Variations In Water Content Research Articles

Modeling Water Flow in Variably Saturated Porous Soils and Alluvial Sediments

The sustainable exploitation of groundwater resources is a multifaceted and complex problem, which is controlled, among many other factors and processes, by water flow in porous soils and sediments. Modeling water flow in unsaturated, non-deformable porous media is commonly based on a partial differential equation, which translates the mass conservation principle into mathematical terms. Such an equation assumes that the variation of the volumetric water content (θ) in the medium is balanced by the net flux of water flow, i.e., the divergence of specific discharge, if source/sink terms are negligible. Specific discharge is in turn related to the matric potential (h), through the non-linear Darcy–Buckingham law. The resulting equation can be rewritten in different ways, in order to express it as a partial differential equation where a single physical quantity is considered to be a dependent variable. Namely, the most common instances are the Fokker–Planck Equation (for θ), and the Richards Equation (for h). The other two forms can be given for generalized matric flux potential (Φ) and for hydraulic conductivity (K). The latter two cases are shown to limit the non-linearity to multiplicative terms for an exponential K-to-h relationship. Different types of boundary conditions are examined for the four different formalisms. Moreover, remarks given on the physico-mathematical properties of the relationships between K, h, and θ could be useful for further theoretical and practical studies.

Climatic controls on leaf wax hydrogen isotope ratios in terrestrial and marine sediments along a hyperarid-to-humid gradient

Abstract. The hydrogen isotope composition of leaf wax biomarkers (δ2Hwax) is a valuable tool for reconstructing continental paleohydrology, since it serves as a proxy for the hydrogen isotope composition of precipitation (δ2Hpre). To yield robust palaeohydrological reconstructions using δ2Hwax in marine archives, it is necessary to examine the impacts of regional climate on δ2Hwax and assess the similarity between marine sedimentary δ2Hwax and the source of continental δ2Hwax. Here, we examined an aridity gradient from hyperarid to humid along the Chilean coast. We sampled sediments at the outlets of rivers draining into the Pacific as well as soils within catchments and marine surface sediments adjacent to the outlets of the studied rivers and analyzed the relationship between climatic variables and δ2Hwax values. We found that apparent fractionation between leaf waxes and source water is relatively constant in humid and semiarid regions (average: −121 ‰). However, it becomes less negative in hyperarid regions (average: −86 ‰) as a result of evapotranspirative processes affecting soil and leaf water 2H enrichment. We also observed that along strong aridity gradients, the 2H enrichment of δ2Hwax follows a non-linear relationship with water content and water flux variables, driven by strong soil evaporation and plant transpiration. Furthermore, our results indicate that δ2Hwax values in marine surface sediments largely reflect δ2Hwax values from the continent, confirming the robustness of marine δ2Hwax records for paleohydrological reconstructions along the Chilean margin. These findings also highlight the importance of considering the effects of hyperaridity in the interpretation of δ2Hwax values and pave the way for more quantitative paleohydrological reconstructions using δ2Hwax.

Effects of Pore Water Content on Stress Sensitivity of Tight Sandstone Oil Reservoirs: A Study of the Mahu Block (Xinjiang Province, China)

Traditional stress sensitivity experiments are typically conducted under dry conditions, without considering the reservoir’s water content. In reality, the presence of water within pores significantly influences the extent of stress sensitivity damage in tight sandstone oil formations, subsequently affecting the determination of stress sensitivity coefficients during experimentation. By investigating sandstone samples from wells in the Mahu Block of China’s Xinjiang province, we observed that increasing water saturation reduces the stress sensitivity of tight sandstone. By conducting stress sensitivity experiments under varying water content conditions, we found that the stress sensitivity coefficient is not a constant value but decreases as water saturation increases. Based on experimental comparisons, an optimized power-law model for stress-sensitive damage assessment was refined. By conducting stress-sensitive damage assessment experiments under different water content conditions and integrating the concept of comprehensive compression coefficient, an improved stress-sensitive power-law model was established allowing for the influence of water content. The accuracy of this improved model was increased by 46.98% compared to the original power-law model through experimental validation. The research outcomes can enhance the accuracy of permeability and productivity evaluation, providing valuable guidance for unconventional oil and gas development.

Spatiotemporal patterns of soil water replenishment and their seasonal origins in a subtropical red soil critical zone

Assessing the integration of precipitation and its isotopic signals in soil water is crucial for understanding the sensitivity of soil available water to precipitation variability. Here the investigations of water stable isotopes and in-situ soil water content were conducted for determining the spatiotemporal patterns of soil water replenishment and their seasonal origins in a subtropical red soil critical zone. Variations in soil water content provide valuable information regarding the quantity and depth of soil water replenishment in response to precipitation events. Soil water replenishment often penetrated to a depth of 100 cm or more from winter to early summer (from December to the next June), but the corresponding replenishment amounts were relatively low. However, most soil water replenishment events were generally limited to the upper 40 cm soil layers between midsummer and autumn (from July to November), with relatively large amounts in summer. The temporal and vertical variations in the seasonal origin index of soil water indicated that summer precipitation constituted the largest fractions (∼66 %) of soil water storage in the entire explored soil profile (thickness = 130 cm) during the study period. Winter precipitation was overrepresented in soil water only at the depth of 0–20 cm in spring, but it may vary slightly from year to year due to changes in winter precipitation patterns (amount and frequency). The findings of the current study broadly highlight how precipitation contributes to soil water storage over space and time, which has significant implications for plant water sources.

Water transfer mechanisms and vapor flow effects in seasonally frozen soils

In seasonally frozen soils, liquid water and water vapor movement are critical in numerous environmental and engineering areas. However, the process of soil water movement becomes complicated due to the coexistence of liquid water, water vapor, and ice, and the underlying mechanisms are not yet fully understood. Based on the theory of coupled water, vapor, and heat transport, the modified HYDRUS-1D freezing module was used to investigate the mechanisms of soil water transfer in a cold region. Compared with its previous version, the newly developed model overcomes the numerical instability caused by the phase transformation between liquid water and ice. The verification results showed that the modified model was numerically stable and highly accurate, indicating its suitability for the study region. The variations in soil temperature, water content, water storage, evaporation, and drainage displayed typical seasonal patterns during the analyzed period, reflecting the effects of freeze–thaw cycles and rainfall-infiltration processes. Liquid flow, driven by a water potential gradient, played a major role under most environmental conditions, except when the soil was frozen when it became negligible. In comparison, vapor flow, driven by a temperature gradient, dominated soil water flow when ice was present and accounted for a considerable proportion of the total water flux in dry conditions, proving its significance for affecting soil water transport. These results clarified the mechanisms of soil liquid water and water vapor transfers in seasonally frozen soils and provided more insights for deepening the hydrological cycle theory.

Study on spatiotemporal changes and influencing factors of frozen soil moisture during freeze-thaw period under different ecological construction measures in the loess plateau of China

The climatic conditions and soil characteristics of the Loess Plateau in China make it have a unique freeze–thaw process and the distribution of soil unfrozen water. In order to elucidate the spatio-temporal variation of soil unfrozen water during freeze–thaw period and its influencing factors under different ecological construction measures, The spatial and temporal variation of soil unfrozen moisture and its main influencing factors in five different ecological plots in the Loess Plateau during freeze–thaw period were studied by combining field monitoring and indoor calculation. The results showed that: (1) the spatiotemporal changes of unfrozen water content in soil were different under different vegetation restoration methods. The variation of unfrozen water content in fallow land was the largest at 20cm depth, while the variation in surface 10cm was the largest in the other four plots. (2) The average unfrozen water content of soil in the representative soil layer can be estimated more accurately, and the best representative soil layer in the five sample plots is concentrated in 20–30 cm. (3) During seasonal freeze–thaw period, the main controlling environmental factors of unfrozen water content are air temperature and surface temperature. The results can provide reference for soil protection and water resources management in northwest China, especially in the Loess Plateau.

Comparative responses of carbon flux components in recovering bare patches of degraded alpine meadow in the Source Zone of the Yellow River

The patchy degradation of alpine grasslands is a common phenomenon on the Qinghai-Tibetan Plateau, and the presence of bare patches (BP) in degraded grasslands significantly affects the functioning of the alpine meadow ecosystem. The succession of vegetation-recovered BP may lead to significant changes in ecosystem carbon (C) cycling. To date, it is unclear whether different components of net ecosystem carbon exchange (NEE) respond similarly or differently to the succession of recovering BP. Here, we conducted a field monitoring experiment in a degraded alpine meadow, and selected three successional stages for recovering BP to study the response of NEE and its components. We found that the succession of recoevering BP increased ecosystem respiration (ER) during the growing season and decreased ER during the off-growing season, with the differences in annual carbon output between different successional stages being insignificant. However, gross primary productivity increased with the successional gradient, and carbon input at the later stage of succession was significantly greater than that at the middle stage of succession. The succession of recovering BP promoted the carbon sequestration function of the alpine grassland, with the grassland acting as a carbon sink when it reached the state of healthy alpine meadow, while it acted as a carbon source during the middle stage of succession. Compared with BP, the amount of carbon sequested by healthy alpine meadows increased significantly by 219 g·C·m−2·yr−1. We also found that the responses of other components to the succession of recovering BP were inconsistent. In addition, the effects of succession of recovering BP on carbon flux were related to field-monitored variables (soil temperature and water content) and other considered variables (biomass, organic carbon, and microbial biomass carbon). These research findings highlight the importance of restoring vegetation in BPs, and are crucial for predicting the carbon balance in the future and formulating sustainable grassland management strategies.

Optimization of a Simple Analytical Workflow to Characterize the Phenolic Fraction from Grape Pomace

The recovery of polyphenols from grape pomace (GP) supports the promotion of sustainable bioeconomy. Accordingly, the development of pre-treatment and extraction techniques using low-solvent amounts and energy-efficient processes is highly desirable. In this work, a comprehensive strategy to maximize phenol extraction from two Umbrian red wine cultivars, Cabernet Sauvignon and Merlot, was proposed. Focus was paid to sample pre- (fresh, air-, oven- and freeze-dried pomace) and post-extraction (chemical- and enzymatic-hydrolysis) treatments. An experimental design was applied to optimize phenol recovery by ultrasound-assisted extraction: the variables water content in ethanol (20–80% v/v) and time (10–30 min) highlighted a critical influence on the total phenol content (TPC) selected as the response. β-glucuronidase hydrolysis provided the highest TPC and in vitro total antioxidant capacity also improving phenol identification and quantification via HPLC–DAD (particularly evident for freeze-dried Merlot and Cabernet GP, which gave a total phenolic content measured by HPLC equal to 1904.08 mg/g and 2064.64 mg/g, respectively). LC-HRMS/MS analysis allowed identity confirmation of the major phenols, and cytotoxicity assay highlighted the safety of the selected β-glucuronidase extracts towards Caco2 cell line. Ultimately, in the present work, we have addressed the importance of the recovery of bioactive compounds from grape pomace by proposing a comprehensive analytical strategy in which different methodological alternatives have been evaluated to preserve these compounds, in a frame of sustainability on a larger industrial scale.

Chemical Analysis of Chicken Sempol for Food Safety Program in Karanganyar Regency

This aims study to evaluate chemical composition of chicken sempol in Karanganyar Regency. The sampling location of the research was carried out at sempol A sellers (Karanganyar Square area), sempol B (Pujasera Streetfood area), sempol C (Jl. Lawu area). The research method used a Complete Randomized Design (RAL) with 3 treatments and 4 repeats. Sampling was carried out by nonprobability sampling and research method with descriptive quantitative analysis. Data analysis in this study used Analysis of Variance (ANOVA). The findings demonstrate significant (P<0.05) variations in protein content, water content, carbohydrate content, fat content and boraks and formalin analysis the chicken sempol. The highest chemical content of sempol is carbohydrate which is 51,12% in sempol A. The highest water content in sempol A (48.73%), the highest protein content in sempol C (10.76%), carbohydrate content A (51.12%), the highest fat content in sempol B (11.87%). Chemical quality tests reveal protein content at 9.59%, water content at 47.77%, carbohydrate content at 47.17%, fat content at 9.21%, the result and discussion of boraks and formalin on sempols is negative (-). Sempol ayam at traders in Karanganyar has different chemical characteristics. This study concludes that chicken sempol with chemical quality can provide information on the quality of food or processed products that are good for consumers so as to increase the nutritional value of food products. Keywords : chicken sempol ,chemical analysis, karanganyar regency, chemical characteristics, chemical composition

Characterization and prediction of compressive strength in ultralow-temperature frozen soil using nuclear magnetic resonance and WOA-ENN Model

Artificial ground freezing（AGF）has been utilized in a range of engineerings, including tunneling, shaft sinking, deep excavations, and the construction of underground structures. Currently, the strength and efficacy of artificial ground freezing technology have become a prominent subject of research. To reveal the trend of changes in the uniaxial compressive strength of ultralow-temperature frozen soil, uniaxial compression tests were carried out on soil samples with varying water contents (17 %, 20 %, and 23 %) and temperatures (-10 °C to −180 °C). To analyze the relationship between the unfrozen water content and compressive strength, the unfrozen water content in the frozen soil was quantitatively measured by nuclear magnetic resonance (NMR). Additionally, a prediction model for the compressive strength of ultralow-temperature frozen soil was built with an Elman neural network based on the whale optimization algorithm (WOA-ENN). The results indicate that the frozen soil exhibits elastic–plastic failure at temperatures above −80 °C and brittle failure at temperatures below −80 °C. In the temperature range from −10 °C to −80 °C, the compressive strength of the frozen soil increases linearly with decreasing temperature, and stabilizes at temperatures ranging from −80 °C to −180 °C. The turning point in compressive strength at −80 °C arises because the content of unfrozen water remains relatively constant below this temperature. Furthermore, the relationship between the unfrozen water content and compressive strength follows a power function. To predict the compressive strength of frozen soil at ultralow-temperatures, a WOA-ENN prediction model is proposed as it has a significantly lower average absolute percentage error (4.00 %) compared to the ENN prediction (24.49 %). Overall, the proposed prediction model effectively addresses the complex nonlinear relationship between the compressive strength of ultralow-temperature frozen soil and its influencing factors, thus providing valuable insights into the mechanical response of frozen soil under ultralow-temperature conditions.

Daily and seasonal patterns of stem diameter micro-variations in three semiarid forest species in relation to water status and environmental factors

Understanding the relationship between stem diameter micro-variation (SDMV) and stem water status and revealing the mechanism regulating stem water are essential for elucidating environmental adaptation and water use strategies in forest trees. Here, we report the results of the year-round monitoring (November 2018–October 2019) of SDMV and xylem sap flow obtained using high-resolution dendrometers and Granier-type thermal dissipation probes, respectively, in mature trees of three species in the semiarid Loess Plateau region: Quercus liaotungensis, Platycladus orientalis, and Robinia pseudoacacia. The year-round trend for the variations in stem diameter can be divided into phases of a decreasing period and a relatively stable period in the non-growing season, and a progressive rise and fluctuating plateau throughout the growing season. The observed interspecific differences in the time to full recovery from the water deficit state corresponded to species phenology and soil moisture conditions. These differences were manifested as the responses of sap flux density (Fd) and tree water deficit (TWD) to variations in soil water content during the growing season. Q. liaotungensis implements stomatal regulation early to avoid drastic water loss in the trunk, P. orientalis maintains a relatively stable Fd at the expense of increased TWD under soil drought, and R. pseudoacacia maintains relatively low stomatal conductance under soil drought with an increase in TWD. The results revealed that SDMV is determined by the stem water status and species-specific strategies for water use, which could provide beneficial information for forestation practices in semiarid regions.

Modeling the effect of slope aspect on temporal variation of soil water content and matric potential using different approaches by HYDRUS-1D

Slope aspect affects microclimate and soil moisture conditions, and thus has an important effect on the hydrological cycle. Given the lack of precise field data on this effect, two soil temperature, moisture and matric potential monitoring sites on north- and south-facing slopes have been established since 2017 in sandy loam soil under beech forest in a small valley near Ebergötzen, central Germany. HYDRUS-1D software was used with different approaches (including Rosetta, RETC, and RETC–measured θs approaches) for deriving soil hydraulic parameters of the van Genuchten model, to simulate temporal variability of soil water content and matric potential in the two slope aspects. Due to different microclimatic conditions, the south-facing slope was warmer and drier than the north-facing slope (two-years average temperatures 9.71 and 9.36 °C, and two-years average soil water contents 0.17 and 0.26 cm3 cm-3, respectively). The model was satisfactorily calibrated and validated on the two slopes. The calibration for the wet period was better on the south-facing slope (R2 = 0.772) than on the north-facing slope (R2 = 0.690). The simulation performance by HYDRUS-1D was better in the wet period than in the dry period. In the dry period, the model was better calibrated for the north-facing slope (R2 = 0.880) than for the south-facing slope (R2 = 0.691). The better calibration results for the wet period of south-facing slope can be explained by the location of the majority of measured soil water retention data which were in the near-saturation zone on the north-facing slope, and discontinuity of second-order derivative of the van Genuchten equation at saturation point when shape parameter (n) is smaller than 2. According to the model ability and different datasets used for the model validation, the north-facing plot was validated better than the south-facing plot for both wet and dry periods. Given that Rosetta was developed based on a soil hydraulic dataset from temperate climates, and the shortcomings of the hydraulic model, our results indicated that the Rosetta–derived approach was a reliable source for soil hydraulic parameters in both slope aspects for the wet period. However, the RETC–derived parameters were more accurate than Rosetta for the dry period on the north-facing slope.

Soil Moisture Distribution and Time Stability of Aerially Sown Shrubland in the Northeastern Margin of Tengger Desert (China)

Considering the importance of soil moisture in hydrological processes, it is crucial to understand the water distribution and time stability of different aerial shrub soils. There are few studies on the soil moisture of aerial vegetation in the northeastern margin of the Tengger Desert. Based on long-term monitoring data from the aerial seeding area in the northeastern margin of the Tengger Desert, the distribution characteristics of soil moisture and the temporal stability of soil moisture were studied. From June to October 2022, the soil moisture monitoring instrument WatchDog was used to monitor the long-term soil moisture changes (0–200 cm) in the four aerial afforestation plots of Hedysarum scoparium, mixed forest land (Hedysarum scoparium dominant species), mixed forest land (Calligonum mongolicum dominant species), and Calligonum mongolicum. The Spearman rank correlation coefficient was used to study the temporal stability of soil moisture in the four plots. Rainfall data were collected through small weather stations. The results show that the average soil water storage of four kinds of aerial shrub land in the study area was the highest in August, and the average soil water storage of different forest lands was different. The soil water content of the surface layer (0–30 cm) fluctuated the most in different months. The variation in soil water content in the shallow layer (30–100 cm) was smaller than that in the surface layer. The fluctuation of soil water content in the middle layer (100–150 cm) and deep layer (150–200 cm) was relatively stable. There was no strong variability in soil moisture content, and the temporal variation coefficient of surface soil moisture was the highest (31.44–39.8%), which showed moderate variability. The temporal variation coefficient of soil moisture in the shallow, middle and deep layers of all kinds of plots was significantly reduced, and the soil moisture stability of different aerial shrub land was the same. Spearman rank correlation analysis showed that the spatial pattern of soil water content in the surface layer (0–30 cm) and deep layer (150–200 cm) was more stable over time, that is, the temporal stability of soil water content was higher, and the temporal stability of soil water content in the middle and shallow layers of different types of shrub land was different. The research results help us to understand the soil hydrological process in the aerial seeding afforestation area in the northeastern margin of Tengger Desert, rationally arrange soil moisture monitoring points, efficiently manage and utilize water resources in the aerial seeding area, and provide a theoretical basis for local vegetation restoration and the optimization of the ecological environment.

Increased atmospheric moisture demand induced a reduction in the water content of boreal forest during the past three decades

Widespread forest mortality has been observed in recent years which may be related to the forest water content. Changes in atmospheric demand for water (vapour pressure deficit, VPD) and soil moisture due to climate change affect plants in terrestrial ecosystems. Hence, it is crucial to determine the impact of variations in soil-atmosphere water content on forest water content to enhance our predictive capability of future forest dynamics. Here, we explored the dynamics of forest water content in the boreal forest (BFC) based on remote sensing Ku-band vegetation optical depth (VOD) data and found a declining trend from 1988 to 2016. The study revealed a strong negative correlation between VPD and VOD and the negative trend of BFC water content increased with increasing annual VPD. Further analysis found a negative correlation between monthly transpiration and VOD, and a positive correlation between canopy conductance and VOD. The relationship exhibited greater significance in regions characterized by a more rapid increase in VPD suggesting elevated VPD led to a higher transpiration, resulting in a decline in forest water content and subsequent plant physiological regulation. This occurred consistently in intact and managed boreal forest, implying common climatic drivers on a large scale. The decrease of annual mean VOD was slower in the intact boreal forest than in the managed forest, which may be due to the diversity and richness of the intact forest. The findings enhanced the understanding of the dynamics of forest water content under atmospheric drought caused by climate change, which requires the adoption of strategies to prevent forest mortality.

Physiological characteristics of IRR 400 series rubber clones (Hevea brasiliensis Muell. Arg.) under drought stress

Background: Drought stress is one of the main causes of plant death. Strategies for plants survival are morphological adaptations, specific signaling pathways, and tolerance mechanisms. Rubber plantations have many uses, such as foreign exchange sources, job sources, forest revitalization, and a source of alternative wood for building materials and furniture. The rubber plant’s response to drought stress is a complex biological process. A tolerant rubber clone in a dry area is the right approach. The present study aimed to determine the mechanism of drought-tolerant clones, based on physiological characteristics, to obtain character selection and drought-tolerant clones early. Methods: The first factor examined for this work was clones (IRR 425, IRR 428, IRR 429, IRR 434, IRR 440, RRIC 100, and BPM 24) and the second factor was water content (30%, 60%, and 90%). The study was arranged on a factorial randomized block design and repeated three times. Characteristics observed were total sugar (µM), proline (mg/L), chlorophyll a, b, total (µg/mL), hydrogen peroxidase (µmol/g), ascorbate peroxidase (unit/mg), superoxide dismutase (unit/mg), and peroxide dismutase (unit/mg). Results: The tolerance ability of the IRR 400 series rubber clones to drought stress was determined by observing the characteristics of sugar total and proline. The concentration of total sugar and proline were higher when the plant was treated with a lower water content. The selected clones tolerant to drought stress are RR 425 and IR 434 with high total sugar content and proline. Other characteristics, namely chlorophyll a, b, and total, as well as hydrogen peroxidase, ascorbate peroxidase, super oxide dismutase, peroxide dismutase, cannot be used as selection characteristics for this study. Conclusions: This drought study of IRR 400 clones with varying water content percentages illustrated that the total sugar and proline characteristics could be used to distinguish tolerance levels from other observed characteristics.

Study on Spatiotemporal Transport Characteristics of Soil Moisture in Layered Heterogeneous Vadose Zone Based on HYDRAS-3D

The heterogeneity of layered soils affects the transport processes of water in the vadose zone. However, the mechanism of soil moisture transport in the vadose zone under heterogeneous media conditions, especially the three-dimensional transport mechanism, is a frontier problem to be studied. In order to reveal the law of soil water transport in the vadose zone under heterogeneous media, this paper constructs a three-dimensional model of water transport using HYDRAS-3D (V 2.x) software through in situ tests of water transport in 3 × 3 × 4 m sample and verifies and analyzes the model. The vertical distribution and variability of soil water content and the temporal and spatial rules of soil water transversal transport at the soil–layer interface were analyzed. The results indicate that after adjusting the parameters in the HYDRAS-3D model using measured values, the simulation results are reasonable, and the model has high reliability. To represent the water content variability characteristics of the test tube profile, water movement in the vadose zone was classified as follows: (I) steady period (April–September, less affected by rainfall), (II) slow change period (January–March), and (III) rainfall rapid change period (June, when the impact of rainfall on the test cylinder was greater). The two largest values of the soil water potential variation gradient, 19.9 and 17.8 cm/d, were observed in the silty clay layer of the test cylinder, and the influence of evaporation and infiltration in the silty clay layer was most notable at the interface. The lateral transport of soil water at the interface was influenced to a certain degree by the layered heterogeneity, wherein the fine sand layer exhibited the most pronounced impact. This was followed by silt and silty clay layers, with the silt layer showing the lowest degree of influence. The research results can provide scientific reference for the rational planning of water resources in the Yinchuan Plain.

Color calibration of moist soil images captured under irregular lighting conditions

Soil color is a valuable indicator that visually reflects soil properties. In the field of soil science, soil color has been widely used for soil identification and property assessment. Soil color is influenced not only by soil properties but also by lighting conditions; therefore, adequately considering the effect of lighting conditions for the color-based soil assessment is essential. This paper proposes a color calibration method for moist soil images captured under irregular lighting conditions. Four samples of weathered granite soil with varying water contents were captured under nine different lighting conditions. The effect of lighting conditions on the color of moist soil was analyzed using linear regression analysis in the CIELAB color space. The findings demonstrate a linear relationship between soil color and lighting conditions. Furthermore, the slopes of the linear regression equations remained consistent across all moist soil samples, irrespective of soil type and water content. Based on this, calibration equations were derived to adjust the color of moist soil images captured under arbitrary lighting conditions to those under the desired lighting conditions. The proposed method was validated using soil images captured under natural lighting conditions, which show high accuracy in color calibration except for cases with illuminance exceeding 70,000 lux. This color calibration method provides a reliable approach to evaluating soil properties through accurate color representation and presents new possibilities for developing digital image-based soil property prediction techniques that are less sensitive to lighting conditions.

Stability analysis of a slope containing water-sensitive mudstone considering different rainfall conditions at an open-pit mine

Mudstone, as a typical soft rock with wide distribution, has been endangering the slopes containing mudstone by its water-sensitivity of swelling and weakening strength when encountering water. To comprehensively understand the water-sensitivity of mudstone and reveal its influence on slope stability, we took the working slope containing water-sensitive mudstone of Shengli No.1 open-pit coal mine in Xilinhot, Inner Mongolia, China, as an example. Mudstone samples taken from the working slope were remodeled and saturated, and then triaxial tested to obtain the effective cohesion and effective internal friction angle. The filter paper method was used to obtain the soil–water characteristic curve of unsaturated mudstone. The pore structure of mudstone samples with different water contents were analyzed using the mercury intrusion porosimetry tests combined with the fractal dimension. The total pore content of the mudstone sample with lower water content is greater than that of the mudstone sample with higher water content. The mesopores are more in the mudstone sample with lower water content, while the small pores are more in the mudstone sample with higher water content. The variation of water content will change the complexity of mudstone pore structure. The higher the water content, the simpler the mudstone pore structure and the smoother the pore surface. Numerical calculations were conducted on the stability of the working slope under different rainfall conditions. The effective saturation on the mudstone layer surface changed and the plastic strain all occurred on the mudstone steps under different rainfall conditions. The key to preventing landslide of the slope containing water-sensitive mudstone in Shengli No.1 open-pit coal mine is to control the deformation and sliding of the mudstone layer.

Review of scientific instruments: Evaluation of adulteration in honey using a microwave planar resonator sensor.

A microwave microstrip line resonator sensor is developed as an alternative tool for detecting adulteration in honey. A honey-filled tube is placed at the position with the maximum electric field intensity. When the honey is adulterated, its permittivity is changed, leading to a distinct resonance frequency shift and enabling detection. Compared with the existing microwave sensors, this sensor offers the advantages of low cost, compact size, and easy fabrication. Moreover, quantitative analysis of the adulteration could be achieved. Electromagnetic simulation is performed using a co-simulation with CST and MATLAB. The simulation results reveal that the resonance frequency of the resonator decreases as the added water content increases, following a quadratic polynomial relationship. In the experiments, the results demonstrate a successive decrease in the resonance frequency from the empty tube, honey-filled tube to water-filled tube cases. Furthermore, honey samples with varying water contents (up to 70%) are tested, and the resonance frequency decreases with increasing added water content, which agrees well with the simulation results. In addition, there is a quadratic relationship between the two parameters. Principal component analysis is conducted on the transmission coefficients, and the first principal component decreases with increasing water content. With the addition of the second principal component, the cases of different water contents in honey can be well classified.

Estimating soil water content in a thorny forest ecosystem by time‐lapse electrical resistivity tomography (ERT) and HYDRUS 2D/3D simulations

AbstractDetermination of soil volumetric water content in forest ecosystems is particularly challenging due to deep rooting systems and unknown soil vertical and spatial heterogeneity. This research aims to test two undisturbed methods, electrical resistivity tomography (ERT) and HYDRUS 2D/3D, for 2D determination in a thorny forest ecosystem. The experiment consisted of infiltrating 10 L of water lasting 60 min. During infiltration, ERT measured apparent resistivity by time‐lapse measurements, and was measured with an FDR probe (EnviroSCAN) at 33, 63, 83, 97, and 163 cm depth close to the infiltration site. At the end of infiltration, a soil pit was dug, and 100 measurements of were performed with a TDR in a 10 × 10 cm regular grid. Archie law transformed soil resistivity (ERT) into using manual calibration, verified by an independent dataset. The 2D profile obtained by ERT was qualitatively compared with the HYDRUS 2D/3D one. HYDRUS 2D/3D was parametrized with calibrated parameters obtained with HYDRUS 1D using 106 days of obtained with EnviroSCAN. The results of HYDRUS 1D calibration and verification were satisfactory, with RMSE and Nash‐Sutcliffe coefficients ranging from 0.021 to 0.034 cm3 cm−3 and 0.11 to 0.77, respectively. The forward HYDRUS 2D/3D simulation disagrees with EnviroSCAN data for 33 cm depth. However, it follows the trend with near to zero variation of water content at 63 cm depth. Water content determination by ERT was satisfactory with RMSE for calibration and verification of 0.017 and 0.021 cm3 cm−3. HYDRUS 2D/3D and ERT comparisons were not equal, with a shallower wetting front by ERT and a deeper one for HYDRUS. Still, both wetting fronts agree with the wetting depth estimated by EnviroSCAN. We conclude that both methods are an alternative for determination in heterogeneous and deep soils of forest ecosystems.