scholarly journals Experimental and Numerical Analysis of Soil Cracking Characteristics under Evaporation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Di Feng ◽  
Jiakun Gong ◽  
Xiaodong Ni ◽  
Jie Ren
Keyword(s):  
Soil Moisture ◽  
Developmental Stages ◽  
Water Movement ◽  
Soil Surface ◽  
Geometrical Parameters ◽  
Dynamic Prediction ◽  
Moisture Movement ◽  
Cracking Characteristics ◽  
Cracked Soil ◽  
Soil Cracks

There are numerous cracks on soil surface in nature. These cracks are mainly formed by the continuous water loss and shrinkage of soil under evaporation. Cracks have an important effect on the properties of soil. The analysis of soil moisture movement and cracking characteristics under evaporation is of great significance to the engineering construction in the cracked soil area. In this work, an experimental study was conducted to investigate the development of soil cracks. Crack geometrical parameters were acquired at various developmental stages. According to this, the crack evolution characteristic was described qualitatively. The law of soil water movement was analyzed through the numerical simulation of evaporation effect on cracked soil. The relationship between soil moisture content and crack width was revealed, and the dynamic prediction of crack development under evaporation was realized. The results show that the development and evaporation process of soil cracks can be divided into three distinct stages, and the longer the stable evaporation time, the greater the development of cracks.

scholarly journals Management of Bio-Waste by the Paper Mulch

2021 ◽  
Vol 1 ◽  
Author(s):  
Zahra Mohebi
Keyword(s):  
Soil Moisture ◽  
Plant Growth ◽  
Leaf Litter ◽  
Ecosystem Health ◽  
Water Movement ◽  
Soil Surface ◽  
Beneficial Effects ◽  
Weed Growth ◽  
Micro Organisms ◽  
Office Waste

Mulch is a type of protective covering placed on or spread over the soil surface that helps to conserve soil moisture, suppress weed growth and enrich the soil. The paper mulch is the most complete mulch and has numerous beneficial effects upon the soil and plants. This mulch which is produced from office waste paper, newspaper and wrapping papers, conserves soil moisture, is effective at suppressing and inhibiting weed growth, enhances agro-ecosystem health by improving the air and water movement through the soil; providing moist conditions thereby promoting micro-organisms and worm populations; promoting plant growth and product, promoting leaf litter build up and helping to improve the pH balance in the soil.

scholarly journals Hydro-depositary and hydro-transmitting properties of soddy-podzolic soils in the course of simulating the water transfer by physically-grounded models

2015 ◽  
pp. 71-82
Author(s):  
E. V. Shein ◽  
E. B. Skvortsova ◽  
S. S. Panina ◽  
A. B. Umarova ◽  
K. A. Romanenko
Keyword(s):  
Field Experiments ◽  
Water Movement ◽  
Soil Surface ◽  
Soddy Podzolic Soil ◽  
Water Layer ◽  
Special Method ◽  
Moisture Movement ◽  
Podzolic Soils ◽  
Constant Head ◽  
Better Than

The results of field experiments conducted on the medium loamy agro soddy-podzolic soil showed that due to the hydraulic head of water at the soil surface the moisture movement occurs predominantly through migration ways that deteriorate the hydro-depositary properties of soils. The moisture movement was studied by a special method performed in two soil monoliths identical in size (42 cm in diameter and 60 cm high). The monolith walls were covered by a film, foamed and buried with the view of avoiding the lateral water loss. Both monoliths were simultaneously saturated with water: one of them was under a constant head of water in 5 cm, the other monolith was watered by fine-dispersed sprinkler without the formation of the water layer at the soil surface. The study was aimed at modeling the water movement under conditions of small headed infiltration and without the head of water as well as comparing the calculated and experimental data with the view of assessing the most adequate experimental provision of the model - the major hydrophysical characteristics obtained by empiric methods in the experiment or those calculated on the basis of hydrological constants and soil properties (pedo-transmitting functions). It seemed reasonable to establish that the experimental provision of the model can be shown in the following order: the use of regional pedo-transmitting functions provides better results as compared to the major hydrophysical characteristics, the latter being obtained by the method of tensiometers and capillarometers is better than the pedo-transmitting characteristics used the particle-size distribution as a predictor in Agrotool program (ROSETTA database) as well as those obtained by Voronin’s “secants”.

Numerical Analysis for Unsaturated Water Movement in Soil of Changing Bulk Density

2011 ◽  
Vol 137 ◽  
pp. 221-226
Author(s):  
Song Bai Cai ◽  
Ming An Shao ◽  
Dian Qing Lu ◽  
Xiao Li Fu ◽  
Da Zhi Li
Keyword(s):  
Soil Moisture ◽  
Bulk Density ◽  
Difference Method ◽  
Water Movement ◽  
Rapid Development ◽  
Soil Column ◽  
Large Set ◽  
Algebraic Equations ◽  
Moisture Movement ◽  
Linear Algebraic Equations

With the rapid development of computers and computing techniques, some increasingly complicated computational problems in engineering and science deserve further review and improvement. This work calculated the solution to the problem of Richards partial differential equation with its corresponding initial and boundary condition for one-dimensional unsaturated water movement in soil with changing bulk density by adopting an explicit backward difference method, an implicit forward difference method and an implicit central difference method. Therefore, a temporal-spatial distribution of water content in the process of filtration, evaporation and redistribution of water moisture within the soil column was obtained. Then the computational results were compared and verified, alternatively, by three methods, with a semi-analytical solution. This indicates the methods presented are of high validity, efficiency and accuracy. These methods were used for the first time for the modelling and prediction of the complicated water movement process in soil of changing bulk density. The computations show that the explicit method features a simpler formulation and more capability for complicated modelling, and the authors strongly recommend this method for application in time-related problems. In addition, this work innovatively developed a combination procedure of an implicit difference method and iterative solution method of a large set of linear algebraic equations. It not only avoids solving a large set of linear algebraic equations but also is able to be applied to complicated modelling of soil moisture profiles. Finally, the numerical methods and the technical skills presented in this work can be generalised for two-dimensional or three-dimensional soil moisture movement and more complicated water movement modeling.

A Conceptual Model of Soil Moisture Movement in Seasonal Frozen Unsaturated Zone

2011 ◽  
Vol 90-93 ◽  
pp. 2612-2618 ◽  
Author(s):  
Si Miao Sun ◽  
Chang Lei Dai ◽  
Hou Chu Liao ◽  
Di Fang Xiao
Keyword(s):  
Soil Moisture ◽  
Conceptual Model ◽  
Unsaturated Zone ◽  
Soil Surface ◽  
Frozen Soil ◽  
Freezing And Thawing ◽  
Moisture Movement ◽  
Freeze Thaw ◽  
Surface Evaporation ◽  
Thawing Process

Conceptual model is considered as one of the crucial and essential methods for scientific research on cold region hydrology. However, graphical conceptual model that integrates with a variety of influencing factors and specializes in describing soil moisture dynamic in seasonal frozen unsaturated zone has never occurred in any related researches, due to which the study on mechanism of frozen soil moisture movement has been delayed in a certain degree. Firstly, three stages of freezing and thawing process are divided in this article to serve for the further study in seasonal frozen unsaturated zone, which respectively are: the Stage of Freezing (Instable Freezing Stage and Stable Freezing Stage), the Stage of Thawing (Instable Thawing Stage and Stable Thawing Stage) and the Stage of Freeze-free. Secondly, based on different stages above, three characteristics and the relationships are analyzed, which include freeze-thaw-action and groundwater table, freeze-thaw-action and groundwater storage, freeze-thaw-action and soil surface evaporation. Thirdly, referred to related theories (Frozen Soil Hydrology and Snow & Ice Hydrology) and the construction of watershed model in warm regions, a whole set of graphical conceptual model and corresponding symbolic model have been built with freezing and thawing process as x-axis (time coordinate) and both soil frozen depth and different parameters as double y-axis. The different parameters include groundwater depth, soil water moisture rate and soil surface evaporation intensity. The graphical and symbolic conceptual models comprehensively describe the entire process and the factors relationships of soil moisture movement in seasonal frozen unsaturated zone. These models are expected to provide scientific basis for practical work in cold areas, such as hydrologic and hydraulic calculation in cold seasons, assessment and utilization of frozen area water resources and agricultural irrigation in cold regions, and also to provide references to the development of mathematical or experimental models in related researching fields.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

scholarly journals Potential Applications of GNSS-R Observations over Agricultural Areas: Results from the GLORI Airborne Campaign

2018 ◽  
Vol 10 (8) ◽  
pp. 1245 ◽  
Author(s):  
Mehrez Zribi ◽  
Erwan Motte ◽  
Nicolas Baghdadi ◽  
Frédéric Baup ◽  
Sylvia Dayau ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Signal To Noise Ratio ◽  
Soil Surface ◽  
Satellite System ◽  
Area Index ◽  
Vegetation Height ◽  
Study Sites ◽  
Global Navigation Satellite ◽  
Vegetation Characteristic ◽  
Agricultural Areas

The aim of this study is to analyze the sensitivity of airborne Global Navigation Satellite System Reflectometry (GNSS-R) on soil surface and vegetation cover characteristics in agricultural areas. Airborne polarimetric GNSS-R data were acquired in the context of the GLORI’2015 campaign over two study sites in Southwest France in June and July of 2015. Ground measurements of soil surface parameters (moisture content) and vegetation characteristics (leaf area index (LAI), and vegetation height) were recorded for different types of crops (corn, sunflower, wheat, soybean, vegetable) simultaneously with the airborne GNSS-R measurements. Three GNSS-R observables (apparent reflectivity, the reflected signal-to-noise-ratio (SNR), and the polarimetric ratio (PR)) were found to be well correlated with soil moisture and a major vegetation characteristic (LAI). A tau-omega model was used to explain the dependence of the GNSS-R reflectivity on both the soil moisture and vegetation parameters.

scholarly journals The environmental forming and productional functions of the haloxylon aphyllum in the Karnabchul desert

2019 ◽  
pp. 34-38
Author(s):  
E. Z. Shamsutdinova
Keyword(s):  
Soil Moisture ◽  
Outer Part ◽  
Soil Surface ◽  
Hydrothermal Conditions ◽  
Noticeable Effect ◽  
Soil Layers ◽  
Haloxylon Aphyllum ◽  
Aged State ◽  
Ephemeral Vegetation ◽  
Black Saxaul

We have conducted investigation of the environmental function of the desert tree of black saxaul (Haloxylon aphyllum) in the Karnabchul desert. As a result, it was found that different age plants of black saxaul had different effects on the degree of illumination. The greatest influence on the intensity of solar radiation was exerted by the saxaul plant of the black middle-aged state, the least the old generative individuals. Saxaul black had a significant impact on the temperature of the air: in the daytime, especially in the period 13-16 h, reducing the temperature under the crown and on the edge of the crown, and at night increasing it in the same areas. It also had a noticeable effect on the temperature of the soil. The temperature of the soil surface under the crown at night is higher, and during the day the warming was slower than in the outer part of the saxaul crown. Under the influence of black saxaul and soil moisture changed. Under the saxaul crown soil moisture is significantly higher compared to the control (open natural pastures). The highest soil moisture was observed in the upper soil layers at the base of the saxaul trunk. As a result, under the environmental action of black saxaul more favorable hydrothermal conditions for the growth and development of natural wormwood-ephemeral vegetation under the protection of strips and adjacent areas of pastures are formed. The result of production activities chemotaxonomic postbestowal bands consists of two following components: production of fodder mass of the Haloxylon and fodder productivity of wormwood-ephemeral vegetation of natural pastures. By increasing the yield of natural pastures under the protection of pasture protection strips and the harvest of the black saxaul fodder productivity of desert pastures increases more than twice.

scholarly journals Spreading of chemical substance after its accidental spillage onto the soil surface under unsaturated conditions and variable porosity

2019 ◽  
pp. 41-44
Author(s):  
Olena Kozhushko ◽  
Petro Martyniuk
Keyword(s):  
Mathematical Model ◽  
Soil Moisture ◽  
Soil Profile ◽  
Moisture Transport ◽  
Soil Surface ◽  
Chemical Substance ◽  
High Concentration ◽  
Solute Transfer ◽  
Variable Porosity ◽  
The One

In this paper we study a mathematical model of soil moisture transport with variable porosity. The problem is set for the case of highly concentrated solute spilled onto soil surface. We investigate the way solute transfer, adsorption of contaminant by soil particles and variable porosity influence infiltration of solute into the soil profile. For that purpose, two models are used: a classical one and the one with consideration of mentioned factors. By comparing the results of both models, we established that high concentration of solute causes moisture transport to transpire more slowly, and the pollutant to remain on the soil surface for longer time. Numerical results indicate that porosity can vary considerably under the conditions of intensive contamination with salts.

scholarly journals The Influence of Moss Colonization and Biochar Application on Evaporation Losses and Surface Crack in Shallow Carbonate–Derived Laterite During Dry–Wet Cycles

2021 ◽  
Author(s):  
Lulu Che ◽  
Dongdong Liu ◽  
Dongli She
Keyword(s):  
Soil Moisture ◽  
Soil Surface ◽  
Soil Evaporation ◽  
Interactive Effects ◽  
Surface Cracks ◽  
Evaporation Model ◽  
Soil Desiccation ◽  
Evaporation Losses ◽  
Soil Moisture Conservation ◽  
Surface Temperature Field

Abstract AimsSoil water deficit in karst mountain lands is becoming an issue of concern owing to porous, fissured, and soluble nature of underlying karst bedrock. It is important to identify feasible methods to facilitate soil water preservation in karst mountainous lands. This study aims to seek the possibility of combined utilization of moss colonization and biochar application to reduce evaporation losses in carbonate-derived laterite.MethodsThe treatments of the experiments at micro-lysimeter included four moss spore amounts (0, 30, 60, and 90 g·m−2) and four biochar application levels (0, 100, 400, and 700 g·m−3). The dynamics of moss coverage, characteristics of soil surface cracks and surface temperature field were identified. An empirical evaporation model considering the interactive effects of moss colonization and biochar application was proposed and assessed.ResultsMoss colonization reduced significantly the ratio of soil desiccation cracks. Relative cumulative evaporation decreased linearly with increasing moss coverage under four biochar application levels. Biochar application reduced critical moss coverage associated with inhibition of evaporation by 33.26%-44.34%. The empirical evaporation model enabled the calculation of soil evaporation losses under moss colonization and biochar application, with the R2 values ranging from 0.94 to 0.99.Conclusions Our result showed that the artificially cultivated moss, which was induced by moss spores and biochar, decreased soil evaporation by reducing soil surface cracks, increasing soil moisture and soil surface temperature.Moss colonization and biochar application has the potential to facilitate soil moisture conservation in karst mountain lands.

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