Surface Disturbance Research Articles

Modeling of the Initial Stage of Wave Generation by a Suddenly Rising or Falling Seabed

In this study, a three-dimensional entirely nonlinear model was used for simulating the wave generation problem caused by seabed movement. This study focuses on the waveform of the initial stage of wave generation. The numerical model was verified by comparing the simulated results with existing experimental results. Satisfactory results of the waveforms and flow fields were obtained. The simulations of the free surface disturbances and flow field velocities caused by the sudden rising or falling of a circular cylinder with the dimensionless radius ([Formula: see text]) and height ([Formula: see text]) normalized by still-water depth are discussed. We considered the combinations of [Formula: see text]–10 and [Formula: see text]–0.3. For the moving cylinder with a moderate height (e.g. [Formula: see text] and [Formula: see text]) and [Formula: see text], it is found that the water-surface shape is closer to the shape of the terrain. The central water level ([Formula: see text]) varying with time is also focused herein. For the rising cylinder, when [Formula: see text], the maximum [Formula: see text] is always less than its corresponding [Formula: see text] for any [Formula: see text]. For the falling cylinder, if [Formula: see text] is larger than five times the still water depth, then the maximum [Formula: see text] will exceed its corresponding [Formula: see text]. This result provides a further understanding of the basic phenomenon of the initial waves caused by the movement of the seabed topography.

Remote Sensing for Surface Coal Mining and Reclamation Monitoring in the Central Salt Range, Punjab, Pakistan

The expansion and exploitation of mining resources are essential for social and economic growth. Remote sensing provides vital tools for surface-mining monitoring operations as well as for reclamation efforts in the central Salt Range of the Indus River Basin, Pakistan. This research demonstrates the applicability of remote sensing techniques to the coal mining monitoring scheme to allow for effective and efficient monitoring and to offset the adverse consequences of coal mining activities. Landsat 8 OLI images from June 2019 and 2020, and a Landsat 7 ETM+ image from June 2002, were used for this study. A three-phase methodology including Normalized Difference Vegetation Index (NDVI) analysis, land cover mapping, and change detection approaches was adopted. Image classification based on Tasseled Cap Transformation and the brightness temperature At-satellite using the K-means algorithm was implemented in a GIS program to identify seven land cover classes within the study area. The results show some level of surface disturbance to the landscape due to the coal mining reclamation activities that had taken place over the 18-year time period. From 2019 to 2020, about 3.622 km2 of coal mines or barren land were converted into bare agricultural land. Over the years, it was also observed that reclamation areas exhibited higher values of NDVI than coal mining areas. The mean NDVI for coal mining areas was 0.252 km2, and for areas of reclamation, it was 0.292 km2 in 2020, while in 2019, the value for coal mining sites was 0.133 km2, and 0.163 km2 for reclamation sites. This trend suggests that coal-mining operations can be monitored using satellite data, and the progress of reclamation efforts can be assessed using satellite NDVI data from the target locations. This study is beneficial to agencies responsible for monitoring land cover changes in a coal mine because it provides a cost-effective, efficient, and robust scientific tool for making mine site allocation decisions and for monitoring the progress of reclamation efforts.

Effect of soil surface disturbance on overland flow, sediment yield, and nutrient loss in a hyrcanian deciduous forest stand in Iran

Disturbance of forest watersheds has numerous effects on up and downstream environments, including erosion and reduction in productivity in disturbed areas, removal of nutrients, and deposition of pollutants on the land surface by runoff contamination of water resources. Little research has been conducted on forest ecosystems despite the environmental problems induced by nutrient transport. Therefore, the present study was conducted to quantitatively compare sediment yield, surface runoff, and nutrient and organic matter (OM) loss from undisturbed and disturbed forest areas during rain events in the Research and Educational Forest Watershed of Tarbiat Modares University in northern Iran. The study involved two treatments with three replications using 6-m2 plots. Results verified the significant effects of forest degradation (P < 0.05) on hydrological components and nutrient and OM loss. The surface runoff volume, runoff coefficient, sediment concentration, and sediment yield from plots located in the disturbed forest area were 5, 7, 5.5, and 18 times more, respectively than those measured in the undisturbed area. Also, the loss of carbon, nitrogen, phosphorus, and potassium in the disturbed area was more than in the undisturbed forest by 5, 10, 16, and 19 times. The maximum rate of loss of nutrients was 25 kg.ha−1. Enrichment ratios for carbon, nitrogen, phosphorus and potassium in the undisturbed area were 1.38 ± 0.33, 1.13 ± 0.11, 0.25 ± 1.86 and 1.24 ± 0.20, respectively, and 0.36 ± 1.59, 0.37 ± 1.57, 0.22 ± 1.98 and 0.29 ± 1.008, respectively, in the disturbed area. The study results should be applied to improve the management of Iranian forest ecosystems.

Air flow inside a vertical pipe induced by a free-falling water jet

The air flow induced by a water jet freely falling inside a vertical pipe with its top and bottom both open to the atmosphere was investigated experimentally and numerically. In the experiments, the radial air velocity distribution and the air pressure variation along the vertical pipe were measured. The air drag of the falling water jet was related to the jet surface disturbance and analyzed by introducing the equivalent friction factor. A predictive model was developed for the air flow inside a 3-m-high pipe based on the momentum equation and its results compared well with the experimental measurements. Numerical simulations were also conducted by approximating the free-falling water jet as a continuous moving solid with diameter and velocity varying in the direction of motion. The effects of pipe size on the air velocity profile and the induced air flow rate were examined. The simulation results showed that the streamwise air velocity profiles inside pipes of different sizes approached the same after a certain traveling distance. The maximum induced air flow rate was found at the pipe diameter of about 20 times of initial water jet diameter.

The Doppler Flip in HD 100546 as a Disk Eruption: The Elephant in the Room of Kinematic Protoplanet Searches

The interpretation of molecular-line data using hydrodynamical simulations of planet–disk interactions fosters new hope for the indirect detection of protoplanets. In a model-independent approach, embedded protoplanets should be found at the roots of abrupt Doppler flips in velocity centroid maps. However, the largest velocity perturbation known for an unwarped disk, in the disk of HD 100546, leads to a conspicuous Doppler flip that coincides with a thick dust ring, in contradiction with an interpretation in terms of a ≳1 M jup body. Here we present new ALMA observations of the 12CO(2–1) kinematics in HD 100546, with a factor of 2 finer angular resolutions. We find that the disk rotation curve is consistent with a central mass 2.1 < M ⋆/M ⊙ < 2.3 and that the blueshifted side of the Doppler flip is due to vertical motions, reminiscent of the disk wind proposed previously from blueshifted SO lines. We tentatively propose a qualitative interpretation in terms of a surface disturbance to the Keplerian flow, i.e., a disk eruption, driven by an embedded outflow launched by a ∼10 M earth body. Another interpretation involves a disk-mass-loading hot spot at the convergence of an envelope accretion streamer.

Modeling and Control of a Fixed-Wing High-Speed UAV

High-speed Unmanned Aerial Vehicles (UAVs) will be an interesting subject of study in today’s aviation technology because of their ingenuity in obtaining high speeds while maintaining good maneuverability. In this study, modeling and control of a fixed-wing high-speed mini-UAV are performed. Aerodynamic analyses of the vehicle with a wingspan of 1.2 meters and a total take-off weight of 1.1 kg are done with the help of some computational fluid dynamics software. A developed MATLAB/Simulink code evaluates flight performance after a doublet control surface disturbance with six-degrees-of-freedom flight simulations in both longitudinal and lateral directions by a developed MATLAB/Simulink code. The transfer functions are obtained by trimming the aircraft at wing-level for a speed of 155 km/h, and the maximum speed that the mini-UAV could reach is calculated as 400 km/h. Two kinds of different linear controllers are designed to hold the pitch angle of the vehicle to the desired value. The time responses of the controllers are represented, and the elevator deflection effort is evaluated. Finally, a compulsive pitch angle is wanted to be tracked by the two controllers, and their responses are compared in terms of performance and stability.

Responses to natural gas development differ by season for two migratory ungulates.

While migrating, animals make directionally persistent movements and may only respond to human-induced rapid environmental change (HIREC), such as climate and land-use change, once a threshold of HIREC is surpassed. In contrast, animals on other seasonal ranges (e.g., winter range) make more localized and tortuous movements while foraging and may have the flexibility to adjust the location of their range and the intensity of use within it to minimize interactions with HIREC. Because of these seasonal differences in movement, animals on seasonal ranges should avoid areas that contain any level of HIREC, however, during migration, animals should use areas that contain low levels of HIREC, avoiding it only once a threshold of HIREC has been surpassed. We tested this hypothesis using a decade of GPS collar data collected from migratory mule deer (Odocoileus hemionus; n=56 migration, 143 winter) and pronghorn (Antilocapra americana; n=70 migration, 89 winter) that winter on and migrate through a natural gas field in western Wyoming. Using surface disturbance caused by well pads and roads as an index of HIREC, we evaluated behavioral responses across three spatial scales during winter and migration seasons. During migration, both species tolerated low levels of disturbance. Once a disturbance threshold was surpassed, however, they avoided HIREC. For mule deer, thresholds were consistently ~3%, whereas thresholds for pronghorn ranged from 1% to 9.25% surface disturbance. In contrast to migration, both species generally avoided all levels of HIREC while on winter range. Our study suggests that animal responses to HIREC are mediated by season-specific movement patterns. Our results provide further evidence of ungulates avoiding human disturbance on winter range and reveal disturbance thresholds that trigger mule deer and pronghorn responses during migration: information that managers can use to maintain the ecological function of migration routes and winter ranges.

Effects of land use and yak grazing on behavior and body mass of plateau pika in Tibetan plateau rangelands

AbstractThe body mass of small mammals is widely regarded as an indicator of habitat quality, with trade‐offs between anti‐predator and energy‐building behaviors noted across many species and habitat conditions as suggested by optimal foraging theory. In this study, however, grazing by domestic yak was noted to mediate this effect, affecting both the body mass and behaviors of plateau pika, Ochotona curzoniae, which deviated from expected ecological patterns. Specifically, we compared conditions of plateau pika at 16 trap sites across a range of habitats on the Tibetan plateau, each characterized by herders according to their seasonal use as winter, spring, or summer pastures, and to their vegetative conditions. Plateau pika body mass at herders' tent sites where female and young domestic yak sleep was about 6% higher than at yak foraging sites and 10% higher than fenced areas (where yak are excluded) despite the additional disturbance encountered at tent sites. Mean body mass of plateau pika also decreased with increasing slope, and adult body mass was lower in spring compared to winter and summer seasons. Furthermore, more pika burrows were found near herders' tent sites, with burrows exhibiting significantly lower vegetation cover. Pika foraging behavior was most frequent in yak bedding areas (near herders' tent sites), and pika vigilant behavior at yak foraging areas. Recalling that foraging and vigilant (predator avoidance) behaviors constitute energy trade‐offs, we speculate that these unexpected findings may result from the combined effects of soil erosion (due to surface disturbances) and fertilization (with yak dung) at yak resting sites, which could enable higher population densities and body masses of plateau pika despite lower vegetation cover at the tent sites – most likely due to critical behavioral adaptations, ecological dynamics such as predator‐prey relations and other multi‐dimensional and nonlinear reasons.

Centrifugal Modeling of the Relationship between Tunnel Face Support Pressure and Ground Deformation in Water-Rich Sandy Soil

To investigate the ground deformation induced by the variation of excess/insufficient support pressure in water-rich sandy soil, a series of centrifuge tests in tunnels located at cover over diameter (C/D) ratios equal to 0.5, 1.0 and 1.5 were carried out. The soil pressure, pore pressure, maximum surface displacement and the ground movement induced by reduced/increased support pressure were investigated. The results show that when the burial depth is large (≥1.5 D), the ground deformation caused by the support pressure is difficult to extend to the surface. When the burial depth is shallow (&lt;1.5 D), the ground disturbance range induced by excess support pressure is approximately fishtail-shaped while it is approximately chimney-shaped induced by insufficient support pressure. For the former, the surface disturbance range can extend horizontally to about twice the buried depth beyond the front of the face and the maximum heave occurred at a distance of approximately buried depth beyond the front of the excavation face. For the latter, the surface disturbance range can extend horizontally to about buried depth beyond the front of the face which was larger than that in dry sandy soil. Based on the centrifuge test, the ground deformation mechanism was analyzed compared with previous studies and a supporting pressure control coefficient was proposed to conduct quantitative analysis of surface displacement induced by support pressure. Finally, the control of support pressure based on the surface displacement was discussed to provide some advice for practical engineering.

Ways to reduce technogenic landscape disturbances in mining production

Iron ore mining is followed by significant disturbances of the earth’s surface caused by both iron ore mining facilities (underground mines and open pits) and disposal of mining and concentration wastes on the surface (waste and substandard ore dumps at underground mines, overburden and oxidized rock dumps at open pits, tailings storage facilities at mining and beneficiation plants). In addition, operation of mining enterprises leads to creating hundreds of kilometers of above-ground pipelines, technological roads and railroads; drilling and blasting operations at underground mines and open pits lead to seismic phenomena and geotectonic disturbances of the surface in the form of sinkholes and craters in places of underground workings. The presented scientific work aims to generalize the practice of measures to optimize landscape disturbances caused by mining and develop individual issues of arrangement and technology of reclamation of disturbed surface areas in conditions of Kryvyi Rih iron ore basin. Technogenic surface disturbances accumulated during the period of economic exploitation of the region require a comprehensive solution in two directions. The first one consists in reducing the rate of new destructive impacts on the state of the relief by switching from extensive methods of deposit exploitation to all-round intensification of production (introduction of low-waste technologies, concentration waste re-treatment, oxidized ores processing, transition to technologies of internal dumping). The second one involves optimization of already formed landscape disturbances through reclamation. It is recommended to implement a number of methods of improving individual technogenic landscape formations by engineering and biological methods.

Double Asteroid Redirection Test (DART): Structural and Dynamic Interactions between Asteroidal Elements of Binary Asteroid (65803) Didymos

NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale planetary defense mission. The target is the binary asteroid (65803) Didymos, in which the smaller component Dimorphos (∼164 m equivalent diameter) orbits the larger component Didymos (∼780 m equivalent diameter). The DART spacecraft will impact Dimorphos, changing the system’s mutual orbit by an amount that correlates with DART's kinetic deflection capability. The spacecraft collision with Dimorphos creates an impact crater, which reshapes the body. Also, some particles ejected from the DART impact site on Dimorphos eventually reach Didymos. Because Didymos’s rapid spin period (2.26 hr) may be close to its stability limit for structural failure, the ejecta reaching Didymos may induce surface disturbance on Didymos. While large uncertainties exist, nonnegligible reshaping scenarios on Didymos and Dimorphos are possible if certain conditions are met. Our analysis shows that given a surface slope uncertainty on Dimorphos of 45°, with no other information about its local topography, and if the DART-like impactor is treated as spherical, the ejecta cone crosses Didymos with speeds ≳14 m s−1 in 13% of simulations. Additional work is necessary to determine the amount of mass delivered to Didymos from the DART impact and whether the amount of kinetic energy delivered is sufficient to overcome cohesive forces in those cases. If nonnegligible (but small) reshaping occurs for either of these asteroids, the resulting orbit perturbation and reshaping are measurable by Earth-based observations.

Let's Talk about Momentum

Let's Talk about Momentum

Resource selection by greater sage‐grouse varies by season and infrastructure type in a Colorado oil and gas field

AbstractEnergy development is one of the most rapidly increasing land uses in North America, so understanding how wildlife respond to different types of energy infrastructure is crucial for informing land‐use policies. Effects of energy development on wildlife habitat use and selection can vary depending on infrastructure type, level of industrial activity, and density. I examined seasonal habitat use and selection of greater sage‐grouse in relation to energy development in a high‐elevation oil and gas field in western Colorado by linking spatially and temporally explicit energy infrastructure layers with telemetry locations of marked females from 2006 to 2014. Objectives were to (1) quantify energy infrastructure around seasonal use locations; (2) examine how seasonal resource selection is affected by energy infrastructure with disturbed versus reclaimed surface and different levels of industrial activity; and (3) assess current surface disturbance and infrastructure density caps. Between 92% and 97% of seasonal use locations had &lt;3% disturbed surface within 1000 m. After accounting for landcover and topography, breeding and wintering females selected locations with less disturbed, reclaimed, and total anthropogenic surface. Breeding females selected locations farther from high‐activity well pads and facilities. In contrast, females selected locations with low to intermediate values of disturbed and reclaimed surface and locations closer to pipelines and roads in summer–fall. This is the first evidence that greater sage‐grouse select locations with energy infrastructure in any season and suggests that responses to energy development may differ between mesic and arid sagebrush ecosystems. Females avoided locations with &gt;1.1%–2.5% disturbed surface during breeding and winter and selected locations with lower densities of active energy features during breeding and roads in winter. Density caps of one active energy feature and 1.5 mi (2.41 km) of road per section were adequate to prevent avoidance except during the breeding season. Disturbance caps should be set at 1.1% disturbed surface and 1.8% total anthropogenic surface in breeding habitat and 2.5% disturbed surface and 3.5% total anthropogenic surface in winter habitat to minimize negative impacts on female habitat selection in this population. Results also support timing restrictions on construction and drilling during breeding and rapid transitioning of well pads from drilling to production.

Rock-to-Metal Ratio: A Foundational Metric for Understanding Mine Wastes

The quantity of ore mined and waste rock (i.e., overburden or barren rock) removed to produce a refined unit of a mineral commodity, its rock-to-metal ratio (RMR), is an important metric for understanding mine wastes and environmental burdens. In this analysis, we provide a comprehensive examination of RMRs for 25 commodities for 2018. The results indicate significant variability across commodities. Precious metals like gold have RMRs in the range of 105–106, while iron ore and aluminum are on the order of 101. The results also indicate significant variability across operations for a single commodity. The interquartile range of RMRs for individual cobalt operations, for example, varies from 465 to 2157, with a global RMR of 859. RMR variability is mainly driven by ore grades and revenue contribution. The total attributable ore mined and waste rock removed in the production of these 25 commodities sums to 37.6 billion metric tons, 83% of which is attributable to iron ore, copper, and gold. RMRs provide an additional dimension for evaluating the impact of materials and material choice trade-offs. The results can enhance life cycle inventories and be extended to evaluate areas of surface disturbances, mine tailings, energy requirements, and associated greenhouse gas emissions.

Outplanting establishment within a contaminated and nonnative invaded semiarid desert riparian corridor

Protected riparian ecosystems crucially important for wildlife habitat and maintaining water resources are often compromised by land use activities, such as mining, in or surrounding protected areas, creating challenges for conservation. Legacies of land use, contamination, and plant invasions can reduce vegetation community quality and hinder conservation and restoration efforts. In a semiarid riparian ecosystem in a US national monument, we conducted experimental outplantings to assess restoration techniques on native perennial species among sites with variable conditions and disturbance histories. Atriplex canescens and Encelia frutescens seedlings were planted at two coarse-textured soil sites that differed in surface exposure (sparse versus moderate woody perennial canopy cover) and disturbance histories (downstream from mine wastes and activities). For both species, exposed soils closer to mine wastes and with several years of active nonnative plant treatments had higher survival, although all E. frutescens died by one year after planting. After two years, A. canescens survival was 87.5%, or 50% higher, than survival in less exposed soils farther downstream from mine wastes. For four native understory perennials, Bothriochloa barbinodis, Bothriochloa saccharoides, Brickellia floribunda, and Tridens muticus, we tested the effects on planting microsite survival of two supplemental restoration treatments, partial buried container irrigation and tube shelters. For the first three species, planting microsites were located at sites with exposed coarse-textured soils (one site) and fine-textured (two sites) soil that differed in exposure. Tridens muticus was planted at the two fine soils sites, but most plants had died by five months after planting. Two years after planting, shelters improved survival of B. barbinodis, B. saccharoides, and B. floribunda by 20.8, 29.2, and 6.25%, respectively, and improved the probabilities of survival by 30.3, 40.4, and 21.3%, respectively. Survival differed among sites, with more plant microsites surviving in fine soils with lower surface exposure, and survival among supplemental treatments differed among sites and species. Outplanting failures often occur within the first few months to years after planting. Assessing short-term plant establishment is important to determine how plants will respond to site conditions, which are more difficult to manage than species selection and supplemental treatments. Continuing to monitor outplants and natural colonization may inform what species will remain viable options for riparian restoration as site and climate conditions change over time.

A Methodology to Assess the Historical Environmental Footprint of In-Situ Recovery (ISR) of Uranium: A Demonstration in the Goliad Sand in the Texas Coastal Plain, USA

In-situ recovery (ISR) has been the only technique used to extract uranium from sandstone-hosted uranium deposits in the Pliocene Goliad Sand in the Texas Coastal Plain. Water plays a crucial role throughout the ISR lifecycle of production and groundwater restoration yet neither the water use nor other environmental footprints have been well documented. The goal of this study is to examine historical records for all six ISR operations completed in the Goliad Sand to identify and quantify parameters that indicate the surface and aquifer disturbances, water use, and radon emissions. Overall, the average mine area was 0.00023 ± 0.00006 acres per pound (ac/lb) U3O8. The average mine pore volume was 48.9 ± 50 gal/lb U3O8 with a minimum affected aquifer volume of 0.51 ± 0.08 cubic feet per pound (cu ft/lb) U3O8. An average of 258 ± 40 gallons (gal) of fluid were disposed per pound (lb) U3O8, with an average of 169 ± 26 gal/lb U3O8 attributed to restoration and 89 ± 36 gal/lb U3O8 attributed to the uranium production phase. The average radon emitted was 1.06 × 10−3 ± 7.4 × 10−4 curies per pound (Ci/lb) U3O8. Goodness-of-fit (R2) values are ≥0.79 for linear regressions of the amount of uranium produced versus mine area, mine pore volumes, mine aquifer volumes, water pumped, and total water disposed. The R2 value for radon emitted was 0.68. However, the water disposed only during the uranium production phase is more strongly correlated to the number of production days (R2 = 0.96) than to uranium production (R2 = 0.84), whereas the volume of water disposed during restoration is more strongly correlated to the “pore volume” (R2 = 0.97) than to uranium production (R2 = 0.90). Pore volume is an industry term used to describe the amount of fluid circulated through the aquifer during the uranium production period and stipulated in bond agreements in order to satisfy groundwater restoration requirements. Models constructed in this study can be used to estimate probable water use and the extent of surface and aquifer disturbances associated with ISR-amenable undiscovered uranium resources in the Goliad Sand. The historical perspective offered by the data compiled and correlations may prove useful to both industry and regulators.

Ocular surface disturbance in patients after acute COVID-19.

BackgroundWe investigated the ocular surface disturbances in COVID‐19 patients discharged from the hospital.MethodsOne hundred and seventy‐nine eyes of 109 healthy participants and 456 eyes of 228 post‐COVID‐19 patients received comprehensive eye examinations; the latter were interviewed with questionnaires on ocular symptoms before and after COVID‐19 diagnosis. Associations of ocular surface manifestations with virological and ophthalmic parameters were evaluated by multivariable mixed linear or logistic regression models.ResultsMean interval between COVID‐19 diagnosis and ophthalmic evaluation was 52.23 ± 16.12 days. The severity of meibomian gland dysfunction (MGD) based on clinical staging was higher in post‐COVID‐19 than healthy eyes (1.14 ± 0.67 vs. 0.92 ± 0.68, p = 0.002) and so was ocular surface staining score (0.60 ± 0.69 vs. 0.49 ± 0.68, p = 0.044). Patients requiring supplementary oxygen during hospitalisation had shorter tear break‐up time (β −1.63, 95% CI ‐2.61 to −0.65). Cycle threshold (Ct) value from upper respiratory samples (inversely correlated with viral load) at diagnosis had an OR = 0.91 (95% CI 0.84–0.98) with new ocular surface symptoms 4 weeks after diagnosis. The presence of ocular surface symptoms 1 week prior to COVID‐19 diagnosis showed an OR of 20.89 (95% CI 6.35–68.66) of persistent or new ocular symptoms 4 weeks afterward.ConclusionsMGD and ocular surface staining are more common and severe in post‐COVID‐19 patients. Patients with higher viral loads have greater risks of ocular surface symptoms. Patients requiring supplementary oxygen are more likely to show tear film instability. Ocular surface evaluation should be considered 1–3 months following hospital discharge for any COVID‐19 patient.

On-Site Measurement on Surface Disturbance Law of Repeated Mining with High Relief Terrain

Underground coal mining in high relief terrain often causes problems such as ground collapse and mountain sliding. This produces disasters such as mountain collapse and landslides, which seriously endangers the ecological environment and human settlements in the coal mining area and causes a series of public security events. To improve and solve the related problems, it is necessary to master the impact law of underground mining on ground surface. Therefore, taking the working face 1310 of Jincheng coal industry as an example, this paper adopts a new and improved RTK measurement technology for field measurement and analyzes the surface disturbance law by using field data. The results show that under the action of repeated mining in high relief terrain areas, there is a sudden subsidence in the flat bottom area of the surface moving basin, the strike influence scope is small, the dip influence scope in the downhill direction is larger, the dip horizontal movement curve loses its antisymmetry, and the dip subsidence curve loses its left-right symmetry. Through the analysis, it is found that the high reverse slope weakens the original disturbance and reduces the influence range of surface mining. On the contrary, repeated mining enhances the original disturbance, expands the influence range of surface mining, and flattens the movement deformation curve. Research results can provide a technical reference for the formulation and implementation of environmental remediation and treatment technologies in mining areas under similar conditions.

Variation of the land surface temperature field in rare-Earth ore mining areas based on temperature downscaling

During the mining process of ionic rare earth elements (REE), mining disturbances, such as land surface excavation, stripped vegetation, injection holes, and tailings discharge, have led to large-scale vegetation degradation and land desertification, ultimately resulting in land surface temperature (LST) differentiation. The surface thermal anomaly is an important ecological parameter, and its spatiotemporal variation has become a powerful tool for identifying surface ecological disturbance. Because the REE mining areas have the characteristics of scattered ore and small areas, it is of great value to obtain LST data with strong practicality and high spatial resolution for sustainable ecological environment monitoring. In this study, the Lingbei mining area in Dingnan County, Ganzhou, China was selected as the study area. Via the use of Landsat and GaoFen-1 (GF-1) remote sensing images, and based on data fusion and the mixed-pixel decomposition method, the temperature downscaling with image fusion and spectral unmixing (TDIFSU) model and the temperature downscaling with data fusion and spectral unmixing (TDDFSU) model were constructed. In addition, they were compared with the commonly used temperature-downscaling disaggregation procedure for radiometric LST (DisTrad) model to explore the accuracy and applicability of different downscaling models for REE mining areas. Finally, based on remote sensing data from the past 20 years, a suitable downscaling model was selected and the temperature difference index (TDI) was used to analyze the spatiotemporal evolutions of ecological disturbances caused by REE mining. The results showed TDDFSU model had the highest accuracy and the smallest mean absolute error (MAE) and root mean square error (RMSE), which were 1.062 K and 1.386 K in February and 0.877 K and 1.094 K in October, respectively, but it had limitations in spatiotemporal study. The accuracy of TDIFSU model was the second, and TDIFSU model based on Landsat data has more advantages in long time series research. DisTrad model has the lowest accuracy. The most suitable model can be selected according to the time span and accuracy; The LST obtained by downscaling can reflect the actual land surface in more detail, and the boundaries between different ground objects were clearer; The high-temperature areas were mainly concentrated in the vicinity of long-term ore occurrences covered with a large amount of tailings. Medium-temperature areas were mainly bare soil and in situ leaching vegetation areas, and low-temperature areas were mainly natural and reclaimed vegetation areas; During the monitoring of the LST in Lingbei mining area for nearly 20 years, the temperature differences caused by different mining activities were revealed, and the land surface disturbance situation has improved after the state actively carried out REE mining environmental control.

Visualization of the evolution of bubbles in the spray sheet discharged from the air-induction nozzle.

The air-induction nozzle greatly reduces drift potential by increasing spray droplet size compared with a standard flat-fan nozzle. The current study aims to reveal the mechanism behind the formation of large droplets through the air-induction nozzle from the aspect of bubble evolution in the spray sheet. Bubble break-up leads directly to the formation of perforations because large bubbles reach both sides of the spray sheet. The surface disturbance induced by bubble break-up modulates spray sheet thickness, which indirectly leads to the generation of perforations. Compared with the spray pressure, nozzle configuration has a more significant effect on both the volumetric flow rate of intake air and the thickness of the spray sheet. As the nozzle is changed from ID-120-01 to ID-120-05, the volumetric flow rate of intake air increases by 801.30% at a spray pressure of 0.3MPa, whereas spray sheet thickness increases by 412.50% at a radial distance of 10 mm. Bubble break-up is the main reason for the generation of perforations within an air-induction nozzle, leading to early break-up of the spray sheet and the production of large spray droplets. Bubble break-up can be effectively controlled by modifying the nozzle configuration.