Soil cracking propagation due to dryness and its relation to suction

Investigation of Crack Intensity Factor is essential as it affects the mechanical and hydraulic behaviour of soils. Soil water coming from the wet seasons or from the water table, is removed by evaporation during the driest season. The loss of water provokes a significant increase in suction. When it exceeds the tensile strength of the soil, cracks occur that can modify the mechanical and mainly hydraulic properties of the soil, creating preferred paths for water infiltration. Little research is conducted on quantifying cracking in soil relating it to its hydraulic properties. This research aims to investigate the cracking of soils with focus on analysing its relation to water content and soil suction. Soils from a specific region in Brazil with clay predominance are collected and characterized. Unsaturated soil specimens are prepared and subjected to environmental real conditions in order to progressively check the consequences caused by the environment in soils with different clay content during four weeks. The Crack Intensity Factor is measured along the time through image processing. The water content is monitored through volume water content sensors. The measured results are evaluated to correlate crack intensity factor as function of weather variables and soil water content.

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Effect of Biochar Application on Physicochemical and Hydraulic Properties of Loess

Advances in Civil Engineering ◽

10.1155/2020/4592092 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Xiujuan Yang ◽

Henghui Fan ◽

Yuhang Du ◽

Lu Zhang

Keyword(s):

Water Content ◽

Soil Water ◽

Permeability Coefficient ◽

Hydraulic Properties ◽

Water Retention ◽

Water Repellency ◽

Water Infiltration ◽

Water Retention Capacity ◽

Dry Density ◽

Saturated Water

Biochar is important for optimizing soil physical structure and improving soil water retention. The saturated water capacity test, water repellency test, and permeability coefficient test were used to study the effects of biochar additive amount (0, 2, 5, 10, 15, and 20 g/kg) and particle size (>2 mm, 2 mm–0.075 mm, and <0.075 mm) on the basic physicochemical and hydraulic properties of loess. The results showed that with the increase of biochar additive content, the relative particle density decreased linearly (R2 = 0.984); the plastic limit, liquid limit, and plasticity index increased (R2 = 0.947, 0.991, and 0.984, respectively); the maximum dry density decreased (R2 = 0.900); and the optimal water content and saturated water content increased gradually. At the same time, the soil’s pH increased (R2 = 0.957), the soil water repellency decreased, and the water infiltration became easier, but the soil’s permeability coefficient (saturated water conductivity) decreased. When the the biochar particles size is smaller, the soil’s water repellency and permeability coefficient reduced. Studies had shown that the application of biochar makes the loess infiltrate easily, seepage slowly, and contain more water, which improve the water infiltration characteristics and water retention capacity of loess.

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Effects of textural layering on water regimes in sandy soils in a desert-oasis ecotone, Northwestern China

10.5194/egusphere-egu21-9324 ◽

2021 ◽

Author(s):

Chengpeng Sun ◽

Wenzhi Zhao ◽

Hu Liu ◽

Yongyong Zhang ◽

Hong Zhou

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Infiltration ◽

Northwestern China ◽

Soil Profiles ◽

Burial Depth ◽

Layered Soils ◽

Water Regimes ◽

Desert Oasis

Textural layering of soil plays an important role in distributing and regulating resources for plants in many semiarid and arid landscapes. However, the spatial patterns of textural layering and the potential effects on soil hydrology and water regimes are poorly understood, especially in arid sandy soil environments like the desert-oasis ecotones in northwestern China. This work aims to determine the distribution of textural layered soils, analyze the effects of different soil-textural configurations on water regimes, and evaluate which factors affect soil water infiltration and retention characteristics in such a desert-oasis ecotone. We measured soil water content and mineral composition in 87 soil profiles distributed along 3 transects in the study area. Constant-head infiltration experiments were conducted at 9 of the soil profiles with different texture configurations. The results showed that textural layered soils were patchily but extensively distributed throughout the study area (with a combined surface area percentage of about 84%). Soil water content in the profiles ranged from 0.002 to 0.27 g/cm3 during the investigation period, and significantly and positively correlated with the thickness of a medium-textured (silt or silt loam) layer (P < 0.001). The occurrence of a medium-textured layer increased field capacity (FC) and wilting point (WP), and decreased available water-holding capacity in soil profiles. Burial depth of the medium-textured layer had no clear effects on water retention properties, but the layer thickness tended to. In textural layered soils, smaller water infiltration rate and cumulative infiltration, and shallower depths of wetting fronts were detected, compared with homogeneous sand profiles. The thickness and burial depth of medium-textured layers had obvious effects on infiltration, but the magnitude of the effects depended on soil texture configuration. The revealed patterns of soil textural layering and the potential effects on water regimes may provide new insight into the sustainable management of rainfed vegetation in the desert-oasis ecotones of arid northwestern China and other regions with similar environments around the world.

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Using Multivariate Geostatistics to Assess Patterns of Spatial Dependence of Apparent Soil Electrical Conductivity and Selected Soil Properties

The Scientific World JOURNAL ◽

10.1155/2014/712403 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 5

Author(s):

Glécio Machado Siqueira ◽

Jorge Dafonte Dafonte ◽

Montserrat Valcárcel Armesto ◽

Ênio Farias França e Silva

Keyword(s):

Electrical Conductivity ◽

Soil Properties ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Clay Content ◽

Data Sets ◽

Soil Electrical Conductivity ◽

Multivariate Geostatistics ◽

Northwestern Spain

The apparent soil electrical conductivity (ECa) was continuously recorded in three successive dates using electromagnetic induction in horizontal (ECa-H) and vertical (ECa-V) dipole modes at a 6 ha plot located in Northwestern Spain. One of the ECadata sets was used to devise an optimized sampling scheme consisting of 40 points. Soil was sampled at the 0.0–0.3 m depth, in these 40 points, and analyzed for sand, silt, and clay content; gravimetric water content; and electrical conductivity of saturated soil paste. Coefficients of correlation between ECaand gravimetric soil water content (0.685 for ECa-V and 0.649 for ECa-H) were higher than those between ECaand clay content (ranging from 0.197 to 0.495, when different ECarecording dates were taken into account). Ordinary and universal kriging have been used to assess the patterns of spatial variability of the ECadata sets recorded at successive dates and the analyzed soil properties. Ordinary and universal cokriging methods have improved the estimation of gravimetric soil water content using the data of ECaas secondary variable with respect to the use of ordinary kriging.

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Inverse estimation of soil hydraulic properties and water repellency following artificially induced drought stress

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2018-0002 ◽

2018 ◽

Vol 66 (2) ◽

pp. 170-180 ◽

Cited By ~ 7

Author(s):

Vilim Filipović ◽

Thomas Weninger ◽

Lana Filipović ◽

Andreas Schwen ◽

Keith L. Bristow ◽

...

Keyword(s):

Soil Water ◽

Inverse Modeling ◽

Hydraulic Properties ◽

Global Climate ◽

Water Repellency ◽

Irrigation Event ◽

Water Infiltration ◽

Soil Hydraulic Properties ◽

Soil Water Repellency ◽

Soil Hydraulic

AbstractGlobal climate change is projected to continue and result in prolonged and more intense droughts, which can increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, withR2and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (Ks) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.

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Root effects on soil water and hydraulic properties

Biologia ◽

10.2478/s11756-007-0110-8 ◽

2007 ◽

Vol 62 (5) ◽

Cited By ~ 8

Author(s):

Horst Gerke ◽

Rolf Kuchenbuch

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Water Content ◽

Bulk Density ◽

Soil Water ◽

Soil Water Content ◽

Hydraulic Properties ◽

Soil Hydraulic Properties ◽

Soil Hydraulic ◽

Root Effects

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

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Effects of Soil Hydraulic Properties on the Spatial Variability of Soil Water Content

CSA News ◽

10.2134/csa2015-60-3-3 ◽

2015 ◽

Vol 60 (3) ◽

pp. 11-11

Keyword(s):

Spatial Variability ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Hydraulic Properties ◽

Soil Hydraulic Properties ◽

Soil Hydraulic

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Spatial distribution of top soil water content in an experimental catchment of Southeast Brazil

Scientia Agricola ◽

10.1590/s0103-90162011000300003 ◽

2011 ◽

Vol 68 (3) ◽

pp. 285-294 ◽

Cited By ~ 6

Author(s):

Carlos Rogério de Mello ◽

Léo Fernandes Ávila ◽

Lloyd Darrell Norton ◽

Antônio Marciano da Silva ◽

José Márcio de Mello ◽

...

Keyword(s):

Spatial Distribution ◽

Standard Deviation ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Time Domain Reflectometry ◽

Water Infiltration ◽

Local Factor ◽

Top Soil ◽

Over Time

Soil water content is essential to understand the hydrological cycle. It controls the surface runoff generation, water infiltration, soil evaporation and plant transpiration. This work aims to analyze the spatial distribution of top soil water content and to characterize the spatial mean and standard deviation of top soil water content over time in an experimental catchment located in the Mantiqueira Range region, state of Minas Gerais, Brazil. Measurements of top soil water content were carried out every 15 days, between May/2007 and May/2008. Using time-domain reflectometry (TDR) equipment, 69 points were sampled in the top 0.2 m of the soil profile. Geostatistical procedures were applied in all steps of the study. First, the spatial continuity was evaluated, and the experimental semi-variogram was modeled. For the development of top soil water content maps over time a co-kriging procedure was used having the slope as a secondary variable. Rainfall regime controlled the top soil water content during the wet season. Land use was also another fundamental local factor. The spatial standard deviation had low values under dry conditions, and high values under wet conditions. Thus, more variability occurs under wet conditions.

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Soil water contents and displacements monitoring, integrated into a Hydrological-Geotechnical Model for the evaluation of large-scale susceptibility to landslides triggered by rainfalls

10.5194/egusphere-egu2020-5014 ◽

2020 ◽

Author(s):

Roberto Passalacqua ◽

Rossella Bovolenta ◽

Bianca Federici ◽

Alessandro Iacopino

Keyword(s):

Soil Moisture ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Ground Level ◽

Water Infiltration ◽

Landslide Monitoring ◽

Simple Relationship ◽

Capacitive Sensors ◽

Different Depths

Soil water content is often a landslide&#8217;s trigger factor, in particular the shallow ones. Although there is no simple relationship between the water content into the soil and the hydraulic conditions of the slopes at the depths at which the landslides develop, the knowledge of the actual soil moisture is fundamental for the study of landslides, thus, it should be monitored. The LAMP (LAndslide Monitoring and Predicting) system is employed in the INTERREG-ALCOTRA project called AD-VITAM. LAMP (Bovolenta et al., 2016) was yet formulated for the analysis and forecasting of landslides triggered by rain. It adopts a physically based Integrated Hydrological Geotechnical (IHG) model (Passalacqua et al., 2016) and is implemented in GIS. In this Project, the IHG model is fed by data measured using a Wireless Sensor Network (WSN), this formed by low-cost and self-sufficient sensors. The WSN may gather rainfall, temperature, surface&#8217;s displacement data (these by mass-market GNSS receivers in RTK) and, in this case, soil water content (by capacitive sensors). The WaterScout SM100 capacitive sensors were lab-analyzed then, recognized as satisfactory, installed on-site together with their related equipment. These sensors connect to a &#8220;Sensor Pup&#8221;, which has four available channels; therefore, four sensors are installed at each node, at different depths from ground-level, in order to achieve a vertical soil-moisture profile and the rate of infiltration. The selection of the most suitable spots for the water content soil-sensors&#8217; installations depends on the presence of shallow soil layers and of the radio signal emission-reception&#8217;s too. The sensors may be set up both in vertical or horizontal direction. In general, the vertical installation is preferable. This implies the creation of small adjacent vertical holes, each one reaching a different depth, where the sensors are singularly pushed. Alternatively, the horizontal one may be adopted, by the opening of a small trench where the sensors are manually inserted at different depths, along a quasi-vertical vertical line. The full contact between the soil and the sensors is always verified, immediately after the installation, using a directly connected FieldScout reader to any single sensor. Furthermore, it is necessary to protect the emerging cables and to avoid preferential ways for water infiltration along the wiring lines. The monitoring networks, installed at the two Italian sites of Mendatica and Ceriana, are currently providing informations in real-time. The data acquired at five nodes, distributed at each of these two sites (40 sensors in total), are currently relayed on a specific web-portal by a GSM connected Retriever-Modem, marking the evolutions of soil moisture profiles at depths between 10 and 85 cm from ground level: these continuous data allow the analysis of the infiltration and evapotranspiration phenomena. Moreover, a correlation between the soil moisture contents and the local displacements is made possible. Finally, a specific calibration of the SM100 sensors&#8217; in relation to the on-site soil types is in progress.

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