Conduit Flow Research Articles

Mental State Prediction Using Machine Learning and EEG Signal

One of the most exciting areas of computer science right now is brain-computer interface (BCI) research. A conduit for data flow between both the brain as well as an electronic device is the brain-computer interface (BCI). Researchers in several disciplines have benefited from the advancements made possible by brain-computer interfaces. Primary fields of study include healthcare and neuroergonomics. Brain signals could be used in a variety of ways to improve healthcare at every stage, from diagnosis to rehabilitation to eventual restoration. In this research, we demonstrate how to classify EEG signals of brain waves using machine learning algorithms for predicting mental health states. The XGBoost algorithm's results have an accuracy of 99.62%, which is higher than that of any other study of its kind and the best result to date for diagnosing people's mental states from their EEG signals. This discovery will aid in taking efforts [1] to predict mental state using EEG signals to the next level.

Pendugaan Aliran Conduit Sistem Akuifer Kawasan Karst Gua Pindul Gunung Kidul Menggunakan Metode Geolistrik Konfigurasi Wenner

Karst areas contain limestone lithology that is easily dissolved by water, so rainwater can accelerate the process of dissolving rocks below the surface and forming cavities. The hydrological system of the Pindul area has a conduit flow karst aquifer type. The components of conduit flow are open channels and pipe-like passages that have various shapes. The distribution and direction of conduit flow control the Pindul Cave karst aquifer system in Gunung Kidul. The wenner configuration resistivity geoelectric method can determine the presence of a subsurface—conduit flow in karst areas by knowing the difference in rock-specific resistance values. Resistivity geoelectric measurements were carried out using 8 tracks with each track length of 200 meters. The results of data processing and interpretation of the resistivity cross-section show the presence of conduit flow in 5 passes with a resistivity value of 0.174-25 Ωm. The results of the study can provide an overview to determine the subsurface river area.

Air vessel sizing approach for pipeline protection using artificial neural networks

Water hammer is the unsteady flow in conduits due to sudden change of velocities in pipelines and poses it to danger. Sensitivity analysis is performed to show the effect of pump and pipeline parameters on the maximum and minimum head just downstream the pump after pump power failure. A new approach to find the required gas volume in a hydropneumatic tank (air vessel) to protect the pipeline using artificial neural networks (ANNs) is introduced. About 760 runs were generated using Bentley Hammer v8i. For each run, the maximum and minimum head just downstream the pump were calculated for a pump power failure. Two MATLAB codes are written to use networks for finding the best design that guarantees the pressure in the pipeline is within the allowable range. The results showed that pump inertia and wave celerity have a very small effect on the maximum and minimum heads.

Episodic Magma Hammers for the 15 January 2022 Cataclysmic Eruption of Hunga Tonga‐Hunga Ha'apai

AbstractUnderstanding the forces and magma system dynamics on timescales of seconds to minutes remains challenging. In the January 2022 phreatoplinian Hunga Tonga‐Hunga Ha'apai eruption, four remarkably similar seismic subevents within a 5‐min interval occurred during the intensifying early eruptive phase. The subevents are similar in waveforms and durations (∼25 s each). Each subevent begins with an unusual negative P‐wave polarity which is inferred, using full‐wave seismic modeling, to be caused by an upward single‐force mechanism at the volcano created by a magma hammer likely in response to magma flow blockage/constriction during the early part of the eruption as discharge rapidly increased over orders of magnitude with concomitant conduit geometry evolution and instability. Our proposed episodic magma hammer model is consistent with thermodynamic and phase properties of the magmatic mixture, and yields an estimate of conduit mass flow in agreement with vent discharge rates derived from satellite imagery of plume heights.

Near-Bottom Magnetic Anomaly Features and Detachment Fault Morphology in Tianxiu Vent Field, Carlsberg Ridge, Northwest Indian Ocean

As a product of hydrothermal mineralization at spreading centers, seafloor massive sulfides (SMS) have become a research hotspot in the field of prospecting and exploring deep-sea mineral resources owing to their enrichment of various strategic metals. Since hydrothermal circulation changes the magnetic properties of host rocks and can generate magnetic anomalies, near-bottom magnetic surveying is an effective method to determine magnetic anomaly features of the seafloor. This technology has been applied to the detection of SMS deposits, in addition to its use in understanding hydrothermal fluid flow conduits and associated hydrothermal alterations. The Tianxiu Vent Field (TVF) is a detachment-fault-controlled, ultramafic-associated hydrothermal system located on the Carlsberg Ridge, Northwest Indian Ocean. During China’s DY57th cruise in 2019, near-bottom magnetic data were collected by an autonomous underwater vehicle. In this paper, we use bathymetric and magnetic data, as well as rock sampling information, to analyze and discuss the magnetic anomaly features of the TVF region. Then, we apply 2.5D magnetic anomaly profile forward modeling to determine the shallow magnetic structure and the pattern of detachment faults in the subsurface. Our results show that TVF is characterized by a significant positive magnetic anomaly, where stronger magnetization exists in the area with active hydrothermal vent clusters. The detachment fault has a dip of less than 30° at shallow depths, which steepens to a dip of ~70° at depths of around 300 m.

FRC transplantation restores lymph node conduit defects in laminin α4-deficient mice.

Fibroblastic reticular cells (FRCs) play important roles in tolerance by producing laminin α4 (Lama4) and altering lymph node (LN) structure and function. The present study revealed the specific roles of extracellular matrix Lama4 in regulating LN conduits using FRC-specific KO mouse strains. FRC-derived Lama4 maintained conduit fiber integrity, as its depletion altered conduit morphology and structure and reduced homeostatic conduit flow. Lama4 regulated the lymphotoxin β receptor (LTβR) pathway, which is critical for conduit and LN integrity. Depleting LTβR in FRCs further reduced conduits and impaired reticular fibers. Lama4 was indispensable for FRC generation and survival, as FRCs lacking Lama4 displayed reduced proliferation but upregulated senescence and apoptosis. During acute immunization, FRC Lama4 deficiency increased antigen flow through conduits. Importantly, adoptive transfer of WT FRCs to FRC Lama4-deficient mice rescued conduit structure, ameliorated Treg and chemokine distribution, and restored transplant allograft acceptance, which were all impaired by FRC Lama4 depletion. Single-cell RNA sequencing analysis of LN stromal cells indicated that the laminin and collagen signaling pathways linked crosstalk among FRC subsets and endothelial cells. This study demonstrated that FRC Lama4 is responsible for maintaining conduits by FRCs and can be harnessed to potentiate FRC-based immunomodulation.

Experimental evaluation of the flow resistance of CO2 foam fracturing fluids and simulation prediction for fracture propagation

Shale gas fracturing requires huge amounts of water, but most well pads are located mainly in hilly areas where water is scarce. Water supply issues have limited the industrialization of shale gas development. CO2 foam fracturing fluids can meet the requirements for large-scale hydraulic fracturing of shale gas and relieve pressure on water resources. Friction calculations of CO2 foam fracturing fluids in conduit flow are key to the reliability of overall fracturing procedures, affecting fracture targeting and reservoir stimulation effects. Through the analysis of the experimental data of carbon dioxide foam fracturing fluid flow under the simulated reservoir conditions, the influence of pressure, temperature, shear rate, foam quality and other factors on the friction characteristics of CO2 foam fracturing fluid was obtained, and the mathematical calculation model of the friction coefficient of CO2 foam fracturing fluid was established, and the pipe string friction and bottom hole pressure during the fracturing process were obtained, Thus, the shape and extension behavior of hydraulic fractures in the process of carbon dioxide foam fracturing in shale reservoir are simulated and predicted, which provides a theoretical basis for effective evaluation of fracturing effect.

Toward the estimation of the transfer coefficient in karst systems: Using baseflow recession coefficient under matrix-restrained flow regime

Using the reservoir model theory, this study developed an equation for the relationship between the transfer and recession coefficients under a matrix-restrained flow regime. Assuming Darcy's law, the proposed equation was developed based on conventional parameters of karst systems, such as recession coefficient, specific yield, and catchment area. Firstly, the equation was evaluated through forward and inverse modeling of an idealized karst system with MODFLOW-2005 Conduit Flow Process (CFP) and KarstMod, respectively. Then, calibration of a KarstMod and a CFP model of the Baget karstic watershed in France was carried out to check the efficiency of the developed equation.Results of the first step showed that the optimal value of the transfer coefficient based on KarstMod for the linear transfer flow is very close to the baseflow recession coefficient values. Therefore, the transfer coefficient in KarstMod may be considered as the recession coefficient from the matrix to the conduit compartment. Moreover, substituting these two coefficients in the developed equation caused less than 10% errors in estimating the transfer coefficients assigned to the idealized models in CFP. In addition, adding the recession coefficient as prior information in the calibration process affects the recession coefficient of the simulated time series and provides a reliable evaluation of the internal dynamics of the system. Therefore, the results of this research show that the recession coefficients can be used as an initial estimate of the transfer coefficient in the baseflow condition. This achievement can significantly assist the discrete-continuum model calibration and further support the water balance calculations based on the recession data.

Time–frequency signal analysis of flow pulsation in siphon outlet conduit based on HHT considering the pump‐conduit interaction

AbstractThe unsteady three‐dimensional numerical simulation calculation of the vertical axial flow pump device is performed based on CFD to examine the pressure pulsation and energy distribution features of the water flow within the siphon outlet conduit (SOC) under the hydraulic coupling of the pump and the flow conduit. The pressure pulsation signals (PPS) of monitoring points are decomposed using the Hilbert–Huang approach via empirical mode decomposition (EMD) and Hilbert spectrum analysis. The results show that the PPS of monitoring points of the SOC has no obvious periodicity. The low‐frequency range below 20 Hz serves as the primary frequency, and the energy ratio of the high‐frequency signal above 700 Hz is less than 1%. Under the condition of a small flow rate 0.3Qbep, there is obvious high‐frequency pulsation above 500 Hz at the inlet of the upstream section of the SOC, and there are periodic components distributed around 200 Hz. The energy of the pressure pulsation is primarily focused in the low‐frequency range below 40 Hz at the SOC outlet section. The PPS at the top and bottom monitoring points of the hump section are consistent, and the pressure pulsation energy (PPE) is mainly concentrated in the low frequency below 40 Hz. In both the big flow condition (1.2Qbep) and the optimal flow condition (1.0Qbep), the PPE of the monitoring points at the top of the hump section is distributed in the middle and low‐frequency band below 40 Hz, and the energy of monitoring points at the bottom of the hump section is concentrated in the low‐frequency band below 20 Hz, accounting for more than 70%. When the flow rate increases from 0.3Qbep to 1.2Qbep, the peak value of the pressure pulsation coefficient at the main frequency of each monitoring point at the top of the hump section changes little, and the peak value of the pressure pulsation coefficient at the main frequency of each monitoring point at the bottom increases first and then decreases. From the upstream section to the hump section of the SOC, the average frequency of each intrinsic mode function (IMF) of the PPS under different flow conditions shows an overall increasing trend. From the hump section of the SOC to its outlet, the average frequency of each IMF of the PPS decreases under the conditions of 1.0Qbep and 1.2Qbep, and there is no obvious change under the condition of 0.3Qbep.

Interpreting Concentrations Sampled in Long-Screened Wells with Borehole Flow: An Inverse Modeling Approach.

New approaches are needed to assess contaminant mass based on samples from long-screened wells and open boreholes (LSW&OB). The interpretation of concentration samples collected in LSW&OB is complicated in the presence of vertical flow within the well. In the absence of pumping (i.e., ambient conditions), the well provides a conduit for flow to occur between aquifer layers or fractures as a result of head differences. Under pumping conditions, vertical borehole flow may vary with depth depending on far-field heads and hydraulic conductivity; furthermore, if pumping fails to overcome ambient gradients, outflow from the well to the aquifer may occur. Concentration samples thus represent flow-weighted averages of formation concentrations, but the averaging process is commonly unknown or difficult to identify. Recognition of the importance of borehole flow has motivated the use of multi-level wells, packers, and well liners; however, LSW&OB remain common for numerous reasons, including cost, multi-purpose design requirements (e.g., pump-and-treat, water supply), logging, and installation of instrumentation. Here, we present a simple analytical model for flow and transport within a well and interaction with the surrounding aquifer. We formulate an inverse problem to estimate formation concentration based on sampled concentrations and data from flowmeter logs. The approach is demonstrated using synthetic examples. Our results (1) underscore the importance of interpreting sampled concentrations within the context of hydraulic conditions and aquifer/well exchange; (2) demonstrate the value of flowmeter measurements for this purpose; and (3) point to the potential of the new inverse approach to better interpret results from samples collected in LSW&OB.

Research in Velocity Profile and Pressure Distribution in 2D Conduit Flow with Stagger Arranged liquid separator blocks

This work uses ANSYS Fluent commercial software to develop a pipe liquid separator model with inside staggered arranged diamond-rectangular shaped blocks for liquid separating. This model serves to liquid separating process in large diameter pipes. All computations are conducted under laminar flow with 200 iterations, and the residues are constantly monitored to ensure accuracy. Two different block sizes and two different inlet velocities are tested for comparison and analysis. Streamline plots and pressure contours are plotted and analyzed for separating performance and pressure drop. The model works well on separating for any combination of inlet velocity and block size. Velocity does not influence performance a lot, but larger blocks have better performance. The pressure drop is significant in these models. Increasing velocity or block size would greatly increase pressure drop, which means the model may work at low velocity for a pressure-sensitive environment. The fitted math relationship between parameters is not fully analyzed and could be developed in future work.

Mid-crustal reactivation processes linked to frictional melting and deep void development during seismogenic slip: examples from the Lewisian Complex, NW Scotland

Exhumed examples of ancient fault voids formed during seismic slip at depths >10 km are well preserved in the Assynt Terrane of the Lewisian Complex, NW Scotland. They are interpreted to have formed during regional Mesoproterozoic ( c. 1.55 Ga; ‘Assyntian’) strike-slip faulting. Deformation is characterized by sinistral reactivation of pre-existing NW–SE-trending features including intrusive contacts of ( c. 2.4 Ga) mafic dykes and Paleoproterozoic ductile shear zone fabrics ( c. 1.75 Ga). Reactivation occurred at palaeodepths of 10–15 km, where frictional–viscous deformation synchronous with co-seismic frictional melting led to cycles of millimetre- to decimetre-scale cavity dilation and collapse. Although individual melt-generating slip surfaces may have become rapidly welded, faulting was able to repeatedly localize along adjacent pre-existing planar anisotropies favourably oriented for slip, leading to the creation of a mesh of foliation-parallel melt generation surfaces linked by foliation-perpendicular dilational voids. The latter features are filled by chaotic clast-supported wall rock collapse breccias, localized injected frictional melts and hydrothermal mineralization. The fills act as natural props, holding cavities open and preserving them as long-term, pipe-like fluid flow conduits. These exhumed features are likely to be typical of multi-rupture seismogenic fault systems formed by direct reactivation of pre-existing basement structures.

Identification of groundwater potential zones in the Rabigh-Yanbu area on the western coast of Saudi Arabia using remote sensing (RS) and geographic information system (GIS)

The groundwater potential zones in the Rapigh-Yanbu area, on the west coast of Saudi Arabia, were evaluated using remote sensing and geographic information system data leading to the establishment of major watershed development and management strategies. Many factors, including slope, drainage density, land use, geology, lineament density, elevation, yearly precipitation, and soil type distribution, affect the hydrogeological characteristics of coastal aquifers. The Rabigh-Yanbu coastline groundwater potential zones were located and mapped using these characteristics. The annual precipitation rate is categorized into 2–28 mm, 29–52 mm, 53–76 mm,77–107 mm, and 108–164 mm within the study area. The highest elevation was ordered with the lowest rank of 1, while the lowest elevation was given the highest rank of 5. Slopes of 0°–9° were present in the majority of the study region, while slopes of 9°–63° were present in the northwest. Based on the slope, the research area was separated into five classes; 0-3o; 4-9o; 10–16o; 17–25o; 26–63o. Based on the drainage density map; 0–0.36 km2, 0.37–0.53 km2, 0.54–0.73 km2, 0.74–1.32 km2, 1.33–3.31 km2. The majority of the fractures trended NE–SW and NW–SE. A map of lineament density was made using the line density method. This map makes it obvious that the region was divided into five classes; 0–0.02 km2, 0.03–0.08 km2, 0.09–0.13 km2, 0.14–0.2 km2, and 0.21–0.34 km2. The classification of soil types in the study region into four classes such as clay loam, clay, sandy clay, and loam. Accordingly, the clay soil was ranked 1, while the loam soil was given the highest rank of 4. The Precambrian rocks had low groundwater potential because of their reduced porosity and were ranked 1, while Quaternary deposits had a high porosity and good groundwater potential and were given a high rank of 3. According to the likelihood of groundwater supply, the area is divided into four categories: very good, good, moderate, and poor. The area with very good groundwater potential covered 1,384 km2, while the area with good groundwater potential covered 30,498 km2, according to the findings. The study area had 34,412 km2 of somewhat appropriate land for groundwater development. In contrast, 1,734 km2 of the study area is scarce. The best zones featured the lowest slopes, the least number of lineaments, and the most drainage. The lineaments, which serve as the main conduits for groundwater flow and storage, have significant levels of groundwater recharge capacity in the study area. Managing groundwater according to these identified potential zones will maximize their benefits and increase the groundwater yield. This will help in creating new agricultural, urban, and industrial communities in this strategic area and contribute toward achieving the goals of Saudi Vision 2030.

A model volcanic fissure with adjustable geometry and wall temperature

Fissure eruptions initiate with magma ascending and spreading through cracks in the ground that can extend for kilometres at the surface. Eruptions eventually localise to form one or a few persistent conduits and ultimately an array of discrete cones or craters. We built a new experimental apparatus to investigate the influences of fissure shape and wall-rock temperature on localisation within a volcanic fissure, and the thermal feedbacks associated with variability of these parameters. Our artificial fissure, or “Artfish,” has a slot geometry with adjustable shape and wall temperature. We can simulate both starting variability in fissure geometry and wall temperature, as well as changes in these parameters during an experiment to replicate, for example, blockage by wall-rock collapse, widening by wall-rock erosion, and warming by adjacent intrusions. We use polyethylene glycol (PEG 600) for our analogue fluid. A variable-speed pump allows for a range of fluid injection and ascent rates. Initial tests showcase the capabilities of the model and the types of data that may be acquired. Additional key features achieved include a stable and planar injection system, fluid recycling, and the use of particle tracers for monitoring flow patterns and velocities. The thermal evolution of the fluid-wall interface is quantitatively measured with thermal sensors, and the change in state of the PEG provides a clear visual indication of flow behaviour and solidification progress recorded on video. The potential experiments that can be conducted with this highly versatile model are numerous and will be used to gain a better understanding of the thermal controls on flow localisation and conduit development. This will assist hazard modellers to assess controls on eruption evolution and potentially to forecast sites where an initial fissure eruption may focus.

Remote sensing and geophysical methods for delineating groundwater resources in schists hard rocks of the Adamawa Yadé Domain, Cameroon

The combination of remote sensing and geophysical techniques is a practical approach for mapping environmental hydrogeological setting and delineating groundwater zones. This paper applies an integrated approach to identify and extract the subsurface structures that act as conduits for the groundwater flow in the highly deformed area of the Adamawa region. Remote sensing data through the lineament’s extraction technique highlights topographic lineaments along which rivers flow in the area. The distribution of these lineaments according to the lineament density map indicates the degree of permeability or porosity of each region and thus the capability in terms of groundwater potential. The filtering of aeromagnetic data enables to produce a structural map showing various geophysical lineaments interpreted as the fault systems of the study area. These faults are the main conduits through which magnetized rocks of granitoid type intruded into the basement and groundwater flows to the subsurface. Local application of the vertical electrical sounding (VES) shows that the study area is highly fractured/faulted and composed of multiple lithologic units including two aquifer layers (clayey sands and fractured schists) with thickness ranging from 5 to 15 m and from 34 to 82 m, respectively. Geoelectric cross-sections reveal that the subsurface structures consist of horsts, followed by a progressive subsidence depicted by the NE-trending faults towards the southern depression and grabens bounded by NW- and NE-trending normal faults. These prominent structures (faults, fractures, and grabens) are considered as the conduits for the groundwater flow into hard rock aquifers of the study area.

Free water input into the New Britain subduction zone in Solomon Sea estimated from reflected seismic data

AbstractIt is of great significance to examine the distribution of the fluid within the subduction zone to estimate the water flux into the subduction zone and to study the motion state of the subducting plate. The interaction of the Western Pacific Plate and the Indo‐Australian Plate controls the subduction and expansion of the Solomon Basin where the mechanisms governing plate activity remain unclear but are typically associated with high pore fluid pressures and stabilizing frictional conditions. Combining the long streamer seismic data (200) and nine well logs inside the work area, we used constrained sparse spike inversion to obtain the P‐wave impedance profile. Then we constructed reservoir rock physics models to predict the fluids distribution in New Britain Trench subduction system in Solomon Sea. The genetic algorithm was used to guide the inversion of the pore fluid distribution. The water content profile revealed the shallow structure of the New Britain Trench subduction system in Solomon Sea, including the water content within the basalt layers. We determined that in certain cases, faults identified from the reflection data were associated with low‐impedance anomalies, and this may indicate that they are zones of high porosity that act as conduits for fluid flow. The continuity of the distribution of water content under the New Britain Trench suggests that there is a large amount of free water that subducts deeply and may be important in controlling the motion state of the subducting plate. We assume that the water saturation is 1. Therefore, the free water flux entering the deep circle with the subducting plate is estimated to be 158 Tg/Ma/m totally, including 53.724 Tg/Ma/m in the sediment and 105.06 Tg/Ma/m in the basalt. This study provides insight into the structure of free water in the New Britain subduction zone and reveals the potential for the direct estimation of the 2D structural distribution of water content using geophysical survey data.

Preferential flow between rivers and aquifers in alluvial floodplains: A key to modelling and sustainably managing shallow groundwater resources

AbstractPreferential flow between rivers and aquifers in alluvial floodplains may be a core component of shallow groundwater transport and, consequently, its understanding is key to modelling and managing groundwater resources. At a clay wedge separating present‐day streamflow and bank storage from an adjacent shallow aquifer, we image a suspected sand‐dominated structure. This structure cuts through the clay wedge and possesses temporally dynamic electrical resistivity as seen in time‐lapse electrical resistivity tomographic (ERT) images collected over a 61‐day study period. During days 11–12, following heavy rainstorms, the cross section of the electrically resistive sand fades into the background resistivity structure, reappearing the following day. This research shows that preferential flow can be imaged in time‐lapse ERT in buried sand‐dominated structures between a floodplain and the adjacent river. Our analysis demonstrates that sand conduits can transport infiltrated rainwater from the floodplain into the river as a bank spring and, hypothetically, at high‐stage streamflow, from the river into the adjacent shallow aquifer. In both directions, these conduits for preferential flow exert an important control on the regulation and distribution of water, sediments and contaminants. This phenomenon will help hydrological models to incorporate more real‐world phenomena and ultimately better prepare groundwater managers to sustainably steward shallow groundwater resources.

Phosphogypsum weathering and implications for pollutant discharge into an estuary

Approximately 100 million tons of phosphogypsum were stockpiled onto marsh soils of the Tinto River estuary (Huelva, SW Spain). This study focuses on the hydraulic response of the phosphogypsum stack to the different weathering agents, as well as on the hydrochemical behavior of highly acidic and polluted effluents from its leaching during different hydrological conditions. To address these issues, a CTD-Diver was installed in a bore-hole within a phosphogypsum stack profile, which recorded the variations in the water-table of the stack, and edge outflows samples were collected around the perimeter of the stack during four sampling periods in different seasons. During dry periods, the water-table of the stack remains almost static and is controlled only by the tide oscillations. However, during rainy events this water-level rapidly increases up to 20 cm and subsequently decreases, defining peaks that coincide with the rainfalls. Having a hydraulic connection to the sea and groundwater flow in conduits, the phosphogypsum stack behaves as an anthropogenic karstic-coastal aquifer. Regarding the hydrochemical behavior of the edge outflows, the concentrations of most pollutants (e.g., PO4, Al, As, Cd or U) showed a slight decrease from the dry-warm to the rainy period. These leachates releases high concentrations of contaminants to the estuary, e.g., PO4, As and U (average values of 5000, 6.9 and 3.0 t/yr, respectively). The results obtained in this study could contribute to the development of effective treatment systems for leachates from phosphogypsum stack of Huelva and to minimize their impact on the surrounding estuarine environment.

Constraints on Magma Properties at Fragmentation During the 2011 Sub‐Plinian Eruptions of Kirishima Shinmoe‐dake Volcano, Japan

AbstractWe investigated essential factors controlling magma fragmentation during the 2011 sub‐Plinian eruptions of Kirishima Shinmoe‐dake volcano, Japan, based on observational data and the analysis of the conduit flow system. Key observational data of the Shinmoe‐dake eruptions are geophysically estimated magma discharge rate and petrologically measured crystallinity and porosity at the time of fragmentation. Using formulations of fragmentation criterion and conduit flow model, we derived analytical expressions describing the relationship among magmatic and geological parameters at the time of strain rate‐induced or stress fragmentation. The combination of the observational data and the analytical expressions revealed the relationship among weakly constrained parameters at the fragmentation, such as pressure, gas permeability in the magma, conduit radius, and maximum packing fraction of crystals, β*. From this relationship, we found that a smaller β*, less than approximately 0.5, is necessary for the fragmentation to occur for a wide range of the conduit radii under realistic pressure and gas permeability values. This reflects that in the case of the sub‐Plinian eruption with a moderate magma discharge rate, a drastic increase in magma viscosity induced by the smaller β* plays a crucial role in the occurrence of fragmentation. The strong dependence of the fragmentation process on β* indicates that the suspension rheology of crystal‐bearing magma is an essential factor controlling the magma ascent process during the moderate explosive eruption.

Take it to the bank: A numerical examination of the effects of soil pipes on bypass of riparian buffer nitrate removal capacity

Streams are vital landscape ecosystems, and urbanization and modern agriculture have introduced pollutants (including excess nitrate) which threaten these waterways. Riparian zones have been shown to attenuate pollutants, and riparian buffers are commonly implemented to capture these benefits. Nevertheless, preferential flowpaths such as soil pipes have potential to bypass such attenuation. We used a MODFLOW groundwater model with the conduit flow package (CFP), along with the groundwater transport code MT3D-USGS, to simulate flow of water and nitrate through riparian groundwater to a gaining stream. We conducted a numerical sensitivity analysis to examine the impact of soil pipe presence and characteristics, as wells as soil matrix characteristics, on nitrate transport and uptake by denitrification within the saturated zone. We found that in systems with 2.0-m-long soil pipes, low head gradient (∇h less than 0.0035), low hydraulic conductivity (K < 10−4.75 m/s), and high reaction-constant (k > 4 day−1), soil pipes increased riparian bypass of nitrate by several orders of magnitude. Yet soil pipes increased the volumetric flowrate of water across the riparian zone only by up to 3.9 times. This comparatively greater effect on transport occurred because the accelerated advection of nitrate through the soil pipes decreased the residence time available for denitrification. We created two non-dimensional parameters that show when bypass will be important, the riparian bypass potential (ψ) that accounts for key governing factors such as volumetric flowrate and Damköhler number, and riparian predictive index (ζ), which is calculated from easily measurable parameters. Nitrate bypass starts to increase by orders of magnitude above ψ ≈ 2.75 and ζ ≈ 3.4. Our results emphasize the importance of accounting for soil pipes when constructing riparian buffers and predicting their effects on dissolved pollutant transport.