Abstract

Inverse modeling is a relatively complex procedure that allows quick estimation of soil hydraulic properties, yielding parameters for both soil water retention and unsaturated hydraulic conductivity function from a single experiment. The purpose of this research was to evaluate saline water effect on unsaturated hydraulic properties of clay loamy nonsaline-sodic soil layers and estimate these properties inversely from infiltration data using a double-ring infiltrometer.Three levels of water salinity (EC) 1.1, 2.2 and 5.8 dS/m were used for each treatment (T1, T2, and T3, respectively). Soil samples at three depths (0–20, 20–40 and 40–60 cm) were taken to measure Mualem–van Genuchten (MVG) hydraulic parameters (θ_r, residual water content, θ_s, saturated water content, α and n, shape parameters, and K_s, lab saturated hydraulic conductivity). Soil hydraulic parameters were estimated with an inverse solution using HYDRUS-1D model and infiltration data. Besides, the most sensitive MVG parameters to infiltration data (n, θ_s, and K_s) were inversely estimated due to difficulty in estimating several parameters simultaneously. Results showed that salinity had no significant effect on soil water infiltration and soil hydraulic conductivity changes in the specified salinity range according to the variance analyses (ANOVA).The Nash–Sutcliffe coefficient of efficiency (C_e) between simulated (HYDRUS) and measured values of cumulative infiltration data was about 0.998, indicating an excellent match. Soil water retention, as well as unsaturated soil hydraulic conductivity, were optimized with reasonable accuracy when the soil profile was assumed to be homogenous. In addition, simulated soil-water contents were quite similar to the measured values in which the values of Nash–Sutcliffe efficiency (C_e) for T1, T2, and T3 were 0.83, 0.85, and 0.85, respectively. In conclusion, the soil hydraulic parameters can be inversely estimated using the measured infiltration data through the double ring method if the soil is homogeneous.

中文翻译：

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基于盐水双环渗透的非饱和土壤水力特性

摘要

逆建模是一个相对复杂的过程，可以通过一次实验快速估算土壤的水力特性，获得土壤保水率和不饱和水力传导率函数的参数。这项研究的目的是评估盐水对黏土壤土非盐碱土层的不饱和水力特性的影响，并使用双环渗透仪从渗透数据反演估计这些特性。三种水盐度（EC）1.1、2.2和每种处理使用5.8 dS / m（分别为T1，T2和T3）。在三个深度（0-20，20-40和40-60厘米）的土壤样本进行测量穆阿利姆-求算Van Genuchten（MVG）液压参数（θ _{- [R} ，残留水含量，θ_小号，饱和水含量，α和n，形状参数和K _s（实验室饱和导水率）。使用HYDRUS-1D模型和入渗数据，通过反解估算土壤水力参数。此外，最敏感的MVG参数浸润数据（Ñ，θ_小号和ķ_小号）呈负由于在同时估计几个参数估计困难。结果表明，根据方差分析（ANOVA），在指定的盐度范围内，盐度对土壤水分入渗和土壤水力传导率的变化均无显着影响。纳什-萨特克利夫效率系数（C _e模拟（HYDRUS）与测得的累积入渗数据之间的差值约为0.998，这表明二者之间具有极好的匹配性。当假定土壤剖面是均质的时，以合理的精度优化了土壤保水率以及不饱和土壤的水力传导率。此外，模拟的土壤水含量与测量值非常相似，其中T1，T2和T3的纳什-萨特克利夫效率（C _e）的值分别为0.83、0.85和0.85。总之，如果土壤是均质的，则可以通过双环法使用测得的入渗数据反算土壤水力参数。