanding of deformation patterns related to hydrogeological phenomena, and assessing the effectiveness of groundwater management and land subsidence control policies.

Distribution and Dynamics of Icings in the Selenga Middle Mountains

The paper presents the results of the study on icings in the Selenga middle mountains (Western Transbaikalia). Current and retrospective maps of their distribution have been drawn up, relevant data on the main morphometric characteristics, interannual spatial dynamics, and area variability have been obtained. Comparison of vector data on the location of the icings in different years, together with the materials obtained during field expedition studies, allowed us to preliminary assess their belonging to different genetic types. It has been established that in the Selenga Middle Mountains, the predominant icings are formed as a result of groundwater rise to the surface during the seasonal freezing of rocks. About 30% of the icings are associated with groundwater sources coming from deep aquifers (key icings), river water icings are very rare. The interannual variability of the size of icings is in sync with the hydration cycles, at the same time, there is a tendency for an increase in the total number of icings. At the same time, the number of very large icings has decreased 2 times as compared to 1990, while the number of medium and small icings has increased. These trends are a consequence of changes in the state of the natural environment under the influence of climatic processes (increase in air temperature) and anthropogenic factors, which influence on the intensity of the icing formation processes in the Selenga Middle Mountains is significant.

Storm surge, seawater flooding, and sea-level rise paradoxically drive fresh surface water expansion

Abstract Coastal storms and sea-level rise (SLR) are expected to increase seawater flooding in low-elevation coastal zones. High sea levels and seawater flooding can drive groundwater table rise via ocean-aquifer connections. These dynamics are often overlooked but can cause groundwater flooding and salinization hazards, increasing freshwater security challenges for coastal communities and driving ecosystem transgressions. Field data and numerical modeling were used to evaluate how heavy rainfall, storm surge, and seawater flooding and infiltration during Hurricane Fiona (September 2022) and projected SLR impact groundwater levels, inland surface waters, and saltwater intrusion on Sable Island National Park Reserve, Canada. During the passage of Hurricane Fiona, precipitation increased groundwater and pond levels before seawater flooded the beach. Seawater flooding and infiltration caused a sharp rise in beach groundwater levels, which in turn caused inland pond levels to rise without coincident direct inputs from precipitation or seawater. Model simulations reveal that seawater infiltration on beaches flooded the subsurface and drove the observed inland groundwater rise and freshwater pond expansion. Simulations of projected SLR show that seawater flooding will only inundate a small area of land along the coast; however, inland groundwater rise and flooding, which is less well-studied, may inundate up to 30 times more land area. Further, groundwater flooding driven by rising sea levels decreases hydraulic gradients and increases saltwater intrusion via freshwater lens (FWL) contraction. Findings demonstrate that seawater flooding from coastal storms and SLR paradoxically cause concurrent fresh surface water expansion but FWL contraction. This study provides new insights into the spatiotemporal dynamics of island freshwater resources and highlights that unseen and often overlooked groundwater-surface water exchanges are critical to consider when evaluating coastal flooding and groundwater salinization hazards and management strategies for low-elevation coastlines.

Snowmelt-mediated isotopic homogenization of shallow till soil

Abstract. The hydrological cycle of sub-arctic areas is dominated by the snowmelt event. An understanding of the mechanisms that control water fluxes during high-volume infiltration events in sub-arctic till soils is needed to assess how future changes in the timing and magnitude of snowmelt can affect soil water storage dynamics. We conducted a tracer experiment in which deuterated water was used to irrigate a plot on a forested hilltop in Lapland, tracked water fluxes of different mobility and monitored how the later snowmelt modifies the labelled soil water storage. We used lysimeters and destructive soil coring for soil water sampling and monitored and sampled the groundwater. Large spatiotemporal variability between the waters of different mobility was observed in the subsurface, while surface water flow during the tracer experiment was largely controlled by a fill-and-spill mechanism. Extensive soil saturation induced the flow of labelled water into the roots of nearby trees. We found that labelled water remained in deeper soil layers over the winter, but the snowmelt event gradually displaced all deuterated water and fully homogenized all water fluxes at the soil–vegetation interface. The conditions required for the full displacement of the old soil water occur only during a snowmelt with a persistently high groundwater table. We propose a conceptual model where infiltration into the soil and eventual soil water replenishment occur in three stages. First, unsaturated macropore flow is initiated via the surface microtopography and is directed towards the groundwater storage. The second stage is characterized by groundwater rise through the macropore network, subsequent pore water saturation and increased horizontal connectivity of macropores. Shallow subsurface lateral fluxes develop in more permeable shallow soil layers. In the third stage, which materializes during a long period with a high groundwater table and high hydrological connectivity within the soil, the soil water is replenished via enhanced matrix flow and pore water exchange with the macropore network.

Hydrologically sensitive carbonates: Tectonic and groundwater controls on synrift sedimentation in the Late Jurassic–Early Cretaceous of the western Cameros Basin, Northern Spain

AbstractBasin hydrology and subcrop are key controls on carbonate sedimentation in continental basins. Hydrologically sensitive carbonates can record groundwater fluctuations within an aquifer in deep time. Late Jurassic extension, footwall uplift, erosion and karstification of marine Jurassic carbonates in the western Cameros Basin (Spain) saw deposition of ?Upper Kimmeridgian‐Tithonian syntectonic alluvial fan deposits (Señora de Brezales Formation). Biogenic laminar calcretes and phreatophytic rhizocretions record roots exploiting capillary fringe groundwater. Progressive infill of rift topography and footwall erosion lowered sedimentary gradients and clastic supply during deposition of the ?Tithonian–Berriasian Rupelo Formation. Distal alluvial marls (Las Viñas Member) contain charophytes, with 2 m thick carbonate lenses at the top reflecting intermittent rise of groundwater in ponds on the basin floor. Stacked palustrine limestones with rare charophytes and laminar calcretes (Ladera Member) record overstep of seasonal carbonate wetlands onto basin margins and footwall highs with intense pedogenetic modification during lengthy seasonal exposure. Overlying Berriasian charophyte‐ostracod wackestones, displaying microkarst cavities and interbedded intraclastic conglomerates, with vivianite sauropod bones, footprints and polygonal desiccation cracks at the top (Mambrillas de Lara Member) record open lacustrine conditions with limited subaerial exposure and high water tables. Desiccation‐cracked limestones and marls with correlatable evaporite horizons (Rio Cabrera Member) contain marginal marine foraminifera and dasycladaceae at the top. Lagoonal conditions reflected transgression to seaward and intermittent marine connection via the Basco‐Cantabrian Basin. The distribution and thicknesses of hydrologically sensitive carbonates reflected onlap onto a faulted and karstified marine Jurassic carbonate pediment and the subtle influence on hydroperiod of fault (and potentially localised Triassic salt) controlled differential subsidence and transgressive groundwater rise. Hydrological facies evolution reflects progressive basin infilling and eustasy beyond. Transitions in this continental succession from clastic to carbonate facies and from closed to open hydrology record hydrological change over time rather than contemporaneous deposition under Walther's Law.

An Urban Lake Drainage Catena: Influences of Terrain, Soils, and Precipitation

Urban lake drainage systems are heavily impacted by terrain, soil characteristics, and precipitation, which influence water infiltration and groundwater movement. This study focused on the drainage catena around Lake Nokomis in Minneapolis, Minnesota, where local residents have experienced wet basements and yards. The primary goal was to identify the factors contributing to these water-related problems, particularly soil permeability and how it responds to precipitation. By conducting soil borings, using pressure transducers, and measuring saturated hydraulic conductivity (Kfs), the study compared upland and lowland areas. Findings indicated that upland soils, primarily composed of sandy fill, had much higher infiltration rates, with Kfs values ranging from 72.4 cm/hr to 149 cm/hr. In contrast, lowland areas characterized by lacustrine and organic soils exhibited significantly lower Kfs values, ranging from 1 cm/hr to 14.8 cm/hr. Between 2022 and 2024, wet and dry seasons occurred, yet recorded more than 127.5 cm of rain and snow water equivalent, further contributing to groundwater rise and surface water presence in low-lying regions. The study concluded that increased precipitation, coupled with specific hydrogeologic conditions, was the main factor causing elevated groundwater levels and surface saturation in these areas. To address these challenges, Minnesota's water management authorities are encouraged to implement strategies that consider the increasing magnitude and intensity of precipitation events due to climate change. Incorporating hydrogeologic assessments into urban planning is recommended to better manage water infiltration, reduce flood risks, and strengthen the resilience of drainage systems to changing climate patterns.

Integrated GIS-hydrologic-hydraulic modeling to assess combined flood drivers in coastal regions: a case study of Bonita Bay, Florida

Flooding poses a severe global threat, necessitating advanced methodologies to assess and manage its risks effectively. This study introduces a novel approach that integrates Geographic Information System (GIS) with hydrologic-hydraulic modeling to evaluate the combined drivers of current and future flood risks. The method is applied to the development Bonita Bay in southwest Florida. It occurs in a region highly susceptible to flooding due to its low elevation and proximity to tidal waters. The innovative integration of GIS with hydrologic-hydraulic models enables detailed assessment and visualization of flood inundation areas under multiple flood drivers including design storms, land use changes, groundwater rise, and sea-level rise. This allows for the seamless simulation of complex flood interactions with only minor adjustments to the model for the identified drivers. The results indicate significant increases in initial water storage caused by sea and groundwater level rise and amplified storm runoff from land use changes. A 2% increase in flooded areas is projected with stronger design storms, and a 5% increase by 2,100 compared to 2024. This approach provides a robust framework for developing tailored flood mitigation strategies and can be adapted to various coastal regions globally.

Investigation of landslide triggers on Mount Oku, Cameroon, using Newmark displacement and cluster analysis

BackgroundThe landslide inventory of the western flank of Mount Oku, Cameroon, includes spreads or complex landslides, indicating sudden soil weakening, possibly due to seismic activity or heavy rainfall causing groundwater rise. These landslides were likely triggered between 2009 and 2018 based on the dates of the aerial imagery. Identifying triggers for past landslides remains a major unresolved issue in landslide science. However, understanding these triggers is crucial for accurately assessing future landslide hazards.MethodologyIn this paper, we investigate the possibility of earthquakes to precondition landslide development or reactivation during climatic events. By assuming a magnitude 5.2 earthquake, an epicenter of 10 km from this area, and different wetness conditions, the factor of safety (FS) and Newmark displacement (ND) models were calculated for shallow and deep-seated landslides with sliding depths of 3 and 7.5 m. Afterward, the relationship between FS, assumed ND, and observed landslides was analyzed in a cluster analysis, to derive patterns of climatically and seismically triggered landslides.ResultsThe comparison of FS maps and FS values of the observed landslides revealed that especially for landslides at 7.5 m depth, most sites that are stable during dry conditions become instable under saturated conditions, indicating a climatic trigger. At 3 m depth, however, some landslide sites that are still marginally stable under saturated conditions, display relatively high ND values for the investigated hypothetical earthquake, indicating a possible seismic influence. In the cluster analysis, we clustered the observed landslides according to their distances to rivers and topographic ridges and obtained three clusters. Landslides from cluster 3 with 31% of the landslides display medium to high ND for the assumed earthquake, and were found near ridges and farther away from rivers, suggesting seismic triggering. Cluster 2, with 12% of landslides closer to rivers, suggested climatic origins. Thus, while climate is a critical landslide contributing factor, seismic events may also contribute, either by predisposing to landslides or by reactivating them alongside climatic factors. These results enable the establishment of more precise and effective landslide mitigating measures considering mostly rainfall but also earthquakes as possible triggers.

The Degree of Capillary Absorption Reduction as a Parameter to Classify the Effectiveness of Secondary Horizontal Waterproofing

The dampness of the ground floors in buildings is generally a consequence of capillary rise of groundwater caused by the absence, damage or technical deterioration of the horizontal waterproofing of the masonry. Capillary absorption and damp transport are determined by the wetting properties of water relative to the material, as well as the structure and distribution of pores in the material. Chemical (injection) methods of secondary horizontal waterproofing are based on the technology of introducing injection liquid into the masonry section, which forms a lock which relies on the mechanism of capillary lumen constriction, hydrophilization, capillary sealing or a combined effect. A vital outcome of secondary horizontal waterproofing in a wall using the injection method is not only limited absorption but also its changed dynamics. The research paper describes the procedure leading to determining a criterion that allows to classify injection agents in terms of their impact on inhibiting capillary transport of damp in construction partitions.

Paleoenvironment and vegetational history of a Middle Pennsylvanian intramontane peat swamp: an example from the Lower Radnice Coal, Kladno coalfield (Czech Republic)

The depositional environment, hydrology and vegetational history of the Lower Radnice Coal (Duckmantian) in the Kladno coalfield was studied using sedimentary geology, coal petrology and paleobotanical/palynological methods. The peat accumulating wetland of the coal formed in a fluvial paleovalley approximately 15 km long and 2–5 km wide, bordered by basement paleohighs and landlocked in the interior of the central European Variscides. The peat swamp evolved on top of mud-dominated floodplain successions pedogenically modified to a vertic gleyed Protosol. Probably climatically controlled rising ground water table resulted in paludification that from downstream part gradually spread upstream. Most clastic load was deposited in the upper part of the valley, whereas only mud suspension was dispersed downstream throughout the vegetated swamp. The best conditions for peat accumulation were situated in the eastern part of the paleovalley, where up to 1.5 m thick coal with thin bands of impure coal and carbonaceous mudstone formed in an occasionally inundated rheotrophic system with peat accretion controlled by regional ground water table. The peat swamp was vegetated mainly by lepidodendrid lycopsids with Lepidodendron and Paralycopodites being dominant genera. Shrubby to ground cover vegetation was represented by medulosallean pteridosperms, small shrubby lycopsids, sphenopsids, and herbaceous ferns. Tree ferns were locally abundant, especially in mineral-rich substrates. The rheotrophic character of the peat swamp may indicate higher seasonality of the Variscan interior, compared to coastal areas in the North Variscan foreland with contemporaneous ombrotrophic peats. Modern equivalents of the Lower Radnice Coal swamp are inland planar tropical peat swamps in tributary paleovalleys of the Tasek Bera in peninsular Malaysia and central Congo basins.Graphical abstractLower Radnice Coal peat swamp.

Spatial analysis of thermal groundwater use based on optimal sizing and placement of well doublets

This paper proposes an approach to optimize the technical potential of thermal groundwater use by determining the optimal sizing and placement of extraction–injection well doublets. The approach quantifies the maximum technically achievable volume of extracted groundwater in a given area and, hence, the amount of heat exchanged with the aquifer, considering relevant regulatory and hydraulic constraints. The hydraulic constraints ensure acceptable drawdown and rise of groundwater in extraction and injection wells for sustainable use, respectively, prevention of internal hydraulic breakthroughs, and adequate spacing between neighboring doublets. Analytical expressions representing these constraints are integrated into a mixed-integer linear optimization framework allowing efficient application to relatively large areas. The applicability of the approach is demonstrated by a real case study in Munich, where the geothermal potential of each city block is optimized independently. Six optimization scenarios, differing in terms of required minimum installed doublet capacity and spacings between doublets, underline the adaptability of the approach. The approach provides a comprehensive and optimized potential assessment and can be readily applied to other geographic locations. This makes it a valuable tool for thermal groundwater management and spatial energy planning, such as the planning of fourth and fifth generation district heating systems.

MODELING OF GROUND WATER DYNAMICS AND ITS POLLUTION

Problem statement. Large accumulators of liquid waste (e.g., mine water ponds, tailing ponds, etc.) are long-term sources that change the hydrological regime. A negative consequence of this process is flooding of the territory. In addition, the infiltration of contaminated water from such hazardous sources changes the quality of groundwater. Therefore, it is important to analyze the impact of such anthropogenic sources on the process of flooding and deterioration of groundwater quality. To solve this problem, it is very important to use the method of mathematical modeling as an effective mean of researching problems of this class, since the use of physical modeling is practically impossible within the scope of problems of this class. The purpose of the article. Development of numerical models for predicting changes in the hydrological regime (flooding of the territory) and groundwater quality under the influence of anthropogenic pollution sources. Methodology. To assess the dynamics of changes in the hydrological regime, a two-dimensional equation of filtration of a non-pressure groundwater flow is used. A two-dimensional geomigration equation (planned model) is used to analyze changes in groundwater quality during infiltration of contaminated water from the settling pond. This equation takes into account the convective transfer of contaminants in the filtration flow, dispersion, and the intensity of contaminant infiltration into the groundwater flow. The method of total approximation is used for numerical integration of the filtration equation. For the numerical integration of the geomigration equation, an implicit splitting scheme is used. Scientific novelty. Effective numerical models for rapid assessment of changes in groundwater dynamics and quality under the influence of anthropogenic sources that change the hydrological regime are proposed. The constructed numerical models take into account a set of important physical factors that affect the process of geomigration and flooding of the territory, namely: filtration coefficient, variable depth of free-flowing groundwater, dispersion, intensity of the source of impurity emission into the groundwater flow. This makes it possible to obtain a comprehensive assessment of the process of flooding and groundwater pollution.. Practical significance. A computer code has been created that allows practical usage of the developed numerical models. This code is an effective tool for theoretical study of non-stationary processes of territory flooding and anthropogenic groundwater pollution. Conclusions. A numerical model for calculating groundwater dynamics has been developed. The model allows to predict the level of groundwater rise under the influence of a man-made source of wastewater infiltration from a settling pond. A numerical model for calculating the process of geomigration from an anthropogenic source of emissions has been developed. The model makes it possible to predict the dynamics of contamination zone formation in a non-pressure groundwater flow. The developed numerical models take into account the most important parameters that affect the formation of flooding zones and groundwater contamination.

Understanding the impact of climate-induced sea level rise on groundwater inundation in a low-lying coastal area: A numerical simulation in Southeast India

Global warming has led to rising sea levels, severely threatening coastal areas, particularly in low-elevation coastal zones. The groundwater in coastal aquifers of lower elevation is susceptible to groundwater inundation (GWI), an emerging hidden long-term hazard earlier to marine inundation. The inundation is mainly due to the hydraulic connection between sea level and shallow unconfined aquifers, resulting in groundwater upsurging towards the ground surface. To understand the potential impact of sea level rise (SLR) induced GWI on low-lying coasts, a transient state model was simulated and predicted in the Cuddalore regions of South India under 0.3 m, 0.6 m, and 1 m SLR scenarios. The simulation reveals that the aerial extent of groundwater rise (GWR) was 331.9 km2, 566.2 km2, and 650.8 km2 for 0.3 m, 0.6 m, and 1 m SLR scenarios, respectively. About 50% of the response was observed in the northern and central parts of the study area within a 5 km buffer, which is attributed to the deeper groundwater table. In contrast, the southern region exhibited a 10% decline in response due to shallow groundwater discharge to drainage, which dampened the shoaling effect. The present-day shallow groundwater tables in the southern region are more vulnerable to GWI from rising sea levels. Specifically, a 0.3 m SLR could inundate 14.9 km2. In comparison, a 1 m SLR could inundate 40.5 km2 of the area, including the Pichavaram mangrove forest, agricultural land, municipal structures, and the other regions that flooding could threaten. These inundations could have potential impacts, such as wetland loss, agricultural flooding, deteriorating water quality, and infrastructural damage. The present study provides valuable insights into the subsurface hydrodynamic and exposure impacts of sea rise-induced inundations. This can aid coastal engineers, policymakers, and decision-makers to plan appropriate mitigation measures.

A simplified calculation method for high-steep soil slope stability due to groundwater rise from irrigation

The groundwater is the critical factor impacting the stability of high-steep soil slopes (HsSS) on the loess tableland. In view of the shortcomings of the current commonly used calculation methods for HsSS, based on the Rankine earth pressure, the equilibrium conditions, and the strength failure criterion, a simplified calculation method for HsSS stability is proposed considering the typical characteristic that the failure surface of the high-steep slope is a double-segment line, and the critical groundwater level of the slope of the tableland edge was determined based on the HsSS stability model. The results are consistent with slope and modified the shortcomings of the existing model, such as the relatively concentrated and smaller of the stability coefficient. The critical groundwater level prediction model was applied to the Heifangtai tableland to verify the feasibility of the prediction model and point out the three high-risk points along the Heifangtai tableland.

What to Do When Septic Systems Are Impacted by Flooding from Storms or Groundwater Rise

The purpose of this publication is to explain how septic systems may be affected by floods from hurricanes and other storms and/or by climate change (sea-level rise) that raises the level of the groundwater under septic system soils. Written by Mary G. Lusk, and published by the UF/IFAS Department of Agricultural and Biological Engineering, November 2023.

Impact аssessment of the September 2022 disaster in the area of Karavelovo, Bogdan, and Slatina villages, Karlovo Municipality

On September 2nd, 2022, an intense and prolonged rainfall event caused severe flooding, landslides, debris flows, and groundwater rise, resulting in substantial damage, particularly in the northern slopes of Sredna Gora Mountain in Central Bulgaria. Various methodologies, including field analysis, remote sensing, and GIS tools, were employed to analyze the disaster’s causes and field conditions. Active sediment sources, deposition patterns, and mapping techniques were used to document the disaster’s impact. The results showed that the disaster resulted from the formation of numerous landslides, and rapid hydrological response led to riverine flooding, high-speed flows, and sediment deposition. An important contribution of this study is the generated landslide inventory map, that can be used for mountain road reconstruction and the planning of mitigation measures.

Effects of Irrigation Projects on the Classification of Yellow River Terrace Landslides and their Failure Modes: A Case Study of Heitai Terrace

The study of the classification and failure modes of Yellow River terrace landslides under the influence of irrigation projects is of key importance to alleviate the paradox between the rapid evolution of terrace landscapes caused by landslides and the survival of local residents. However, such studies remain controversial, despite it being widely recognized that a rise in groundwater level caused by irrigation is a key factor associated with landslide failure modes. In this paper, we take the Heitai terrace as a case study. Using aerial images and field investigations, we classify landslides in the Heitai loess layer into type A landslides (not related to groundwater) and type B1 and B2 landslides (related to groundwater). We analyze the failure modes and disaster-causing characteristics of each type of landslide, and our results indicate that the attenuation in soil strength is a key factor common to both type A and type B landslides, based on which type A landslides with small volume and short sliding distance are able to block the previous spring discharge, causing a rise in localized groundwater, which further contributes to type B landslides; the location of previous type B1 landslides with a large volume and long sliding distance and type A landslides may be more susceptible to type B2 landslides with a small volume and short sliding distance, where there are low confining pressures during the lower soil shear process. Therefore, we believe that the inevitable interaction effects between the failure modes of landslides during landslide evolution, which govern the geomorphological evolution of the Heitai terrace, are unavoidable. Combining these data with numerical analyses, we further demonstrate that a rise in groundwater level and discontinuous attenuation of soil strength caused by changes in soil properties during irrigation together control terrace landslides and their failure modes. From the results of interferometric synthetic aperture radar time-series monitoring of Yellow River terrace activity with and without irrigation projects, and electrical resistivity tomography groundwater detection, we conclude that in the future, Heitai terrace will continue to experience a high intensity of landslide activity, and conditions for the most catastrophic type of landslide (type B1) will remain, including the high localized groundwater caused by previous landslides, and the discontinuous attenuation of soil strength caused by the deterioration in soil properties. In this context, we believe that slope-cutting engineering will be one of the most economical means to achieve future landslide-type transformation on the Heitai terrace; this will mitigate the process of geomorphological evolution and improve the human living environment.

Study on the mechanism and rapid treatment method of leakage disease at the junction between the shaft and shield tunnel

Tunnel leakage disease will seriously affect the metro operation and threaten the safety of passengers. Therefore, this study investigates the mechanism of structural leakage disease at the junction between the shaft and shield tunnel through the operational tunnel in the Beijing area. Firstly, the characteristics and intrinsic cause of the leakage are analyzed by ground penetrating radar, endoscope detection, and total station. The field inspection indicates that the water-rich cavity caused by the rise of groundwater is the main external environmental factor inducing structural leakage. The uneven deformation of the junction between the shield segments and ring beam and the deterioration of the ring beam structure are the main reasons for the waterproof layer failure, which further lead to structural leakage. In addition, numerical simulations are carried out to study the leakage mechanism of the junction structure under the effects of structural uneven deformation and ring beam deterioration. The numerical results show that the leakage caused by uneven deformation of tunnel junction is significant. Especially, the water-rich cavity near the ring beam will aggravate structural leakage. Furthermore, the deterioration of the ring beam structure has a more significant effect on the structural leakage, and the leakage mainly occurs in the ring beam and ring beam-segment joints. This finding is basically consistent with the actual leakage situation. In addition, the rapid treatment method for plugging water-rich cavities and structural defects is proposed, and a new cement-based material with good non-dispersible underwater properties is developed. The surface observation and internal detection show that the rapid treatment method effectively controls structural leakage. This research can provide a reference for future similar leakage and disease control projects of metro subways in operation.

Rising Coastal Groundwater as a Result of Sea‐Level Rise Will Influence Contaminated Coastal Sites and Underground Infrastructure

AbstractSea‐level rise (SLR) will cause coastal groundwater to rise in many coastal urban environments. Inundation of contaminated soils by groundwater rise (GWR) will alter the physical, biological, and geochemical conditions that influence the fate and transport of existing contaminants. These transformed products can be more toxic and/or more mobile under future conditions driven by SLR and GWR. We reviewed the vulnerability of contaminated sites to GWR in a US national database and in a case comparison with the San Francisco Bay region to estimate the risk of rising groundwater to human and ecosystem health. The results show that 326 sites in the US Superfund program may be vulnerable to changes in groundwater depth or flow direction as a result of SLR, representing 18.1 million hectares of contaminated land. In the San Francisco Bay Area, we found that GWR is predicted to impact twice as much land area as inundation from SLR, and 5,282 additional state‐managed sites of contamination may be vulnerable to inundation from GWR in a 1.0 m SLR scenario. Increases of only a few centimeters of elevation can mobilize soil contaminants, alter flow directions in a heterogeneous urban environment with underground pipes and utility trenches, and result in new exposure pathways. Pumping for flood protection will elevate the saltwater interface, changing groundwater salinity and mobilizing metals in soil. Socially vulnerable communities are disproportionately exposed to this risk at both the national scale and in a regional comparison with the San Francisco Bay Area.