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为探明黄土高原北部冻融过程对土壤饱和导水率的影响,采用冻融循环模拟的方法,分析了不同土地利用和不同土层深度下冻融循环前后土壤饱和导水率(Ks)的变化特征。结果表明:冻融过程对Ks有显著影响,经15次冻融循环后,Ks总体上呈减小趋势,其影响程度因土地利用类型和土层深度不同而异。冻融循环后4种土地利用0~10 cm土层Ks均显著下降,柠条林地下降幅度最大,其次为农地、苜蓿地和撂荒地,这与土壤的松散程度有关。除撂荒地外,冻融循环过程对其它3种土地利用10~20和20~40 cm土层Ks无显著影响。4种土地利用0~10 cm土壤田间持水量和饱和含水量经冻融循环后均有不同程度下降,表明冻融循环后土壤孔隙度降低度降低。研究可为揭示冻融循环对黄土区土壤饱和导水率的影响机理以及为土壤水分匮乏的寒区旱区春季降水及积雪融水的高效利用提供理论依据。
In order to find out the influence of freeze-thaw process on saturated hydraulic conductivity of soil in northern Loess Plateau, the saturated hydraulic conductivity (Ks) of soil before and after freeze-thaw cycles under different land use and depth were analyzed by freeze-thaw cycle simulation Change characteristics. The results showed that the freeze-thaw process had a significant effect on Ks. After 15 cycles of freeze-thaw cycles, Ks generally showed a decreasing trend, and the degree of influence varied according to the type of land use and soil depth. The Ks of 0 ~ 10 cm soil layer of four kinds of land use after freezing and thawing cycle decreased significantly, and the decline rate of Caragana korshinskii was the largest, followed by that of farmland, alfalfa and fallow land, which was related to the degree of soil looseness. In addition to wasteland, the freeze-thaw cycles had no significant effect on Ks at 10-20 and 20-40 cm depths in the other three areas. The field water holding capacity and saturated water content of 0 ~ 10 cm soil of four kinds of land use decreased after freezing and thawing cycles, which showed that the degree of decrease of soil porosity after freezing and thawing cycles decreased. The research may provide a theoretical basis for revealing the influence mechanism of freeze-thaw cycles on saturated hydraulic conductivity of loess soils, as well as providing theoretical basis for spring rainfall and efficient utilization of snowmelt water in the cold and dry arid regions where soil moisture is scarce.