The effects of fitting parameters in best fit equations in determination of soil-water characteristic curve and estimation of hydraulic conductivity function

Wang, Shijun; Fan, Weixuan; Zhu, Yiyao; Ju, Zhang

doi:10.1016/j.rhisph.2020.100291

Cited by 5 publications

(3 citation statements)

References 16 publications

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“…Hence, modelling SWCC is challenging, elevating the soil water movement case and is very promising for the future [30,31]. Most recent research indicates the importance of determining SWCC from data in the field and in the laboratory [32][33][34][35]. The shape and format of SWCC depends on soil's physical and hydraulic parameters and has an impact on water behavior and motion [36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Hydraulic Parameters from the Soil Water Characteristic Curve

2023

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Soil water characteristic curve (SWCC) is one of the most essential hydraulic properties that play fundamental role in various environmental issues and water management. SWCC gives important information for water movement, soil behavior, infiltration, and drainage mechanism, affecting the water circle and the aquifer recharge. Since most of the world’s freshwater withdrawals go for irrigation uses, decoding SWCC is beneficial, as it affects water saving through irrigation planning. Estimation of crucial parameters, such as field capacity (FC) and permanent wilting point (PWP) is the key solution for water saving. Modelling of the SWCC and hydraulic parameters estimation are of great importance, since the laboratory experimental procedures and the experiments in the field are often time-consuming processes. In the present study, the SWCC along with FC and PWP of two soil types were obtained via specific experimental procedures in the laboratory. In order to simulate the SWCC and estimate FC and PWP, the experimental data were approximated with van Genuchten’s model. Results showed that using SWCC to estimate FC gives excellent results, while the method rationally overestimates the PWP. Hence, the presented method leads to estimation of crucial hydraulic parameters that can be used in irrigation planning and water saving practices.

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Section: Introductionmentioning

confidence: 99%

Estimation of Hydraulic Parameters from the Soil Water Characteristic Curve

2023

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“…Early researchers believed that the SWCC was a unimodal "s" shaped curve, and several SWCC prediction models were proposed following this shape, such as the widely used Brooks and Corey model [13], Van Genuchten model [14] and Fredlund and Xing model [15]. The parameters of these models were commonly obtained by the optimization method, with the error minimized by iterating the parameters [2,16,17]. To quantitively reflect the influence factors of SWCC, the latest studies tend to estimate the unimodal SWCC for the soil with different initial void ratios using a single fitting function [18].…”

Section: Introductionmentioning

confidence: 99%

Determining the Bimodal Soil–Water Characteristic Curve of Fine-Grained Subgrade Soil Derived from the Compaction Condition by Incorporating Pore Size Distribution

Chen,

Ma,

Zhou

et al. 2023

Processes

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The soil–water characteristic curve (SWCC) is a key constitutive relationship for unsaturated soil which can be unimodal or bimodal. For the fine-grained compacted subgrade soil with a bimodal pattern, the determination of SWCC is complicated and needs a wide-range suction measurement. In this paper, the bimodal SWCC of a subgrade soil derived from the compaction condition was measured and determined by incorporating pore size distribution. For this purpose, a series of laboratory tests were conducted, including the pressure plate method, filter paper method, and vapor equilibrium method, which were used to measure SWCC at the low, medium, and high suction range, respectively. The pore size distribution (PSD) data were obtained by mercury intrusion porosimetry (MIP) tests and used to predict SWCC. Based on the analysis of hydraulic paths and SWCC-PSD correlations, the SWCC of the subgrade soil should be determined to follow the actual hydraulic path. SWCC within a low suction range can be filled by PSD-based data to improve the fitting accuracy. Then, a graphical method is applied to predict the bimodal SWCC by combining the filter paper method, vapor equilibrium method, and PSD-based data. The prediction curves fit well with the test data for all selected compaction conditions. Furthermore, the prediction method can still provide good prediction performance in the absence of high suction section data, which is beneficial for the application of bimodal SWCC.

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“…e accurate estimation of soil hydraulic parameters is crucial in simulating water movement [1][2][3][4], as well as in providing input for related agro-hydrological models (i.e., the Green-Ampt model [5][6][7]).…”

Section: Introductionmentioning

confidence: 99%

Inverse Modelling to Estimate Soil Hydraulic Properties at the Field Scale

Salahou

Chen

Zhang

et al. 2022

Mathematical Problems in Engineering

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Field-scale estimation of soil hydraulic parameters is important for simulating water movement, particularly in the vadose zone. The accuracy of soil hydraulic parameters significantly affects the output of models using these parameters as input variables. A new approach for an inverse method, often referred to as inverse modelling, was presented to calibrate soil hydraulic parameters. The new method is based on the use of uniform design theory to generate uncertainty estimates of the soil hydraulic parameters. The uncalibrated and calibrated soil hydraulic parameters were evaluated by comparing the predicted and measured soil water contents using the HYDRUS-1D model. The results show that the calibrated soil hydraulic parameters that were inversely estimated by uniform design theory were accurate and reasonable. In addition, the results provided recommendations for improving the estimation of soil hydraulic parameters when there are no available observation data for calibrating and optimizing soil hydraulic parameters.

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The effects of fitting parameters in best fit equations in determination of soil-water characteristic curve and estimation of hydraulic conductivity function

Cited by 5 publications

References 16 publications

Estimation of Hydraulic Parameters from the Soil Water Characteristic Curve

Estimation of Hydraulic Parameters from the Soil Water Characteristic Curve

Determining the Bimodal Soil–Water Characteristic Curve of Fine-Grained Subgrade Soil Derived from the Compaction Condition by Incorporating Pore Size Distribution

Inverse Modelling to Estimate Soil Hydraulic Properties at the Field Scale

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