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Leakage-induced soil erosion poses a major threat to dike failure, particularly during floods. Timely detection and notification of leakage outlets to dike management are crucial for ensuring dike safety. However, manual inspection, the current main approach for identifying leakage outlets, is costly, inefficient, and lacks spatial coverage. To achieve efficient and automatic localization of dike leakage outlets, an innovative strategy combining drones, infrared thermography, and deep learning is presented. Drones are employed for dikes' surface sensing. Real-time images from these drones are sent to a server where well-trained detectors are deployed. Once a leakage outlet is detected, alarming information is remotely sent to dike managers. To realize this strategy, 4 thermal imagers were employed to image leaking outlets of several models and actual dikes. 9,231 hand-labeled thermal images with 13,387 leaking objects were selected for analysis. 19 detectors were trained using transfer learning. The best detector achieved a mean average precision of 95.8 % on the challenging test set. A full-scale embankment was constructed for leakage outlet detection tests. Various field tests confirmed the efficiency of the proposed leakage outlet localization method. In some tough conditions, the trained detector also evidently outperformed manual judgement. Results indicate that under typical circumstances, the localization error of the proposed method is within 5 m, demonstrating its practical reliability. Finally, the influencing factors and limits of the suggested strategy are thoroughly examined. [ABSTRACT FROM AUTHOR]

This paper presents a laboratory study to investigate the wave overtopping over dike on the fringing reef with a large steep fore-reef slope. The experimented models were set up in wave flume, considering three different slopes of dike combined with various wave and still water levels and different roughness cases. The research results indicate that wave overtopping over a dike on the fringing reef depends not only on the relative crest freeboard but also on a synthetic parameter typical for the wave hydrodynamic properties of the fringing reef characteristics and the slope of the dike. An empirical equation of wave overtopping discharge for dike on the fringing reef was derived based on an equation in EurOtop2018 by adding new synthetic parameter, and the comparison of the data from the new empirical formulas with the measured data showed good agreement. The proposed equation of this paper has been applied to estimate wave overtopping discharge over dike on the fringing reef having a large steep fore-reef slope.

The basic purpose of the present research is to numerically elucidate the flow around a single dike in four different geometric configurations (CN: no cylinders, C5: 5 cylinders, C10: 10 cylinders, C15: 15 cylinders), under conditions of a constant flow rate and subcritical flow. This involved substituting the impermeable dike with varying numbers of piles to validate the observed experimental flow patterns, particularly the conditions leading to reverse flow formation. OpenFOAM, an open-source algorithm, was utilized for the simulation, incorporating the volume of fluid (VOF) method. Accurately depicting the reverse flow formation with minimal numerical diffusion, a strategy involving multizone meshing and the application of mesh refinement zones was utilized. These refinements were particularly focused on the section between 1.8 m and 2.2 m within the numerical domain. The water surface profile in front section of the dike and the averaged velocity at five different locations, which were then compared with the numerical results. The numerically predicted streamwise velocity showed a percentage error ranging between 0.5% and 4.5%. The numerical results from this study are pivotal in dike design, aiming to mitigate accelerated wear during flood events and to protect both the dike head and the adjacent bank from high energy flow failures. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, Erbil has faced an elevated risk of floods due to climate change and incorrect land development design and management. To tackle this issue, this study uses Hydrologic Engineering Center River Analysis System (HEC-RAS) software to address flood inundation and reduction by constructing dikes. This involved using a digital elevation model (DEM) in the study area (Mass Village) east of Erbil. The study delineated the catchment area and employed watershed modelling system (WMS) software. Furthermore, Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) software was used to create a flood hydrograph, which the HEC-RAS software used to estimate flood inundation areas, velocity, and water levels. The study identified water surface areas and velocities prone to flooding in the urbanised area, with water depths ranging from 0 to 5 m. The model was rerun after the construction of the dikes, resulting in water depths ranging from 0 to 7.2 m upstream of the dikes. The modelling results indicated a water depth of 0 m downstream of the dike (protected area), demonstrating that the dike's construction successfully reduced flooding in the urbanised area.

Abstract The temporal evolution of dike volume can help elucidate its propagation dynamics, however, such an estimation is possible only when there are geodetic observations available along the dike path. Here it is shown that dike volume history during eight eruptions can be reconstructed from seismic moment release using high resolution earthquake catalogs. The critical volume needed for each dike to reach the surface is simulated and compared to the accumulated volume prior to eruption in order to infer fracture toughness, a measure of resistance to fracture. It is found that fracture toughness varies between 123–833 MPa m 1/2, with larger values corresponding to longer dikes. Resistance to fracture dominates over viscous dissipation when the dikes propagate through unfractured heterogeneous material with large rigidity contrast, or when there is dike segmentation. These results can be utilized for real time monitoring of dike growth, forecasting eruption volume, and for constraining analog or numerical models of dike propagation.

This article revisits an ostensibly important monument in Classical Attic historiography: the so-called Tomb of Critias, as preserved in a scholium note in Aeschines' "Against Timarchus" (1.39). We survey prior scholarly positions on the realia of this monument, suggest it is a fiction, and consider the possible sources for the hexameter verse associated with it. We argue that the poetic composition from which the entire tradition derives, rather than being an inscription on a tomb, may in fact be an oligarchic commemoration, perhaps an encomium or epitaphios logos recited at Eleusis in the aftermath of the fall of the Thirty. As such, the verse composition may allude to a historiographical tradition that viewed the Thirty as a subversive hetaireia/kōmos group led out to govern the unruly dēmos. The reception of this composition generates a 'lieu de mémoire' in the historical imagination of later readers. The composition offers a piece of comparanda for the political views expressed by other Athenians with pro-oligarchic tendencies, an extreme formulation that strongly contrasts with the extant writings of Critias, Plato, and Xenophon. In revisiting this short anecdote we highlight the relevance of both scholia and monuments in our understanding of Attic historiography. [ABSTRACT FROM AUTHOR]

Geotextiles, as a type of common filtration material, have broad prospects in emergency rescue of dike backward erosion piping (BEP). To investigate the filtration performance of geotextile in BEP emergency rescue, several experiments were conducted using nonwoven and woven geotextiles to simulate the process of rescuing BEP with geotextiles. The influence of geotextile specifications and types on hydraulic compatibility of the filter system was analyzed, and the clogging mechanism of geotextile during dealing with BEP was revealed at a microscopic level. The results showed that the nonwoven geotextile filter with an equivalent pore size of 0.103 mm had a gradient ratio value of less than 3, and it had a highest flow rate of 260 mL/min. Increasing the thickness and pore size of nonwoven geotextiles within a certain range helped enhance their anti-clogging ability. The main mechanism of clogging in nonwoven geotextiles was the deposition of fine sand particles on their surface, forming a layer of low permeability soil. Plain woven geotextiles experienced severe clogging with a 42% reduction in flow rate, and it was not suitable for rescuing BEP. The clogging mechanism of woven geotextile involved the blocking of horizontal water passages by fine sand particles. [ABSTRACT FROM AUTHOR]

Multiple Pool Fire (MPF) reasonably enhances the flame height, the rate of fuel combustion and irradiation due to cascading effect and flame merging of multiple pools. The distribution of temperature and radiative heat flux from the source is the key parameter in predicting safety distance. The current study's major objective is to develop a Computational Fluid Dynamics (CFD) model to calculate the safety distance of MPF and validate the predicted results (flame temperature, radiative heat flux, CO2 and O2 mass fraction) with the experimental data. The flame structure and its thermal properties have been evaluated using the Reynolds Averaged Navier Stokes (RANS) and the Large Eddy Simulation (LES) model. The CFD results are found to be in close agreement with the experimental findings. The LES turbulence model predicts more accurately the flame structures and the fluctuations with an error of less than 3%, while the Re-Normalization Group k-ε model predicts the average characteristics. This authenticates the accuracy of computational methodology and robustness of the LES turbulence model to predict MPF flame characteristics. Furthermore, this computational methodology can be utilised by the industries for quantitative risk assessment and the worst-case scenario of various pool fires to save the human and material of the workplace beforehand. [ABSTRACT FROM AUTHOR]

The Lower Oligocene basic dikes are cropped out in the Chah-e-Alikhan area (Northeast of Isfahan province, North of the Daq-e-Sorkh desert). These dikes show NE-SW and NW-SE trends and cross cut the Eocene volcanic rocks and associated flysches. NW-SE dikes are younger and cut the NE-SW ones. These dikes are similar in petrography and are composed of plagioclase, clinopyroxene, olivine, sanidine, Cr-spinel and ilmenite. Zeolite, serpentine, calcite and magnetite are secondary minerals. These dikes represent the porphyritic, glomeroporphyritic, poikilitic and trachytic textures. Intergranular and granular textures can be seen at the center of the larger dikes. These basalts are enriched in alkalis (Na2O+K2O), LREE and LILE (Cs, Rb, Ba, Pb) and have high values of LREE/HREE ratio (La/Yb=8.9-10). In the classification diagrams, which are based on the incompatible elements and HFSEs, they are classified as alkali basalts. The primitive magma of these basaltic dikes has been produced by partial melting of a garnet-spinel lherzolite of the mantle previously suffered the carbonate metasomatism. The formation of the alkali basalt dikes of the Chah-e-Alikhan area can be ascribed to the former subduction of the Central- East Iranian Microcontinent (CEIM) confining oceanic crust and decompression melting induced by the extensional basin of the Anarak‒Jandaq area in Early Oligocene. The primary basaltic magma has been formed by low degree of partial melting of a metasomatised mantle lherzolite during continental crust extension episode in the lower Oligocene and has been ascent through the faults. Introduction In the Northwest of CEIM (Central-East Iranian Microcontinent), along the Great Kavir fault, volumes of alkali basalts with the lower Oligocene age are outcropped as volcanic and subvolcanic (Dike) rocks. In this research, the subvolcanic exposures of this basic magmatism in the the Chah-e-Alikhan area is discussed. The Lower Oligocene basic dikes are cropped out in the Chah-e-Alikhan area (Northeast of Isfahan, Northeast of Zavareh, and Northwest of the CEIM). These dikes show NE-SW and NW-SE trends and cross cut the Eocene volcanic rocks and associated flysches. In this paper, the geological and petrological aspects, as well as the geodynamic setting of alkali basalt dikes of the Chah-e-Alikhan area are discussed. Study of these dikes, as a part of the Cenozoic alkaline magmatism from Northwest of the CEIM, will be useful in understanding the geodynamical evolution of the Central Iran. Analytical method The method of study is including petrography (field, library and microscopic studies) and whole rocks geochemical analysis of rocks. 13 fresh whole rock samples of alkali basalts from the Chah-e-Alikhan area were selected for the major and trace elements chemical analyses. Whole rock geochemical analyses carried out by using a Bruker S4 Pioneer XRF at the Central Laboratory of the University of Isfahan. Trace element compositions of the selected samples were achieved by ICP-MS (Inductively coupled plasma-mass spectrometry) at the Zarazma Mineral Studies Company (Tehran, Iran). Results and discussion The rock-forming minerals of the Chahe-e-Alikhan basic dikes are Cr-spinel, olivine, clinopyroxene, plagioclase, sanidine and ilmenite. Zeolite, serpentine, calcite and magnetite are secondary minerals which are formed as a result of the alteration of primary minerals. Petrographical characteristics indicate that these dikes are alkali basalt and represent the porphyritic, glomeroporphyritic and trachytic textures. Intergranular and granular textures can be seen at the center of the larger dikes. These basalts are enriched in alkalis (Na2O+K2O=4.5-5.4 wt%), LILEs (Cs, Rb, Ba, Pb) and have high values of LREE/HREE ratio (La/Yb=8.9-10). Trace elements ratio diagrams such as La/Nb versus La/Yb, Dy/Yb against La/Yb, Sm/Yb versus La/Yb (Bogaard and Worner, 2003) and Ce/Yb-Ce (Ellam, 1992) are used in order to determination of the depth, type and degree of partial melting of the source rock. Based on the geochemical characteristics and diagrams, the primitive magma of the Chah-e-Alikhan alkali basalts possibly have been produced by about 5 to 10 percent partial melting of a garnet-spinel lherzolite, which is located at the depth of about 105 km, as a part of a mixed asthenospheric–lithospheric mantle. The elevated values of the Zr/Hf ratio and the Na2O + K2O versus TiO2 diagram (Zeng et al., 2010) indicate that the primitive magma of the studied basic dikes previously suffered the carbonate metasomatism. The Chah-e-Alikhan alkali basalts show high values of the Alkalis (Na2O + K2O), enrichment in LREE, HFSE and LILE. The subducted oceanic slab is the source of carbon and LILEs are the mobile components of subduction (Shaw et al., 2003). Considering that Cs is a highly fluid mobile element, enrichment in Cs relative to Rb suggests that the fluid phases derived from a subducting slab are probably the metasomatic agents. The lower Oligocene alkaline magmatism in the Chah-e-Alikhan area and the enrichment of the mantle with incompatible elements (metasomatism) can be attributed to two oceanic crust subduction events: (1) Northeast ward Neotethys subduction along the Zagros Thrust Zone beneath the Central Iran from the Triassic to the Eocene (Torabi, 2010); and (2) Subduction of an oceanic crust along the Great Kavir Fault, which is situated to the western margin of the CEIM. The spreading of the last ocean crust started in the Triassic and ended in the Eocene. The remnants of this oceanic crust are found as ophiolitic melanges on the western side of the CEIM, such as the Nain, Surk, and Ashin ophiolites (Rajabi and Torabi, 2012; Torabi, 2010). The geological history and position of the Chah-e-Alikhan alkali basalt dikes suggests that the the carbonate metasomatism of the mantle peridotites can be attributed to the subduction of the CEIM confining oceanic crust. Several tectonic discrimination diagrams have been used for determination of the tectonic setting of the Chah-e-Alikhan basalts. The La/Yb versus Th/Nb (Hollocher et al., 2012), Ta/Yb against Th/Yb (Gorton and Schandl, 2000) and DF1 versus DF2 (Verma and Agrawual, 2011) diagrams suggest a within-plate (continental) tectonic setting. The activity of the major faults of the area such as Great Kavir, Chah Mishury and Chah Gireh Faults has been created a suitable inter-plate extensional system to ascending the Lower Oligocene alkali basalt magma in the Chah-e-Alikhan area. Conclusion The Lower Oligocene alkali basalts of the Chah-e-Alikhan area is a part of the intra-continental alkaline magmatism crosscuts the Eocene volcanic rocks. The area provides a setting to study the Cenozoic alkaline magmatism of the northwest of the CEIM. These basalts are enriched in total Alkalis, TiO2, LREE and LILEs. They have been produced by about 5 to 10 percent degree of partial melting of a garnet-spinel bearing lherzolite of a mixed lithospheric-asthenospheric mantle which is previously metasomatised. The mantle enrichment can be ascribed to the subduction of the CEIM confining oceanic crust beneath the Central Iran from the Triassic to the Eocene. The Grate Kavir Fault and related faults have played an important role in the Lower Oligocene alkaline magmatism in northwest of the CEIM.

Dike foundation piping is one of the most important reasons for the dangerous situation and even the breach of dikes in Poyang Lake Area. It is of great significance to study and explain the disaster-causing mechanism of dike foundation piping in Poyang Lake Area from the mechanism so as to deal with the dangerous situation of piping and carry out emergency rescue scientifically.In this paper, an organic glass model tank is designed and manufactured, which integrates the functions of pore water pressure signal acquisition, seepage flow observation, erosion soil particle collection, graded constant head control, internal water circulation and so on. Based on the typical dike foundation structure of a dike in Poyang Lake Area, the physical model test of piping is carried out by using the prototype soil of dike foundation, and the whole process of piping occurrence, development and collapse of prototype multi-layer complex dike foundation is completely simulated. Combined with the experimental phenomena, the hydraulic conditions and soil particle erosion rate of the six stages (surface crack development stage, latent layer failure stage, overlying layer failure stage, piping channel upstream stage, embankment foundation failure stage, embankment foundation collapse stage ) in the process of piping occurrence and development are analyzed, and the special embankment foundation failure mechanism of the dike is explained by analyzing the effect of vertical seepage force.The results show that the piping failure in the dike foundation structure in Poyang Lake Area is concentrated in the underlying sand layer. Under the action of osmotic pressure, the overlying weak permeable layer is penetrated by seepage, and the piping channel is formed on the contact surface between the sand layer and the overlying layer, which accelerates the erosion of soil particles and eventually leads to the dike foundation collapse. The loam layer sandwiched in the clay layer in the embankment foundation of a typical dike in the Poyang Lake Area cannot play the role of the transition layer between the strong and weak permeable layers. The law of soil particle erosion is similar to that of the embankment foundation without the transition layer. The growth rate of the cumulative erosion of the soil particles forming the surface piping outlet and the embankment foundation cracking is less than 0.1 g/s; the average overall critical horizontal gradient of the dike foundation where piping occurs is about 0.1. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally the changing of a hydraulic characteristic of combined hydraulic structure owing to the existence of dike structure. Different models of combined structures are used with rectangular gates and rectangular weirs, respectively. Also, the location of the dike structure is considered. A dike is located upstream, downstream, and on both sides of the combined hydraulic structure. Discharge quantity, average downstream water depth, discharge coefficient, and Reynolds number are adopted to describe the alteration in hydraulic behavior of a combined structure. While the relation between upstream Froude number and downstream Froude number, as well as the relation between downstream Froude number with distance, are employed to illustrate the interactive response between dike and combined structure, From the study, the relation between Froude number at downstream and non-dimensional downstream distance as well as the relation between non-dimensional downstream water depth and non-dimensional distance reveal how the dike location effects on water depth and flow velocity, which lead to a change in the type of flow. Here, the dike position is shared in the form of a hydraulic jump at downstream of the combined structure. The experimental data were statistically analyzed to ensure their validity and reliability. The importance of this study is concentrated on how the location of the dike structure is shared in the alteration in the hydraulic characteristics of the combined hydraulic structure, especially the rise in the water depth at downstream, in addition to the change in the hydraulic jump height and energy losses. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Prevention of river or coastal dikes from erosion failure has become more important than ever due to the increasing impact of climate change. A microbially induced carbonate precipitation-based approach was investigated as a possible more sustainable solution for sandy dikes erosion due to overtopping. A series of model tests in a hydraulic flume were carried out on biotreated sand dike models. The models were treated using either surface spray or percolation method and then subjected to flow under various flow rates ranging from 2 to 22 L/s. The erosion, stability, geotechnical parameters, and the amount of calcium carbonate precipitated in the models were measured to assess the effect of the biotreatment. The testing results showed that the untreated sandy dike can be eroded easily, while no erosion occurred after the biocementation using five treatments of 1.5 M of cementation solution through either percolation or surface spray method. Data suggest that in almost the equivalent calcium carbonate content, the percolation method allows soil in a relatively deeper layer to be treated, while the changes occurred just on the formed crust of the models treated with the surface spray method. [ABSTRACT FROM AUTHOR]

AbstractStorm surge-induced flooding (SSIF) is a major hazard for coastal areas under intensified typhoons. Therefore, it is essential to assess the potential impacts of SSIF (SSPIA). This study proposes a multidisciplinary framework for refined SSPIA using an ocean model and a refined exposure estimation method. First, a finite-volume coastal ocean model (FVCOM) and a typhoon model were developed and validated. Then, five scenarios of varying intensity were defined and combined with FVCOM to identify inundation scenarios. Subsequently, machine learning was used to obtain the fine-scale gridded population and gross domestic product (GDP) maps based on the census and geospatial data. Finally, we assessed the magnitude of the affected population and GDP based on the inundation scenarios and refined exposure datasets. We selected Zhoushan Island as a study area to implement this framework. Our assessment results show that the lowest scenario (955 hPa) affected 2587 people and 323.745 million CNY of GDP, while the highest scenario (915 hPa) affected 259,516 people and 20,178.898 million CNY of GDP. Therefore, it is imperative to implement effective mitigation and adaptation measures to address the threat of SSIF. This framework will apply to all flood-prone areas for a refined assessment of the potential impacts of SSIF.

The Fagradalsfjall eruption commenced on 19 March 2021 on a ~180-m-long eruptive fissure, following a 23-day dike intrusion. New eruptive fissures opened northeast of the initial eruption site on 5, 6–7, 10, and 13 April 2021. The northernmost eruption occurred on 5 April, approximately 1 km northeast of the initial fissure, with the other fissure openings between this and the initial eruptive vents. Still images from web cameras and time-lapse cameras are available for five of the fissure openings. These data show that the eruptions were preceded by steam emitted from cracks in the exact locations where the eruptions started. The time between the first steam observations and the visual appearance of glowing lava ranged between 15 s and 1.5 min during night observations and from 9 to 23 min during daytime observations. The difference in observation time is likely explained by the different lighting conditions. The eruptive vents are located where the north-easterly oriented dike intersected pre-existing north-south-oriented fractures, inferred to be strike-slip faults. These fractures could be identified on a high-resolution ICEYE interferogram as well as on pre-existing aerial photographs and digital elevation models. This interferogram spanned the first day of the eruption (19–20 March 2021). It not only displays deformation related to the pre-eruptive dike intrusion but also shows lineations in locations where eruptive vent openings occurred later in April 2021. These findings demonstrate how Interferometric Synthetic Aperture Radar Analysis (InSAR) can be used to forecast likely locations of subsequent eruptive vent openings, which is of great importance for hazard assessment and defining exclusion zones during fissure eruptions. [ABSTRACT FROM AUTHOR]

The Lower Oligocene basic dikes are cropped out in the Chah-e-Alikhan area (Northeast of Isfahan province, North of the Daq-e-Sorkh desert). These dikes show NE-SW and NW-SE trends and cross cut the Eocene volcanic rocks and associated flysches. NW-SE dikes are younger and cut the NE-SW ones. These dikes are similar in petrography and are composed of plagioclase, clinopyroxene, olivine, sanidine, Cr-spinel and ilmenite. Zeolite, serpentine, calcite and magnetite are secondary minerals. These dikes represent the porphyritic, glomeroporphyritic, poikilitic and trachytic textures. Intergranular and granular textures can be seen at the center of the larger dikes. These basalts are enriched in alkalis (Na2O+K2O), LREE and LILE (Cs, Rb, Ba, Pb) and have high values of LREE/HREE ratio (La/Yb=8.9-10). In the classification diagrams, which are based on the incompatible elements and HFSEs, they are classified as alkali basalts. The primitive magma of these basaltic dikes has been produced by partial melting of a garnet-spinel lherzolite of the mantle previously suffered the carbonate metasomatism. The formation of the alkali basalt dikes of the Chah-e)Alikhan area can be ascribed to the former subduction of the Central-East Iranian Microcontinent (CEIM) confining oceanic crust and decompression melting induced by the extensional basin of the Anarak‒ Jandaq area in Early Oligocene. The primary basaltic magma has been formed by low degree of partial melting of a metasomatised mantle lherzolite during continental crust extension episode in the lower Oligocene and has been ascent through the faults. [ABSTRACT FROM AUTHOR]

Frequent drought and worsening salinity intrusion challenge future land uses and livelihoods in the Vietnamese Mekong Delta. The central government is, therefore, formulating a new strategy premised on adaption to natural environmental dynamics. For an achievable strategy that bridges the gap between plans and practice, it is important to understand what drives land-use changes at the farm level. Previous research developed and applied a multi-scale drivers framework in the highly flooded zone of the delta. The current study uses that same framework to investigate the land-use history and drivers of change in the salinity intrusion zone of this delta from 1975 to 2016. We interviewed 32 farmers in Tra Vinh Province and used transcript analysis to quantify the influence of the drivers that the farmers mentioned. We then compared the drivers of land-use change with those found earlier in the highly flooded zone. Results show more diversification of land uses and land-use changes in the salinity intrusion zone. Farmers here followed three main pathways: rice intensification, integrated farming of rice and vegetables/aquaculture, or intensive shrimp farming. Land-use changes were conditional on the regional infrastructure construction to preserve freshwater conditions. However, household-scale drivers, especially natural and financial assets, were most frequently mentioned. Socio-economic context also emerged as an important driver, particularly trends and pressures from the community and markets. [ABSTRACT FROM AUTHOR]

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Volcanic eruptions are often preceded by episodes of in ation and emplacement of magma along tensile fractures. Here we study the 2021 Tajogaite-Cumbre Vieja eruption on La Palma, Canary Islands, and present evidence for tensile fractures dissecting the new cone during the terminal stage of the eruption. We use synthetic aperture radar (SAR) observations, together with drone images and time-lapse camera data, to determine the timing, scale and complexities associated with a fracturing event, which is diverging at a topographic ridge. By comparing the field dataset with analogue models, we further explore the details of lens-shaped fractures that are characteristic for faults diverging at topographic highs and converging at topographic lows. The observations made at Cumbre Vieja and in our models are transferrable to other volcanoes and add further evidence that topography is substantially affecting the geometry and complexity of fractures and magma pathways, and the locations of eruptions.

Diked and drained coastal lowlands rely on hydraulic and protective infrastructure that may not function as designed in areas with relative sea-level rise. The slow and incremental loss of the hydraulic conditions required for a well-drained system make it difficult to identify if and when the flow structures no longer discharge enough water, especially in tidal settings where two-way flows occur through the dike. We developed and applied a hydraulic mass-balance model to quantify how water levels in the diked and tidally restricted coastal wetlands and water bodies dynamically respond to sea-level rise, specifically applied to the Herring River Estuary in MA, USA, from 2020 to 2100. Sensitivity testing of the model parameters indicated that primary outcomes were not sensitive to many of the chosen input values, though the terrestrial water input rate to the estuary and the flow coefficient for the hydraulic infrastructure were important. The relative importance of parameters, however, is expected to be site specific. We introduced a drainability metric that quantifies the net water volume drained over every tidal cycle to monitor and forecast how rising water levels on either side of the dike affected the net draining or impounding conditions of the system. Ensembles of model results across parameter and sea-level scenario uncertainties indicated that substantial impoundment of the Herring River Estuary was expected within ~ 20 years with the existing flow structures, a sluice and two flap gates. Simulations with up to three additional gates did not dampen this trend toward impoundment, suggesting that rising impounded water levels are likely even with major construction upgrades. Increasingly impounded diked coastal waterbodies present a hydrologic challenge with socioecological implications due to projected flooding and ecosystem impacts. Solutions to this challenge may be to allow coastal wetland restoration pathways or require substantial and recurring infrastructure improvement projects. [ABSTRACT FROM AUTHOR]

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The Koshi, one of the biggest tributaries of the Ganges River, has been renowned for centuries for its erratic behaviour and destructive flooding of the Indo-Nepalese plain. Based on the Tennessee Valley Authority model’s success and in order to develop the region, the river was totally dammed in 1959, radically transforming the way local communities relate to water in the wetlands of the Koshi plain. Since then, embankments have been built extensively in this plain both in India and Nepal. Devastating incidents, such as the spectacular disaster in 2008, are still vivid in inhabitants’ memories. Despite a questioning of the himalayan region’s management paradigm, the model continues to be applied extensively, with gradual development having recently been achieved in Nepal on secondary rivers in the Tarai plain. This article sets out to analyse the impact of this programme of embanking Koshi affluents in the villages of Tilathi and Narsingh, on the right and the left banks of the Koshi respectively. It shows that in recent decades, floods have become more frequent, often prolonging water removal time, and that the causes of floods are multiplying. These two case studies are emblematic of a demonstration of how floods are transformed into socio-environmental disasters and are vital for studying the structural dimensions of who wins and who loses in this new water-balance configuration where areas are exposed or protected.

This study aimed to assess the suitability of lime treatment for use in dikes in the Netherlands. The effect of this technique on the behavior of a Dutch clay was addressed by comparing the detailed response of lime-treated and natural samples at different lime contents (1.25% and 2.25%) and curing periods. A series of laboratory tests consisting of index classification, constant rate of strain, and triaxial and hole erosion tests were performed. The results demonstrated that lime treatment altered the soil response. Differences were observed in the physical, compressibility, strength, and erodibility properties. It was found that lime improved considerably the resistance to compression and erosion, but the effect on hydraulic conductivity was limited. The triaxial test results showed that lime treatment was particularly effective at low stress (<25 kPa) and low strain levels (<10%). During shearing, lime-treated samples exhibited dilative tendencies and enhanced effective strength properties until a stress-strain state was reached that was believed to be related to the breakage of the bonding structure of the sample. The findings of this study demonstrate that the merits of lime treatment can be of particular benefit in dike applications, particularly when the focus is on improving soil erosion resistance. [ABSTRACT FROM AUTHOR]

Leaks refer to seepage holes running through a dike body or foundation, the formation of which may pose dire threats to dike safety and cause dike breaching due to a large flow rate and strong scouring force. Once the water inlet of a leak is detected, sealing and rescue measures should be taken in accordance with the principle of "inlet plugging and outlet anti-filtration". The key is the quick filling and stability of the plugging materials. Herein, the rescue technology of dike leaks is systematically laid out; the formation causes and development mechanism of the leaks are analyzed; the dike leak detection, plugging, and sealing technology is summarized; and the future research direction is clarified. Existing plugging technology and equipment are complicated and time-consuming. Hence, plugging methods should be innovated and improved to effectively improve the efficiency and success rate of emergency rescues. A new concept of "grade-by-grade plugging and sealing" is correspondingly proposed for dike leaks, changing leak rescues from "single-level plugging and sealing at the leak inlet" to "grade-by-grade plugging and sealing at the portal and inside the leak". A tandem closed space is formed in the leak. The hydrodynamic pressure is changed from the independent bearing of the portal to the gradual bearing of the plugging materials at the portal and inside the leak. [ABSTRACT FROM AUTHOR]

The Nanggulan Formation sediments form a weakly undulating hill and range in age from the Middle Eocene to the Late Oligocene. In Samigaluh and Sermo areas, a series of sedimentary rocks with small dimensions resembling fragments and forming a steep hilly morphology is exposed. Outcrops are mainly made up of sandstone and claystone interbedded with lignite intercalation. An outcrop in Sermo-2 found andesite intruding claystone. Claystone is found near rock contact, where it is an alteration to metasediment and chlorite is formed. Petrographic data showed the presence of chlorite, pyrite, and kaolinite. Andesite dike is one factor that contributes to the Nanggulan Formation being exposed to the surface. The Nanggulan Formation is a roof pendant above a dike. The implications of the roof pendant are related to the propylitic to argillic of hydrothermal alteration, which produce chlorite, pyrite, illite, and kaolinite minerals.

O objetivo é analisar a tensão entre duas formas díke na tragédia de Sófocles Édipo rei. Como as tragédias ocupavam um papel privilegiado na pólis, as encenações constituíam uma instituição política. Devido a isso, as tragédias representavam certos conflitos sociais e políticos entre uma tradição arcaica e uma nova ordem democrática, tensões estas que podem ser evidenciadas na investigação promovida por Édipo. Neste inquérito há um conflito entre duas formas de justiça, uma divina (tradicional) e outra humana (democrática e institucional). O artigo, primeiramente, descreve a relação entre tragédia e pólis; em seguida, assinala o conflito que se desenhava na pólis democrática e que se refletia, de certo modo, nas peças trágicas; por fim, examina, em Édipo rei, a articulação antagônica entre a díke tradicional e a humana.

The marshes and coastal areas of the river Dives, Calvados (France), are threatened both by water and sea level rises, coastal floodings and submersions as consequences of the global and local climate changes. The river Dives crosses this dyked marshland which covers nearly 10000 ha and whose impoldering dates since the 12th century. Local stakeholders are much concerned by the global decay of the dikes and wish to benefit from the expertise of a national research program (National Research Agency 2019-2023 DIGUES for Dikes, Interactions, Management, Uses, Environment and Scenario) in order to identify potential adaptation strategies. This exploratory research program aims at identifying natural and man-made habitats that cover the dikes and giving a better understanding of the evolutionary processes of this at-risk territory. The use of drone surveys and of a transect method over the landscape help determine disturbing elements that could have an impact on these flood protection structures. In addition to this alternative approach of habitat monitoring, this research gives the opportunity to establish different trend scenarios for the dikes of the river Dives that represent a central challenge in climate change issues.

Since the rapid economic development within the dike is inconsistent with the level of flood control management,dike break is prone to occur under over-standard floods and causes serious losses of life,economy,and ecological environments.Taking a key dike in the Poyang Lake area as an example,this paper proposed a dike-break-induced flood evolution simulation method based on hydrodynamics.The proposed method adopted the MIKE 21 software for dike-break-induced flood evolution analysis.The roughness of the underlying surface was determined reasonably according to different types of land use.Meanwhile,quantitative evaluation models of life,economic,and environmental losses that had clear physical meaning were established in the Python platform.The research results can provide references for flood warning and risk management and control of flood disasters in protected areas.

Normal stress on dikes is one of the most critical parameters for a sound dike design. With more rapidly rising sea levels due to global warming, dikes are seriously threatened by overtopping induced by the combination of wave and storm surge. Compared with wave overtopping on positive freeboard, the curling breaking wave on dikes induced by the combined wave and surge overtopping may destroy the weakly protected dike crest and landward slope. Thus, in order to prevent severe damage to dikes, it is necessary to fully understand the normal stress induced by the combined wave and surge overtopping. In this paper, physical model tests were carried out to study the normal stress on dike induced by the combined wave and surge overtopping. Two characteristics of normal stress on dike were observed. The spatial distribution of normal stress on dike was also analyzed. It was found that the Weibull distribution can be used to effectively describe the statistical distribution of peak normal stresses. Furthermore, by curve fitting of the laboratory measured data, the Weibull factors on the part of the crest and the upper part of the landward slope were obtained.

Frequent drought and worsening salinity intrusion challenge future land uses and livelihoods in the Vietnamese Mekong Delta. The central government is, therefore, formulating a new strategy premised on adaption to natural environmental dynamics. For an achievable strategy that bridges the gap between plans and practice, it is important to understand what drives land-use changes at the farm level. Previous research developed and applied a multi-scale drivers framework in the highly flooded zone of the delta. The current study uses that same framework to investigate the land-use history and drivers of change in the salinity intrusion zone of this delta from 1975 to 2016. We interviewed 32 farmers in Tra Vinh Province and used transcript analysis to quantify the influence of the drivers that the farmers mentioned. We then compared the drivers of land-use change with those found earlier in the highly flooded zone. Results show more diversification of land uses and land-use changes in the salinity intrusion zone. Farmers here followed three main pathways: rice intensification, integrated farming of rice and vegetables/aquaculture, or intensive shrimp farming. Land-use changes were conditional on the regional infrastructure construction to preserve freshwater conditions. However, household-scale drivers, especially natural and financial assets, were most frequently mentioned. Socio-economic context also emerged as an important driver, particularly trends and pressures from the community and markets.

We present analog experiments on dike propagation, followed by a numerical model of horizontal and vertical growth, which is partially analytical and partially based on empirical observations. Experimental results show that the growth rates are similar until buoyancy becomes significant and, afterward, vertical growth dominates. The numerical model is defined for different conditions in a homogeneous medium: (a) constant flux, fracture‐limited propagation; (b) constant flux, viscous‐limited propagation; and (c) variable flux dependent on the driving pressure and dike dimensions. These conditions distinguish between cases when the influx depends on the deeper source of magma (e.g., a conduit, independent of the dike geometry) and when it depends on the dike, so the influx can change as it grows. In all cases, the ratio of vertical to horizontal propagation is proportional to the ratio of buoyancy pressure to source pressure, in which buoyancy drives vertical propagation. We test the numerical model on dikes observed at Piton de la Fournaise, in which the dimensions were estimated using geodetic and seismic data. The results show that the final dimensions can be reproduced using magma‐crust density differences of 50–300 kg/m3, viscosities of 30–300 Pa·s, influxes of 50–750 m3/s and shear moduli of ∼10 GPa. The modeled magma and host rock parameters agree with previous studies of the volcano, while the flux is higher than what is typically observed during eruption. This implies a variable injection condition, in which the flux peaks during propagation and diminishes by the onset of eruption. Plain Language Summary: Magma‐filled cracks, or "dikes," grow through the Earth's crust and can feed volcanic eruptions. Building reliable models of how they grow is important for forecasting future eruptions. Mathematical models of dike growth commonly consider growth in length only, which allows for simplifications that make it efficient to run simulations. More‐complex 3D simulations tend to require powerful computers and can take a long time to complete. We present a new model that simplifies the dike to an ellipsoidal shape, like a flattened sphere. This model allows dikes to grow in a way that matches experiments and shows that the growth depends on physical forces like buoyancy. When dikes have a low buoyancy, they can grow both vertically and horizontally, but as they become more buoyant, they grow primarily vertically. We test our model against past eruptions at Piton de la Fournaise, a highly active volcano located off the eastern coast of Madagascar. We find that under certain conditions, the model can reproduce the sizes of the dikes. These conditions help us to understand what happens at this volcano specifically, but also how other volcanoes can behave in general. Key Points: Analog experiments indicate that dike propagation in the vertical and horizontal directions depends on the buoyancy and source pressureWe define a numerical model in which growth depends on influx and different pressure ratios, which evolve with timeThe model reproduces the geometries and velocities for nine dikes in nature, using plausible values for magma and host rock rheology [ABSTRACT FROM AUTHOR]

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Cotopaxi is a large, ice-capped stratovolcano located in the Ecuadorian Andes. After 72 years of repose, Cotopaxi erupted on August 14, 2015. The precursory activity included long-period (LP) events followed by volcano-tectonic (VT) earthquakes, very-long-period events accompanying LP signals (VLP/LP events), tremor, deformation and SO 2 emissions. VLP/LP events were first observed at Cotopaxi in 2002, and persistently occurred from 2009 to 2014 and during the 2015 eruptions. Previous studies of the VLP/LP seismicity suggested that these events originated by repetitive volume changes in a crack due to degassing of water from magma at a depth of 2–3 km beneath the NE flank. Based on this interpretation, we estimated the magma volumes related to individual VLP/LP events from 2009 to 2015, which were systematically extracted from continuous seismic records of the Cotopaxi broadband seismic network. Based on the accumulated magma volume and the VLP/LP activity, our study is divided into seven periods (phases A − G), during which the magma supply rate significantly fluctuated. In phase E (June 1–July 27, 2015), before the eruptions, the magma supply rate increased. Degassing at the VLP source generated gas flows in the conduit and pre-eruptive tremor, gradually drying out a shallow hydrothermal system. In phase F (July 28–September 15, 2015), we estimated the highest magma supply rate, leading to magma fragmentation at the VLP source and eruptions accompanied by tremor. In phase G (September 16–December 29, 2015), the magma supply rate decreased, and overall eruptive activity, VLP/LP events, and tremor gradually waned. These results indicate that the VLP/LP events were likely generated by degassing from magma supplied to the VLP source through an intruded dike before and during the eruptions. The VLP/LP activity provides critical useful information about the magma supply rates that controlled eruptive and gas emission activity at Cotopaxi during this period and may help to constrain magma volumes during future reactivations. • VLP/LP events are related to the overall seismic activity and SO 2 emissions during pre-eruptive and eruptive periods. • Seismic patterns indicating heightened activity and impending eruptions. • New methodology to quantify magma volume using a non-destructive VLP source at the volcano. • Degassing changes occur during passive and active states, and when the volcanic system's conduit becomes more open. [ABSTRACT FROM AUTHOR]

Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate‐rich seawater. Yet, widespread management of coastal hydrology has restricted tidal exchange in vast areas of coastal wetlands. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls and scaling of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here, we (1) examine how carbon fluxes vary across a salinity gradient (4–25 psu) in impounded and natural, tidally unrestricted Phragmites wetlands using static chambers and (2) probe drivers of carbon fluxes within an impounded coastal wetland using eddy covariance at the Herring River in Wellfleet, MA, United States. Freshening across the salinity gradient led to a 50‐fold increase in CH4 emissions, but effects on carbon dioxide (CO2) were less pronounced with uptake generally enhanced in the fresher, impounded sites. The impounded wetland experienced little variation in water‐table depth or salinity during the growing season and was a strong CO2 sink of −352 g CO2‐C m−2 year−1 offset by CH4 emission of 11.4 g CH4‐C m−2 year−1. Growing season CH4 flux was driven primarily by temperature. Methane flux exhibited a diurnal cycle with a night‐time minimum that was not reflected in opaque chamber measurements. Therefore, we suggest accounting for the diurnal cycle of CH4 in Phragmites, for example by applying a scaling factor developed here of ~0.6 to mid‐day chamber measurements. Taken together, these results suggest that although freshened, impounded wetlands can be strong carbon sinks, enhanced CH4 emission with freshening reduces net radiative balance. Restoration of tidal flow to impounded ecosystems could limit CH4 production and enhance their climate regulating benefits. [ABSTRACT FROM AUTHOR]

Post‐rifting ground deformation may be driven by viscoelastic relaxation of stresses generated by dike intrusions. The single‐dike intrusion of the 2014–2015 Bárðarbunga eruption in Iceland presents an opportunity for a detailed study of this process. We use continuous Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) velocity fields to analyze the 2015–2020 post‐rifting deformation, showing uplift on both sides of the dike and horizontal displacement away from the dike after correcting for background deformation. Two GNSS stations experience baseline lengthening at a rate of 19 mm/yr in the direction perpendicular to the strike of the dike. A two‐layer viscoelastic model with a 0.4 × 1019 Pa s viscoelastic half‐space overlain by an 18 km thick elastic layer best explains the observed horizontal and vertical InSAR and GNSS displacements. The model misfit space shows a second regime of good fit, likely driven by deformation near the dike that may result from cooling compaction of the emplaced dike. Plain Language Summary: Surface displacement can continue for years after a fissure eruption ends. This has been found at some volcanoes, such as in Afar (Ethiopia) and Krafla (Iceland). The 2014–2015 Bárðarbunga eruption in Iceland created a 48 km long dike, that led to an eruption to the northeast of the Bárðarbunga caldera outside the Vatnajökull ice cap. Here, we focus on exploring an explanation for the surface movement in the dike area after the eruption. Other non‐volcanic processes cause surface movements in the area, including glacial isostatic adjustment caused by the ice retreat and plate spreading due to the divergence of the Eurasian plate and North American plate. We first correct for deformation due to these processes. The remaining deformation signal shows uplift on both sides of the dike and horizontal displacement away from the dike. We test if a two‐layer model consisting of an elastic layer on top of a viscoelastic half‐space can explain our observations. Our results suggest that material properties similar to other nearby areas explain the observations well. Systematic difference between observed and modeled deformation near the dike feeding the eruption is likely due to its cooling. Key Points: Interferometric Synthetic Aperture Radar (InSAR) & Global Navigation Satellite System (GNSS) velocities indicate ∼19 mm/yr widening across a dike after its formation interpreted as post‐rifting viscoelastic relaxationA two‐layer viscoelastic model with 0.4 × 1019 Pa s viscoelastic half‐space below 18 km depth best explains the GNSS and InSAR observationsElastic thickness of ∼18 km provides best fit, but a comparable fit is at ∼2 km, most likely due to unmodeled processes [ABSTRACT FROM AUTHOR]

Summary: The increase in the number of hydrogen (H2) fuel cell vehicles necessitates the swift installation of requisite infrastructure such as H2 refueling stations (HRSs). However, the use and storage of high‐pressure gaseous H2 in conventional HRSs limits inventory and poses safety risks. In this regard, ammonia (NH3) is a potential solution as an H2 carrier with high storage capacity that can be stored as a liquid. However, NH3 is toxic and accidental exposure to it is fatal for humans. Therefore, this study aims to develop a process and safety design for HRSs using NH3 as the H2 carrier. The operation of ammonia‐derived H2 refueling stations comprises dehydrogenation and refueling processes, for which quantitative risk assessment was performed based on process design data. Consequently, it was determined that NH3 leakage from the storage tank was the dominant accident scenario and that the associated risk exceeded the acceptable risk criteria. Therefore, we proposed a risk mitigation strategy that involves installing a dike to guarantee safe design and operation. [ABSTRACT FROM AUTHOR]

Abstract We herein propose an alternative model for deformation caused by an eruption at Sakurajima, which has been previously interpreted as being due to a Mogi-type spherical point source beneath Minami-dake. On November 13, 2017, a large explosion with a plume height of 4200 m occurred at Minami-dake. During the 3 min following the onset of the explosion (November 13, 2017, 22:07–22:10 (Japan standard time (UTC + 9); the same hereinafter), phase 1, a large strain with changes up to 120 nstrain was detected at the Arimura observation tunnel (AVOT) located approximately 2.1 km southeast from the Minami-dake crater. After the peak of the explosion (November 13, 2017, 22:10–24:00), phase 2, a large deflation was detected at every monitoring station due to the continuous Strombolian eruption. Subsidence toward Minami-dake was detected at five out of six stations, whereas subsidence toward the north of Sakurajima was detected at the newly installed Komen observation tunnel (KMT), located approximately 4.0 km northeast from the Minami-dake crater. The large strain change at AVOT as well as small tilt changes at all stations and small strain changes at the Harutayama observation tunnel (HVOT) and KMT during phase 1 can be explained by a very shallow deflation source beneath Minami-dake at 0.1 km below sea level (bsl). For phase 2, a deeper deflation source beneath Minami-dake at a depth of 3.3 km bsl was found in addition to the shallow source beneath Minami-dake, which turned inflation after the deflation that occurred during phase 1. However, this model cannot explain the tilt change of KMT. Adding a spherical deflation source beneath Kita-dake at a depth of 3.2 km bsl can explain the tilt and strain change at KMT and the other stations. The Kita-dake source was also found in a previous study of long-term ground deformation. Not only the deeper Minami-dake source M D, but also the Kita-dake source deflated due to the Minami-dake explosion.

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