摘要
为确定以蒸发法为基础设计的土壤水分特征曲线和非饱和渗透系数联合测定仪的可靠性和适用范围,选取粉黏壤土、壤土和壤砂土3种土样进行试验研究。在自然蒸发作用下,利用联合测定仪获得蒸发通量、含水量和土柱表面下方5,10 cm处的基质吸力,以线性假设理论为基础处理实测数据,利用HYDRUS-1D软件进行模拟和反演,输入实测基质吸力和通量数据确定土壤水力参数,利用RETC软件对已处理数据进行VG-Mualem模型拟合。结果表明,含水率符合线性假设理论,基质吸力线性变化不是很理想,但除砂土之外的土样可以通过降低蒸发速率和缩短2次测量时间间隔来解决这个问题;试验数据的拟合效果好,与模拟结果的误差较小,试验前期所测非饱和渗透系数与模拟值误差较大,主要跟含水率接近饱和时水力梯度的精度不能得到保证有关,可以忽略这些数据来改进。使用蒸发法和联合测定仪测定土壤水分特征曲线和非饱和渗透系数具有比较好的可靠性。
[Objective]To determine the reliability and applicability of the soil water characteristic curve and unsaturated permeability coefficient combined measuring instrument designed on the evaporation method,three soil samples were selected:silty clay loam,loam and loamy sand.[Methods]Under natural evaporation,the evaporation flux,water content,and matric suction at 5 and 10 cm below the surface of the soil column were obtained by using the combined measuring instrument.The measured data were processed based on the linear hypothesis.HYDRUS-1D was used for simulation and inversion,and measured matric suction and flux data were input to determine soil hydraulic parameters.VG-Mualem model was fitted to the processed data by using RETC program.[Results]The results show that the moisture content accords with the theory of the linear hypothesis,and the linear variation in matric suction is not ideal.However,soil samples other than sandy soil can solve this problem by reducing the evaporation rate and shortening the interval between two measurements.The fitting effect of the test data is good,and the error is small with the simulation result.The unsaturated permeability coefficient measured in the early stage of the test has a large error with the simulated value,which is mainly due to the inability to ensure the accuracy of the hydraulic gradient when the water content is close to saturation.These data can be ignored for improvement.[Conclusion]It is reliable to use the evaporation method and combined measuring instrument to measure the soil water characteristic curve and unsaturated permeability coefficient.
作者
向峥宇
潘欢迎
邓斌
刘延锋
Xiang Zhengyu;Pan Huanying;Deng Bin;Liu Yanfeng(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China)
出处
《地质科技通报》
CAS
CSCD
北大核心
2023年第4期210-217,共8页
Bulletin of Geological Science and Technology
基金
第三次新疆综合科学考察项目(2022xjkk0304)
国家重点研发项目(2017YFC0406105)
中国地质调查局项目(DD20179605)。
关键词
土壤水分特征曲线
非饱和渗透系数
蒸发法
线性假设理论
联合测定仪
soil water characteristic curve
unsaturated permeability coefficient
evaporation method
theory of linear hypothesis
combined measuring instrument
