Soil Moisture Characteristics Research Articles

Long-Term Characteristics of Surface Soil Moisture over the Tibetan Plateau and Its Response to Climate Change

Soil moisture over the Tibetan Plateau (TP) can affect hydrological cycles on local and remote scales through land–atmosphere interactions. However, TP long-term surface soil moisture characteristics and their response to climate change are still unclear. In this study, we firstly evaluate two satellite-based products—SSM/I (the Special Sensor Microwave Imagers) and ECV COMBINED (the Essential Climate Variable combined)—and three reanalysis products—ERA5-Land (the fifth generation of the land component of the European Centre for Medium-Range Weather Forecasts atmospheric reanalysis), MERRA2 (the second version of Modern-Era Retrospective Analysis for Research and Applications), and GLDAS Noah (the Noah land surface model driven by Global Land Data Assimilation System)—against two in situ observation networks. SSM/I and GLDAS Noah outperform the other soil moisture products, followed by MERRA2 and ECV COMBINED, and ERA5-Land has a certain degree of uncertainty in evaluating TP surface soil moisture. Analysis of long-term soil moisture characteristics during 1988–2008 shows that annual and seasonal mean soil moisture have similar spatial distributions of soil moisture decreasing from southeast to northwest. Additionally, a significant increasing trend of soil moisture is found in most of the TP region. With a non-linear machine learning method, we quantify the contribution of each climatic variable to warm-season soil moisture. It indicates that precipitation dominates soil moisture changes rather than air temperature. Pixel-wise partial correlation coefficients further show that there are significant positive correlations between precipitation and soil moisture over most of the TP region. The results of this study will help to understand the role of TP soil moisture in land–atmosphere coupling and hydrological cycles under climate change.

The Characterization of the Vertical Distribution of Surface Soil Moisture Using ISMN Multilayer In Situ Data and Their Comparison with SMOS and SMAP Soil Moisture Products

In this paper, we investigated the vertical distribution characteristics of surface soil moisture based on ISMN (International Soil Moisture Network) multilayer in situ data (5, 10, and 20 cm; 2, 4, and 8 in) and performed comparisons between the in situ data and four microwave satellite remote sensing products (SMOS L2, SMOS-IC, SMAP L2, and SMAP L4). The results showed that the mean soil moisture difference between layers can be −0.042~−0.024 (for the centimeter group)/−0.067~−0.044 (for the inch group) m3/m3 in negative terms and 0.020~0.028 (for the centimeter group)/0.036~0.040 (for the inch group) m3/m3 in positive terms. The surface soil moisture was found to have very significant stratification characteristics, and the interlayer difference was close to or beyond the SMOS and SMAP 0.04 m3/m3 nominal retrieval accuracy. Comparisons revealed that the satellite retrievals had a higher correlation with the field measurements of 5 cm/2 in, and SMAP L4 had the smallest difference with the in situ data. The mean difference caused by using 10 cm/4 in and 20 cm/8 in in situ data instead of the 5 cm/2 in data could be about −0.019~−0.018/−0.18~−0.015 m3/m3 and −0.026~−0.023/−0.043~−0.039 m3/m3, respectively, meaning that there would be a potential depth mismatch in the data validation.

Estimation of the soil hydraulic properties and parameter characteristics of Benggang erosion in granite in southern China

AbstractBenggang is an erosional landform that forms in granite hills due to coupled hydraulic and gravity erosion, and its unique development makes it difficult to obtain moisture characteristics through direct means. In this study, the soil moisture characteristics were investigated on the collapsing walls with different weathering degrees of two different Benggang types defined as scoop‐shaped Benggang and strip‐shaped Benggang in the typical Benggang erosion areas of southeastern Guangxi. The soil water characteristic curves (SWCCs) of the collapsing wall were measured by the centrifuge method to explore the moisture transport mechanism of Benggang development. The response of moisture characteristics to the Benggang morphology was not significant, but the soil layer changes in the collapsing wall had a significant impact. The Atterberg limits of the surface layer and laterite layer were significantly higher than those of the transition layer and sandy layer, with a liquid limit (LL) value exceeding 55%, indicating high LL clay. The Van Genuchten (VG), Gardner and Fredlund–Xing (FX) models were used to fit the SWCCs, and the results indicated that the VG model had a high fitting accuracy (R2 > 0.984), followed by the FX model (R2 > 0.943); however, the Gardner model had a low fitting accuracy (R2 > 0.891). With the change in matrix suction, the sandy layer had the maximum water release capacity, followed by the transition layer, and finally the surface layer and laterite layer. The variation in equivalent pore size distributions with soil layers showed that the micropores in the laterite layer of the two Benggangs accounted for 44.91% and 44.38% of the total porosity. The macropores of the sandy layer accounted for 35.40% and 36.84% of the total porosity. Both the unsaturated hydraulic conductivity K(θ) and water diffusivity D(θ) exhibited two abrupt changes with increasing soil volumetric water content, and K(θ) and D(θ) of the lower layers were larger than those of the upper layers. The heterogeneity of soil texture and pore conditions among different collapsing wall soil layers can significantly affect the Benggang water conditions. This study provides a database for further investigation of the Benggang development mechanism.

Response of soil moisture and water use efficiency to straw mulching amount and mulching period in black soil zone of northeast China

To reveal the mechanisms of straw mulching amounts and mulching periods on soil moisture in the black soil zone of Northeast China. Three types of straw mulching (0.4, 0.8, and 1.2 kg/m2) and two mulching periods (sowing stage and three-leaf stage) were set up as interactive experiments, and no straw mulching was used as the control (CK) to analyze the response mechanisms of soil moisture content, water consumption, and water use efficiency to straw mulching periods and mulching amounts at different depths. The results showed that straw mulching improved the moisture storage capacity compared with no straw mulching, and the straw mulching rate of 0.8 kg/m2 at the three-leaf stage improved the moisture storage capacity and reduced the water consumption capacity compared with the straw mulching at the sowing stage, CK and other straw mulching treatments at the three-leaf stage; the crop yield and water use efficiency increased and then decreased with the increase of straw mulching. The increase of crop yield and water use efficiency under the straw mulching treatments at the three-leaf stage was higher than that under the same straw mulching treatments at the sowing stage. The analysis of the dual effects of straw mulching amounts and mulching periods on moisture gain and loss showed that the straw mulching amounts of 0.8 kg/m2 at the three-leaf stage had the best effect on soil moisture characteristics and water use efficiency.

Discrimination and mapping ground surface freeze and thaw states over Northeastern China based on the improved dual-index algorithm

Accurate delineation of spatiotemporal variations in ground surface soil freeze and thaw (F/T) states is essential to appraise many geoscience issues, such as the hydrological circulation and land surface-atmosphere feedbacks. Recently, an Improved Dual-index algorithm (DIA) method was proposed by accounting for the influence of soil moisture variations on the discrimination accuracy with passive microwave remote sensing (RS) data products. Compared with the original DIA, the Improved DIA method has proven to be a more practical approach on surface soil F/T states discrimination. However, the method has only been applied and verified in cold regions of high-altitude (e.g., Tibetan Plateau), it's applicability and effectiveness in the cold areas in mid-high latitudes, where the geographic and climatic conditions are quite different, yet remained to be further explored. The present study investigated the feasibility of using AMSR-E (the Advanced Microwave Scanning Radiometer-EOS) and AMSR2 (the second Advance Microwave Scanning Radiometer) passive microwave RS data products to discriminate the F/T states of the ground surface for a long period from 2002 to 2019 by means of the Improved DIA method over a typical mid-high latitude cold region of Northeastern China. Seasonal variation characteristics of soil moisture in mid-high latitude areas were similar with those in high-altitude areas, even though the spatial heterogeneity of soil water content was significant in different regions. Discriminating surface soil F/T states with the Improved DIA method derived overall discriminating accuracy of about 91.6% in the study area, which demonstrated excellent feasibility of the Improved DIA method in mid-high latitude cold regions. The mapping results shown surface soil F/T cycle in Northeastern China responding to climate change was examined from the perspective of regional average, both the proportion of frozen soil area and frozen days showed significant decreasing trends continuously with differed quite spatially. The discriminating accuracy of the Improved DIA method was found to be lower in plain areas with dense populations and large farmland areas compared to mountainous areas when human activities were not taken into consideration, as quantifying human activities can be challenging. The Improved DIA method has been well verified in both high-altitude and high-latitude regions; it has great potential in global scale research.

Preferential flow influences the temporal stability of soil moisture in a headwater catchment

The dynamics and controls of soil moisture spatial organization are crucial to modeling water flux and land–atmosphere interactions across landscapes. Despite this importance, the control of subsurface preferential flow on the temporal stability of soil moisture spatial organization (TSSS) has not been thoroughly examined. This study monitored daily soil moisture at multiple depths (5–162 cm) for three consecutive years at 33 sites across a forested headwater catchment spanning 7.9 ha. The standard deviation of the relative difference in soil moisture between each monitoring location and the catchment mean (i.e., SDRD, a measure of TSSS) was calculated to quantify the influence of controlling factors on TSSS. Factors considered included soil moisture monitoring frequency, soil and terrain attributes, soil wetness condition, and preferential flow. The analysis was conducted separately for wet and dry seasons. The results indicated that (1) soil moisture monitoring frequency had a considerable impact on TSSS, particularly in valley and swales during dry seasons. As the monitoring frequency increased from 1 day to 28 days, the SDRD values of areas with varied soil–terrain attributes all decreased, suggesting a more stable TSSS. However, this also implied that coarser monitoring frequencies might not capture short-term (e.g., daily) soil moisture processes and associated TSSS dynamics. (2) The relationship between soil–terrain attributes and TSSS was stronger during dry seasons than wet seasons (R2 of 0.597 vs. 0.301, P < 0.05). (3) TSSS was significantly correlated with preferential flow frequency (r = 0.611, P < 0.05) at the study catchment. Including preferential flow frequency as a regression variable improved the explanation and prediction of TSSS. This study confirms the vital role of preferential flow in regulating TSSS in complex terrain. These findings underscore the need for high-frequency monitoring to accurately characterize soil moisture distributions over time and space in similar environments.

Retracted: Spatial-Temporal Variation Characteristics of Soil Moisture and Nutrients Based on Nanomaterials in the Root Zone of Haloxylon ammodendron Seedlings

Retracted: Spatial-Temporal Variation Characteristics of Soil Moisture and Nutrients Based on Nanomaterials in the Root Zone of Haloxylon ammodendron Seedlings

Evaluation of Remote Sensing and Reanalysis Products for Global Soil Moisture Characteristics

Soil moisture (SM) exists at the land-atmosphere interface and serves as a key driving variable that affects global water balance and vegetation growth. Its importance in climate and earth system studies necessitates a comprehensive evaluation and comparison of mainstream global remote sensing/reanalysis SM products. In this study, we conducted a thorough verification of ten global remote sensing/reanalysis SM products: SMAP DCA, SMAP SCA-H, SMAP SCA-V, SMAP-IB, SMOS IC, SMOS L3, LPRM_C1, LPRM_C2, LPRM_X, and ERA5-Land. The verification was based on ground observation data from the International SM Network (ISMN), considering both static factors (such as climate zone, land cover type, and soil type) and dynamic factors (including SM, leaf area index, and land surface temperature). Our goal was to assess the accuracy and applicability of these products. We analyzed the spatial and temporal distribution characteristics of global SM and discussed the vegetation effect on SM products. Additionally, we examined the global high-frequency fluctuations in the SMAP L-VOD product, along with their correlation with the normalized difference vegetation index, leaf area index, and vegetation water content. Our findings revealed that product quality was higher in regions located in tropical and arid zones, closed shrubs, loose rocky soil, and gray soil with low soil moisture, low leaf area index, and high average land surface temperature. Among the evaluated products, SMAP-IB, SMAP DCA, SMAP SCA-H, SMAP SCA-V, and ERA5-Land consistently performed better, demonstrating a good ability to capture the spatial and temporal variations in SM and showing a correlation of approximately 0.60 with ISMN. SMOS IC and SMOS L3 followed in performance, while LPRM_C1, LPRM_C2, and LPRM_X exhibited relatively poor results in SM inversion. These findings serve as a valuable reference for improving satellite/reanalysis SM products and conducting global-scale SM studies.

Strategy for Deriving Sacramento Model Parameters Using Soil Properties to Improve Its Runoff Simulation Performances

Physically-based parameter estimations are essential to improve the simulation performance of a hydrologic model and to produce physically reasonable parameters with spatial consistency. This study proposed a parameter derivation strategy to improve the Sacramento Soil Moisture Accounting (SAC-SMA) model simulation performance based on the publicly accessible Harmonized World Soil Database (HWSD). The HWSD soil properties were used to estimate the soil moisture characteristics, and the HWSD soil texture classifications and International Geosphere-Biosphere Programme (IGBP) land cover types were used to identify the Soil Conservation Service (SCS) runoff curve number (CN). After the soil moisture characteristics and CNs were identified, the major parameters of the SAC-SMA model were derived. The simulation results were evaluated using the Nash efficiency coefficient (NSEC), and Free Search (FS) algorithm was used to further adjust and calibrate the parameters. Compared with the simulation accuracy (NSEC = 0.66~0.88) and parameter transferability (NSEC = 0.22~0.83) obtained for the SAC-SMA model using directly calibrated parameters, the HWSD data-derived parameters allowed the SAC-SMA model to achieve a similar simulation accuracy (NSEC = 0.65~0.86) and a better transferability (NSEC = 0.61~0.85).

Performance analyses of effective rainfall estimation methods for accurate quantification of agricultural water footprint

Water footprint (WF) assessments have become a significant tool for the sustainable management in recent years. Effective rainfall (Peff) is a critical indicator for characterizing soil moisture (green water, WFgreen) and calculating irrigation requirements (blue water, WFblue). However, majority of the water footprint analyses employ empirical or numerical models to predict Peff, and the number of studies for experimental validation of these models are quite insufficient. The main scope of this study is to test the performance of commonly used Peff estimation models in relation to the soil water balance (SWB) of an experimental site. Accordingly, the daily and monthly soil water budget is estimated from a maize field which is characterized as semi-arid land with continental climate (Ankara, Turkey), equipped with moisture sensors. Then, Peff, WFgreen, and WFblue parameters are calculated using FP, US-BR, USDA-SCS, FAO/AGLW, CROPWAT, and SuET methods and compared with SWB method. Employed models were highly variable. CROPWAT and US-BR predictions were the most accurate. In majority of months, the CROPWAT method estimated the Peff with a maximum deviation of 5% from the SWB method. In addition, the CROPWAT method predicted blue WF with an error less than 1%. The widely utilized USDA-SCS approach did not produce expected results. The FAO-AGLW method provided the lowest performance for each parameter. We also find that the errors in estimating Peff in semi-arid conditions cause green and blue WF outputs to be quite less accurate than the dry and humid cases. This study provides one of the most detailed assessments about the impact of effective rainfall on the blue and green WF results with high temporal resolution. The findings of this study are important for the accuracy and performance of the formulae used in Peff estimations and to develop more precise blue and green WF analyses in the future.

Construction of a Time-Variant Integrated Drought Index Based on the GAMLSS Approach and Copula Function

Construction of an integrated drought index is a fundamental task to conducting drought disaster risk management and developing drought resistance planning strategies. Given the evident non-consistent features during the drought evolution process, firstly, the GAMLSS approach was utilized to construct multiple combination scenarios of time-variant parameters and corresponding probability distribution functions. Then, the time-variant comprehensive drought index integrating the variable characteristics of precipitation and soil moisture was established by means of the copula function. Finally, the reliability of the time-variant comprehensive drought index was verified through its application in frequency analysis and return period determination of drought hazard system in Huaibei Plain, China. The application results demonstrated that: (1) The variation of the time-variant integrated drought indicator presented strong consistency with both soil moisture and precipitation during historical years in Huaibei Plain. (2) The overall variation of the drought hazard system characterized by drought duration and severity presented a gradual mitigation trend from west to east and north to south in Huaibei Plain, which agrees with the geographic differences and water resources availability distribution features. (3) Drought recognition results, including the frequency of drought events and typical drought processes with extreme grades, are in agreement with the practical statistics and observed data series. On the whole, the proposed time-variant integrated drought indicator is capable of extracting complex variation characteristics within the drought hazard evolution process, and can be further applied in drought monitoring, recognition and assessment research fields.

Spatiotemporal variability and driving factors of the shallow soil moisture in North China during the past 31 years

To fully understand the dynamic change characteristics of soil moisture in North China, the spatiotemporal patterns of soil moisture anomalies (SMA) in the four active soil layers from January 1990 to December 2020 are analyzed based on the Global Land Data Assimilation System (GLDAS) model, then the driving factors and corresponding contribution rates (CRs) for SMA change are determined together with the meteorological, socioeconomic and land cover data. The results show that the SMA in the last three layers present decreasing trends, and the trend magnitudes increase in multiples with the increase of soil depth. The area with the most severe soil dry is clustered in the east-central plain, while the relatively wet areas are scattered in western Shanxi and northern Hebei. The annual, intra- and inter-annual cycles (1.0, 0.5, 4.3 and 7.3 yr) are the dominant frequency of the SMA time series, which are driven jointly by 6 natural-type factors and 6 human-type factors, especially the intensified evaporation and dramatically expanding urbanization. By combining principal component analysis (PCA) and grey absolute correlation degree, the reintegrated human and natural factors respectively account for 49.46% and 50.54% of mean CRs to SMA in the four layers, but the human factor dominates the change of the bottom SMA. On the other hand, the determined mean CRs by combining exploratory factor analysis (EFA) and grey absolute correlation degree are 53.46% and 46.44% for reintegrated positive and negative factors, but the negative factor has a greater effect on the bottom SMA. The results provide a clear clarification of the soil moisture dynamic change, which is conducive to shedding new light on water resources management, agricultural security and ecological sustainability.

Study on Soil Moisture Characteristics in Southern China Karst Plant Community Structure Types

An understanding of soil moisture variation patterns under different plant community structures is crucial for the restoration of vegetation in southern China karst regions. Therefore, four plant community structure types: arbor + herb (AH), shrub + herb (SH), arbor + shrub + herb (ASH), and herb (H), were selected as the research objects. A soil moisture sensor was used to monitor the soil moisture content in the 0–70 cm soil layer, to analyze the variation characteristics of soil moisture content and to explore the differences under different plant community structure types. The results indicate that: (1) A total of 31 plant species in 31 genera and 18 families were recorded, among which herbs were the most abundant. There were significant differences in diversity indexes for ASH and H. The differences between Shannon–Wiener index and Simpson index of AH and H were significant, and between AH and SH in Pielou index and Simpson index were statistically significant. The Pielou index between SH and H was significantly different. (2) There were significant differences in soil water content among the four plant community types, showing SH &gt; AH &gt; H &gt; ASH. The variation of soil moisture was consistent with the trend of rainfall, with the surface soil moisture more sensitive to rainfall events, and the deeper soil moisture had a lag. The Shannon–Wiener index was significantly and positively correlated with the Simpson index and the Margalef index. There was a highly significant positive correlation between Margalef index and Simpson index. The 20–30 cm soil layer was highly negatively correlated with the Margalef index and significantly and negatively correlated with the Shannon–Wiener index and the Simpson index. (3) The response of soil moisture of plant community structure types to light rain event was not obvious. The growth rates of soil water content in the 30–50 and 50–70 cm layers of the SH were higher in moderate rain event than that in heavy rain event, and H, AH, and ASH had larger growth rates in heavy rain events. The results provide a reference for the effective utilization of soil and water resources and the restoration of vegetation, as well as for plant community structure configuration decisions in the southern China karst region.

BAG: A Linear-Nonlinear Hybrid Time Series Prediction Model for Soil Moisture

Soil moisture time series data are usually nonlinear in nature and are influenced by multiple environmental factors. The traditional autoregressive integrated moving average (ARIMA) method has high prediction accuracy but is only suitable for linear problems and only predicts data with a single column of time series. The gated recurrent unit neural network (GRU) can achieve the prediction of time series and nonlinear multivariate data, but a single nonlinear model does not yield optimal results. Therefore, a hybrid time series prediction model, BAG, combining linear and nonlinear characteristics of soil moisture, is proposed in this paper to achieve the identification process of linear and nonlinear relationships in soil moisture data so as to improve the accuracy of prediction results. In BAG, block Hankel tensor ARIMA (BHT-ARIMA) and GRU are selected to extract the linear and nonlinear features of soil moisture data, respectively. BHT-ARIMA is applied to predict the linear part of the soil moisture, and GRU is used to predict the residual series, which is the nonlinear part, and the superposition of the two predicted results is the final prediction result. The performance of the proposed model on five real datasets was evaluated. The results of the experiments show that BAG has a higher prediction accuracy compared with other prediction models for different amounts of data and different numbers of environmental factors.

Response characteristics of soil moisture to rainfall for a single grass type in an urban area

Abstract Urbanization significantly impacts hydrological processes and the water environment in the urban area. Studies on soil moisture are necessary to explore the hydrological characteristics against the background of urbanization. A regional grassland with Bermudagrass in Yangzhou City, China, was adopted as the study area. An analysis of its response characteristics to rainfall infiltration was carried out for different rainfall events. The Penman–Monteith equation was used to estimate the hourly evapotranspiration (ET) of the soil layers at depths of 0–30 cm and 0–10 cm. The results indicate that the response time of the soil water content in the root layer (0–10 cm) decreases with the decrease of the soil water content in the topsoil. The rate of the increase of the soil water content increases as the rainfall intensity increases in the state of unsaturation. The soil water in the root layer provided more than 70% of the total ET. The Nash efficiency coefficient of the simulation results of the soil water content at different depths obtained using the Hydrus-1D model was more than 0.75. The rationality of the results for the different rainfall events and the infiltration depth were verified via numerical simulations using the Hydrus-1D model.

Spatiotemporal variability of soil moisture over Ethiopia and its teleconnections with remote and local drivers

Soil moisture is one of the essential climate variables with a potential impact on local climate variability. Despite the importance of soil moisture, studies on soil moisture characteristics in Ethiopia are less documented. In this study, the spatiotemporal variability of Ethiopian soil moisture (SM) has been characterized, and its local and remote influential driving factors are investigated. An empirical orthogonal function (EOF) and KMeans clustering algorithm have been employed to classify the large domain into homogeneous zones. Complex maximum covariance analysis (CMCA) is applied to evaluate the covariability between SM and selected local and remote variables such as rainfall (RF), evapotranspiration (ET), and sea surface temperature (SST). Inter-comparison among SM datasets highlight that the FLDAS dataset better depicts the country’s SM spatial and temporal distribution (i.e., a correlation coefficient r=0.95\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r=0.95$$\\end{document}, rmsd=0.04m3m-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$rmsd=0.04{\\mathrm{m}}^{3}{\\mathrm{m}}^{-3}$$\\end{document} with observations). Results also indicate that regions located in northeastern Ethiopia are drier irrespective of the season (JJAS, MAM, and OND) considered. In contrast, the western part of the country consistently depicted a wetter condition in all seasons. During summer (JJAS), the soil moisture variability is characterized by a strong east–west spatial contrast. The highest and lowest soil moisture values were observed across the country’s central western and eastern parts, respectively. Furthermore, analyses indicate that interannual variability of SM is dictated substantially by RF, though the impact on some regions is weaker. It is also found that ET likely drives the SM in the eastern part of Ethiopia due to a higher atmospheric moisture demand that ultimately invokes changes in surface humidity and rainfall. A composite analysis based on the extreme five wettest and driest SM years revealed a similar spatial distribution of wet SM with positive anomalies of RF across the country and ET over the southern regions. Remote SSTs are also found to have a significant influence on SM distribution. In particular, equatorial central Pacific and western Indian oceans SST anomalies are predominant factors for spatiotemporal SM variations over the country. Major global oceanic indices: Oceanic Nino Index (ONI), Indian Ocean Dipole (IOD), Pacific warm pool (PACWARMPOOL), and Pacific Decadal Oscillations (PDO) are found to be closely associated with the SM anomalies in various parts of the country. The associationship between these remote SST anomalies and local soil moisture is via large-scale atmospheric circulations that are linked to regional factors such as precipitation and temperature anomalies.

三峡库区典型茶园土壤水分对不同降雨模式的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 三峡库区典型茶园土壤水分对不同降雨模式的响应 DOI: 10.5846/stxb202201240232 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42077065）；国家自然科学基金项目（U224022） Response of soil moisture in typical tea gardens to different rainfall regimes in the Three Gorges Reservoir Area Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤水分是坡面产流和生物地球化学过程的关键控制因素。降水事件可以通过引起土壤剖面不同深度的土壤水分响应，从而影响流域中的径流路径、产流机制和土壤侵蚀过程等。基于三峡库区典型分布的茶园为对象，通过长期定点、高频的气象和水分数据观测，研究不同降雨模式下茶园不同土层深度（0-10、10-20、20-30、30-40cm）土壤水分的时空变化特征，分析茶园不同深度土壤在雨季的水分动态变化规律和对不同降雨模式的响应特征。结果表明：（1）研究区内的降雨和土壤水分含量均表现出明显的季节性特征。降雨在7月达到最大值，土壤水分含量则在8月达到峰值。表明降雨是影响土壤水分含量变化的重要因子，土壤水分对降雨有着明显的响应过程。（2）在相同降雨条件下，土壤含水量具有明显的垂直梯度变化。随着土层深度的增加，土壤水分对降雨的响应逐渐呈现出滞后现象。表层土壤（0-20cm）对降雨的响应较为迅速且幅度更加明显，深层土壤（30-40cm）水分含量变化相对稳定，并且对降雨的响应时间更加滞缓。随着土层深度的增加，土壤水分含量的变化幅度逐渐趋于平稳。（3）土壤水分含量对不同的降雨模式表现出显著差异。在较大雨强条件下，土壤水分变化出现了上升期、平台期及退水期。在小雨强短历时的降雨中，降雨对土壤水分的影响主要表现在土壤表层（0-10cm）。在降雨初期，降雨强度越大，土壤水分入渗越快，土壤的响应深度越深。研究三峡库区典型分布的茶园在不同降雨模式下的土壤水分变化特征，为三峡库区坡地的降水资源优化配置和园地面源污染防控提供理论依据，对区域水土流失治理以及面源污染物防控具有重要意义。 Abstract:Soil moisture is a key control factor for slope runoff generation and biogeochemical processes. Rainfall events can affect runoff paths, runoff mechanisms, and soil erosion processes in watersheds by causing soil moisture responses at different depths in the soil profile. Based on the typical tea gardens in the Three Gorges Reservoir Area, through long-term, fixed-point and high-frequency meteorological and moisture data observations, the temporal and spatial variation characteristics of soil moisture in different soil depths (0-10, 10-20, 20-30 and 30-40cm) of tea gardens under different rainfall regimes was studied, and the dynamic variation of soil moisture in the rainy season at different depths of tea gardens and the response characteristics to different rainfall regimes were analyzed. The results showed that:(1) The rainfall and soil moisture content in the study area showed obvious seasonal characteristics. Rainfall peaked in July and soil moisture levels peaked in August. It showed that rainfall was an important factor affecting the change of soil moisture content, and soil moisture had an obvious response process to rainfall. (2) Under the same rainfall conditions, soil water content had obvious vertical gradient changes. With the increase of soil depth, the response of soil moisture to rainfall gradually showed a hysteresis phenomenon. The topsoil (0-20cm) responds to rainfall more rapidly and the amplitude was more obvious, the change of water content in the deep soil (30-40cm) was relatively stable, and the response time to rainfall was more sluggish. With the increase of soil depth, the variation range of soil moisture content gradually became stable. (3) The soil moisture content showed significant differences with different rainfall regimes. Under the condition of high rainfall intensity, soil moisture changes appeared in the rising period, the plateau period and the retreating period. In the rainfall with small rainfall intensity and short duration, the effect of rainfall on soil moisture was mainly manifested in the soil surface layer (0-10cm). The greater the rainfall intensity, the faster the soil moisture infiltration, and the deeper the soil response depth were exhibited in the early stage of rainfall. Studying the characteristics of soil moisture variation characteristics in typical tea gardens in the Three Gorges Reservoir area under different rainfall patterns will provide a theoretical basis for the optimal allocation of precipitation resources and the prevention and controlling of ground source pollution in the gardens, which is of great significance to regional soil erosion control and the prevention and control of non-point source pollution. 参考文献 相似文献 引证文献

Fluctation moisture properties in the application of soil dielectric measurement in the North Bengkulu District, Indonesia

Information about soil moisture in the root layer is very important in evaluating water availability for plants, erosion rates and various other hydrological characteristics. Previous research has found a technology for measuring soil dielectric properties as a soil moisture estimator that can be carried out quickly in the field. The purpose of this study was to apply dielectricity technology in estimating the characteristics of soil moisture in situ in the field at the North Bengkulu in Bengkulu Province. Five land units in North Bengkulu Regency, Indonesia, have been selected as experimental sites. At each location, the soil profile was excavated to a depth of 100 cm, the basic characteristics of the soil in each layer were described in the field and analyzed in detail in the laboratory. The variables measured in the field are the measurement of the dielectric properties of the soil, the effective depth of the soil, the horizon and the characteristics of each horizon. The variables analyzed in the laboratory were texture, organic matter in each layer, aggregate stability at 0-10 cm layer, field soil moisture at the time of measurement, and groundwater characteristics. The relationship between the data on the basic characteristics of the soil with the soil moisture balance variable in the laboratory analysis and measurements of dielectric properties in the field, was then determined using regression analysis. The results showed that the five locations studied had different profile characteristics and groundwater fluctuations. Of the four independent variables tested (percentage of sand, silt, clay and organic carbon) then the content of sand and clay can be used as predictors of the water content of field capacity. Because the four independent variables have a very weak correlation with permanent wilting point water, the available water content can only be predicted from the sand and clay content.

Development Of Equation Of Curve To Estimate Volumetric Soil Moisture Content In CaseOf Tensiometer To Overcome The Moisture Measurement Error Due To Time Lag Issues

A field experiment was carried out at the Instructional Farm of Bidhan Chandra krishi viswavidyalaya, located in Mohanpur, Nadia, West Bengal, in order to explore the variations in estimation of soil moisture due to time lag issues in case of tensiometer. In this work, the gravimetric technique and tensiometers were used to calculate the volumetric soil moisture content. With regard to the gravimetric approach, which was considered as the reference method, the variation of volumetric soil moisture content derived from tensiometer was analysed. For the tensiometer, it was calculated that the coefficient of variation (CV) and standard deviation (STD) values were 0.213 and 6.95 respectively. The tensiometer data was processed to compare with that volumetric moisture data which was obtained via the gravimetric approach. The objective of this study is to generate an equation of curve which would estimate the actual (error-free) volumetric soil moisture content for tensiometer from the measured volumetric soil moisture content. The equation of the curve, y = 0.009x2 + 0.7786x + 7.0652, was generated by plotting volumetric soil moisture content under tensiometer against volumetric soil moisture measured by gravimetric method (observed data). As tensiometer is not capable of producingcorrect moisture values from known tension values using soil moisture characteristics curves, due to time lag issues, soin determining the correct soil moisture status, the method of development of the equation is necessary and was proved to be very much fruitful whenever this instrument was used in the field.

Effect of Moisture Absorbent Hydro Polymer on Growth of Nursery Coconut Seedlings in Sri Lanka

Coconut palm is one of the most important plantation crops in the world. Selecting the best planting materials for field planting assures higher productivity. Cost of production of coconut seedling is very high in coconut nurseries, because as coir dust is becoming scarce even within the Coconut Triangle. The use of coir dust in the potting mixture might not be feasible in the near future. Therefore, it is important to test the suitability of other options available for replacing coir dust. Moisture absorbent hydro polymer (Zeba) is one of the best alternatives to be used instead of coir dust in potting media of coconut seedlings. Thus, this experiment was conducted to investigate the effect of moisture absorbent hydro polymer on growth of coconut seedlings and water retention characteristics of the growth media.&#x0D; The experiment was carried in a plant house and the laboratory at the Agronomy Division, Coconut Research Institute of Sri Lanka (CRI), Lunuwila. The treatments were laid according to Completely. Randomized Design (CRD) with twelve replicates. Different potting mixtures were used as treatments. Growth parameters of the seedlings and the moisture parameters of the growth media; moisture content and the water holding capacity were measured and analyzed.&#x0D; There was no significant difference (P&gt;0.05) between the tested treatments in seedling girth and root volume. The results revealed that there were significant (P&lt;0.05) differences between the treatments on seedling height, number of fully opened leaves, leaf area, dry shoot weight, dry root weight, soil moisture content and soil water retention capacity. The highest plant growth rate was recorded in T1 • There were significant (P&lt;0.05) differences between the treatments on number of fully opened leaves at 10th and 12th weeks after planting. T1 (Top soil 4 kg+ coir dust 4 kg+ organic manure 4 kg) exhibited the highest seedling height, number of fully opened leaves, leaf area, dry shoot weight and dry root weight. Same as the T1 potting mixture, the T3 potting mixture also showed a considerable increase in plant height, number of fully opened leaves, leaf area, dry shoot weight, dry root weight of coconut seedlings. T3 exhibited the highest soil moisture content and water retention capacity. Therefore, the application of moisture absorbent hydro polymer can be used to get maximum growth and soil moisture characteristics of coconut seedlings.