scholarly journals Interaction of soil water and groundwater during the freezing–thawing cycle: field observations and numerical modeling

2021 ◽  
Vol 25 (8) ◽  
pp. 4243-4257
Author(s):  
Hong-Yu Xie ◽  
Xiao-Wei Jiang ◽  
Shu-Cong Tan ◽  
Li Wan ◽  
Xu-Sheng Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Water Content ◽  
Soil Water ◽  
Water Table ◽  
Groundwater Level ◽  
Water Table Depth ◽  
Field Observations ◽  
Initial Water ◽  
Groundwater Inflow ◽  
The Mean

Abstract. Freezing-induced groundwater-level decline is widely observed in regions with a shallow water table, but many existing studies on freezing-induced groundwater migration do not account for freezing-induced water-level fluctuations. Here, by combining detailed field observations of liquid soil water content and groundwater-level fluctuations at a site in the Ordos Plateau, China, and numerical modeling, we showed that the interaction of soil water and groundwater dynamics was controlled by wintertime atmospheric conditions and topographically driven lateral groundwater inflow. With an initial water table depth of 120 cm and a lateral groundwater inflow rate of 1.03 mm d−1, the observed freezing and thawing-induced fluctuations of soil water content and groundwater level are well reproduced. By calculating the budget of groundwater, the mean upward flux of freezing-induced groundwater loss is 1.46 mm d−1 for 93 d, while the mean flux of thawing-induced groundwater recharge is as high as 3.94 mm d−1 for 32 d. These results could be useful for local water resources management when encountering seasonally frozen soils and for future studies on two- or three-dimensional transient groundwater flow in semi-arid and seasonally frozen regions. By comparing models under a series of conditions, we found the magnitude of freezing-induced groundwater loss decreases with initial water table depth and increases with the rate of groundwater inflow. We also found a fixed-head lower boundary condition would overestimate freezing-induced groundwater migration when the water table depth is shallow. Therefore, an accurate characterization of freezing-induced water table decline is critical to quantifying the contribution of groundwater to hydrological and ecological processes in cold regions.

scholarly journals Interaction of soil water and groundwater during the freezing-thawing cycle: field observations and numerical modeling

2021 ◽  
Author(s):  
Hong-Yu Xie ◽  
Xiao-Wei Jiang ◽  
Shu-Cong Tan ◽  
Li Wan ◽  
Xu-Sheng Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Water Level ◽  
Soil Water ◽  
Groundwater Level ◽  
Field Observations ◽  
Water Migration ◽  
Freezing And Thawing ◽  
Groundwater Inflow ◽  
The Mean ◽  
Water Level Decline

Abstract. Freezing-induced water migration and groundwater level decline are widely observed in regions with shallow water table, but many existing studies trying to quantify freezing-induced groundwater migration do not account for water level fluctuations induced by freezing and thawing. Here, detailed field observations of liquid soil water content and groundwater level fluctuations at a site in the Ordos Plateau, China are combined with numerical modeling to show groundwater and soil water dynamics controlled by wintertime atmospheric conditions and topographically-driven lateral groundwater inflow. By comparing simulation results with and without lateral groundwater inflow, we find lateral groundwater inflow leads to an alleviated freezing-induced water level decline and enhanced freezing-induced water migration. At the field site with a lateral groundwater inflow rate of 1.03 mm/d, compared with the case without lateral groundwater inflow, the water level decline decreases from 40 cm to 15 cm, and the increased total water content in the frozen zone enhances from 0.071 to 0.106. By calculating the budget of groundwater, the mean upward flux of freezing-induced groundwater loss is 1.46 mm/d for 93 days, and the mean flux of thawing-induced groundwater gain is as high as 3.94 mm/d for 32 days. The study enhances our understanding of the mechanisms controlling water redistribution between saturated and unsaturated zones and the water budget in the freezing-thawing cycle. The fluxes of groundwater loss and gain in the freezing and thawing stages obtained in the current study can be useful for future studies on two- or three-dimensional transient groundwater flow in semi-arid regions with seasonally frozen soils.

scholarly journals Study on the Mechanical Criterion of Ice Lens Formation Based on Pore Size Distribution

2020 ◽  
Vol 10 (24) ◽  
pp. 8981
Author(s):  
Yuhang Liu ◽  
Dongqing Li ◽  
Lei Chen ◽  
Feng Ming
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Water Content ◽  
Size Distribution ◽  
Initial Water Content ◽  
Mean Stress ◽  
Initial Water ◽  
Unfrozen Water Content ◽  
The Mean ◽  
Lens Formation

Ice lens is the key factor which determines the frost heave in engineering construction in cold regions. At present, several theories have been proposed to describe the formation of ice lens. However, most of these theories analyzed the ice lens formation from a macroscopic view and ignored the influence of microscopic pore sizes and structures. Meanwhile, these theories lacked the support of measured data. To solve this problem, the microscopic crystallization stress was converted into the macro mean stress through the principle of statistics with the consideration of pore size distribution. The mean stress was treated as the driving force of the formation of ice lens and induced into the criterion of ice lens formation. The influence of pore structure and unfrozen water content on the mean stress was analyzed. The results indicate that the microcosmic crystallization pressure can be converted into the macro mean stress through the principle of statistics. Larger mean stress means the ice lens will be formed easier in the soil. The mean stress is positively correlated with initial water content. At the same temperature, an increase to both the initial water content and the number of pores can result in a larger mean stress. Under the same initial water content, mean stress increases with decreasing temperature. The result provides a theoretical basis for studying ice lens formation from the crystallization theory.

scholarly journals Platelet Water Content is Decreased by Gel-Filtration

1977 ◽  
Author(s):  
J.S. Wiley ◽  
G. Wray ◽  
I.A. Cooper
Keyword(s):  
Water Content ◽  
Gel Filtration ◽  
Normal Subjects ◽  
Intracellular Water ◽  
Total Water ◽  
Initial Water ◽  
Mean Cell Volume ◽  
Cell Pellet ◽  
The Mean ◽  
Water Space

One approach to platelet sizing is to measure the intracellular water space of platelets with 3H-H2O since the % water content of platelets remains constant in states with different platelet sizes. Fresh citrated blood was centrifuged for 10 min at 150 'g' to obtain PRP. Aliquots of PRP were briefly incubated with either 3H-H2O or 14C-sucrose then layered over 0.3 ml dibutylphthalate and spun 4 min at 8000 'g'. The cell pellet was solubilized and counted to enable spaces to be calculated. The extracellular (sucrose) space was subtracted from the total water space of the pellet to give a mean intracellular water space of 0.56 ± 0.12 μ1/108 platelets (n =19). Assuming a water content of 7 5% and a density of 1.04, the mean platelet volume for normal subjects is 7.2 fl. Gel-filtration of platelets (GFP) on Sepharose-2B reduced their mean water space by 0.12 μl/108 platelets. However the amount of shrinkage on gel-filtration depended on the initial water space of the platelets in PRP and there was a linear relation between these two variables (r = 0.82). Shrinkage was 40% for an initial platelet water space of 0.70 μl/108 platelets but there was almost no shrinkage below a water space of 0.40 μl/108 platelets. Recovery of platelets from each column averaged 8 0% and showed no relation to the reduction in the mean cell water space. The lower water space of GFP may indicate a reduction in mean cell volume due to gel-filtration.

Field observations of soil water content and nitrogen distribution on two hillslopes of different shape

2015 ◽  
Vol 525 ◽  
pp. 694-705 ◽  
Author(s):  
Yong Li ◽  
Manli Huang ◽  
Jianlan Hua ◽  
Zhentin Zhang ◽  
Lixiao Ni ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Observations ◽  
Nitrogen Distribution

EFFECT OF SOIL WATER STATUS AND STRENGTH ON TRAFFICABILITY

1979 ◽  
Vol 59 (3) ◽  
pp. 313-324 ◽  
Author(s):  
C. L. PAUL ◽  
J. DE VRIES
Keyword(s):  
Soil Water ◽  
Water Table ◽  
Structural Damage ◽  
Water Status ◽  
Water Table Depth ◽  
Silty Clay ◽  
Clay Loam ◽  
Silty Clay Loam ◽  
Soil Water Tension ◽  
Farm Vehicles

Trafficability tests with typical farm vehicles were carried out on three lowland fields at various degrees of wetness. Structural damage after the first and third passes was assessed in terms of bulk density, aeration porosity, pore-size distribution and rut depth. These indices could not be used per se as criteria for trafficable conditions because of lack of information concerning their relationship to plant growth. Instead, a trafficability criterion oriented toward traction efficiency was established by determining for each soil the relationship between its strength (assessed with a cone penetrometer) and traction efficiency measured by wheelslip. A critical value of strength for trafficability was inferred from this relationship. This was then used to obtain soil water tension limits for trafficability from known relations between tension and strength. Soil strength was found to be linearly dependent upon water table depth in spring when evapotranspiration was small and when the water table depth was less than 80 cm. Consideration of these relationships led to the establishment of critical water table limits for trafficability. These were 53, 45, and 60 cm for Lumbum muck, Hallart silty clay loam (SiCL) (grassland), and Hallart silty clay loam (cultivated), respectively.

scholarly journals Effect of initial gravimetric water content and cyclic wetting-drying on soil-water characteristic curves of disintegrated carbonaceous mudstone

2019 ◽  
Vol 1 (3) ◽  
pp. 230-240
Author(s):  
Ling Zeng ◽  
Fan Li ◽  
Jie Liu ◽  
Qianfeng Gao ◽  
Hanbing Bian
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Characteristic Curve ◽  
Initial Water Content ◽  
Test Results ◽  
Initial Water ◽  
Soil Water Characteristic Curves ◽  
Water Holding ◽  
Gravimetric Water Content ◽  
Plate Apparatus

Abstract The soil-water characteristic curve (SWCC) is often used to estimate unsaturated soil properties (e.g. strength, permeability, volume change, solute and thermal diffusivity). The SWCC of soil samples is significantly affected by cyclic wetting-drying. To examine how water content and cyclic wetting-drying affect the SWCC of disintegrated carbonaceous mudstone (DCM), SWCC tests were implemented using a pressure-plate apparatus. In addition, SWCC models for DCM considering the initial gravimetric water content and cyclic wetting-drying were developed. The test results showed that the volumetric water content (θ) of the DCM first decreased rapidly and then became stable as matric suction (s) increased. The initial water content affected the SWCC by altering the pore structure of the DCM. For a given number of wetting-drying cycles, the higher the initial water content, the higher the stabilized θ. At a given s value, θ decreased as the number of wetting-drying cycles increased, which suggests that cyclic wetting-drying reduces the water-holding capacity of DCM. The Gardner model for DCM was constructed considering initial water content and cyclic wetting-drying, and was effective at describing and predicting the SWCC model for DCM.

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