Cross-sectional view of (a) full domain of interest; (b) boundary conditions of modeled half domain; (c) details of modeled perimeter crack in 3-D simulation; (d) the 2-D scenario used for obtaining the approximation for subslab perimeter crack concentration (Yao et al., 2012).
Hydrus 2d 3d Crack In Paperl
Paper # 2200367 Experimental study on dynamic characteristics of corn combine harvester frame with crack damage (Content Removed)
Citation: Paper number 2200367, 2022 ASABE Annual International Meeting. (doi: 10.13031/aim.202200367) @2022
Authors: (Content Removed)
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Cracks are common in clay or expansive clay soils, which are recognized as one of the reasons to form preferential flow, involving water bypassing a large portion of the soil matrix and widely considered to be a common phenomenon in hydrology. Within those cracks, the infiltration water will reach the groundwater directly and quickly, and therefore reduce the irrigation efficiency. What is more, a variety of materials in soils, including heavy metals, radionuclides, pesticides, and contaminants, cause the environmental issues through preferential flow paths.
When rainwater enters a cracked soil on a sloping surface, it flows in the network of cracks and seeps into the soil matrix and finally can influence hillside hydrology [1, 2]. As water moves in the network of cracks, there is an increase in the lateral flow rate through the soil as compared to flow through intact soils [3, 4]. Consequently, the occurrences of cracks in the soil influence the water movement in the soil. The dynamic parameters of overland flow are also influenced by the drying shrinkage cracks in the soil, leading to the reduction of the unit discharge and the number of Reynolds, and the overland flow decreased accordingly. In addition, the cracks can have a dramatic effect on the processes of surface water movement and flood dynamics by altering the partitioning of rainfall between infiltration and runoff, which is an important issue in modeling and forecasting flood events. Therefore, it is important to investigate the impact of soil crack networks on overland flow and water infiltration into soils, which will improve the understanding of physical basis of nonuniform water movement in soil.
Water movement and solute transport in cracked soil have been widely investigated in the fields of geotechnical engineering, agriculture, and environmental sciences [1, 2]. The permeability of cracked soil is highly anisotropic due to the cracks. The permeability in the predominant direction of cracking is larger than that in other directions. Krisnanto et al. [44] used the model to predict the lateral flow rate through a network of cracks in the soils. Zhang et al. [45] simulated the water infiltration rate by considering the crack property. It is generally agreed that it will be difficult to quantitatively describe the anisotropic properties of cracked soil without an appropriate 3D crack network model. In the crack network model, the permeability tensor is often used to represent the anisotropic properties of a cracked medium [46, 47]. The permeability of cracked soil is often analyzed by means of continuum mechanics methods based on the permeability of the soil matrix and crack network [48], and thus the permeability tensor must be determined. Khoei et al. [49] have developed a numerical method to simulate the two-phase fluid flow through fractured porous media based on the linear momentum balance equation and the flow continuity equation. Li et al. [50], Krisnanto et al. [3], and Pierlot et al. [42] developed a method to determine whether a network of cracks can be considered as a continuum with anisotropic characteristics for the saturated coefficient of permeability.
In this study, the dye-tracing experiments were conducted that simulated a series of natural rainfall amounts. In conjunction with laboratory experiments, numerical modelling was built to simulate coupled water movement in soil crack networks, surface water, and groundwater flow under the experimental conditions.
The SMC (surface-matrix-crack) model can simulate water flow within discrete fracture as well as water flow in the soil matrix based on the dual-permeability concept using the equivalent freshwater formulation.
The variance of infiltration depth was further analyzed to compare the infiltration uniformity of the sections. The variance is written as follows:where is the infiltration depth of each vertical pixel line of the experiment and is the depth of the average infiltration of the experiment. The variance of experiments S1, S2, S3, S4, and S5, respectively, is 25.2, 74.9, 108.4, 5.6, and 8.6, which indicates that the uniformity of soil water infiltration is affected by cracks, and the values of variance for those experiments that have cracks are higher than those in the noncrack experiments. In addition, high precipitation intensity will decrease the uniformity of soil water infiltration.
Figure 11 shows that the SMC model can estimate the discharge at a high accuracy compared against the observed values, with relative error of 9.71% and 5.0% for experiments S2 and S3. This may result from the fact that our model considers the existence of the fracture networks. It also indicates that the model can simulate the overall flow of surface runoff, and the existence of the cracks may delay the production of surface runoff.
In this paper, the artificial soil fracture network and the hillslope system of a relatively large slope were utilized for our analysis. However, in field condition, the distribution of soil cracks is not clear and the soil surface is rough. Therefore, the extent of the fracture network, the spatial structure, and the soil surface roughness of the fracture will be considered in our further work.
Highlights. (i) Dye-tracing experiments were conducted to investigate the surface runoff and the soil water movement in the presence of the fracture network. (ii) The effect of the fracture network on the soil water and overland flow was analyzed under different precipitation intensities and durations. (iii) Numerical model was built to simulate the coupled surface water flow and subsurface flow in soil crack networks and in soil matrix.
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