基于黏粒量的土壤水分特征曲线预测模型

目的]建立基于黏粒量的土壤水分特征曲线预测模型.方法]设计12种不同黏粒量的质量混合比处理,获得一系列合成土样,通过测定合成土样的土壤水分特征曲线,研究了在体积质量一致的条件下,黏粒量对土壤水分特征曲线参数和孔隙分布的影响.结果]在体积质量为1.55 g/cm3条件下,黏粒量增加1.9倍,土壤中传导孔隙(0.03...

Using Clay Content to Estimate Soil Water Characteristic Curve

【Objective】Water retention curve is a parameter describing the ability of a soil to hold water;it is modulated by soil structure and texture.The aim of this paper is to evaluate the feasibility of using clay content to estimate water retention curve of a sandy soil.【Method】The sandy soil used in the experiment was sieved to two groups first,and 12 soils with different clay contents were made by thoroughly mixing soils taken from the two groups at different mass fractions.The water retention curve of each sample was measured in laboratory,from which we calculated the pore size distribution and analyzed the impact of the clay content.【Result】When bulk density was 1.55g/cm³,increasing clay content by 1.9 times led to a 28.6%decrease in volume of pores with diameters in the range of 0.03~1 mm,and six times increase in volume of pores with diameter in the range of 200 nm~0.03 mm.Fitting the curves to the van Genuchten formula showed that the parametersθsandαin the formula werepositively proportional to the clay content,while the parameterθrwas negatively proportional to the clay content;the parameter n in the formula decreased exponentially with the clay content.【Conclusion】There were close correlations between all parameters in the van Genuchten formula and the clay content in the sandy soil we studied.These correlations,along with the van Genuchten formula,can be used to estimate the water retention curve of the sandy soil after its clay content changes due to cultivation and/or erosion.For all soils with different clay contents we studied,the absolute errors between the estimated and the observed water contents were less than 15%.These results have implications for numerical simulation of water flow and solute transport in these soils.