不同土地利用方式下次降雨对土壤含水量深层变化的影响

[目的]黄土高原地区水资源短缺，探究不同土地利用方式下次降雨对土壤含水量变化的影响对区域水资源优化配置理论探索具有重要意义。[方法]基于甘肃省庆阳市南小河沟径流场自然降雨条件下的实测数据资料及4种土地利用方式(农、林、草、裸)覆盖下的降雨前后观测数据，分析了不同土地利用方式下5种不同次降雨等级的土壤含水量深层变化特征。[结果](1)土壤含水量的动态变化与土地利用方式关系较为密切。在4种土地利用方式中，林地比裸地的蓄水能力好，但裸地的土壤含水量在不同等级降雨影响下的波动最大。随着土层深度的增加，表层土壤含水量对降雨的响应比较明显，中间层和深层具有一定的滞后性。(2)特定降雨条件下，土壤不同深度的水分交换存在明显的水分活跃层分界点。大雨和暴雨条件下，在40 cm土层深度处出现明显的水分活跃层分界点；中雨条件下，除了农地雨后含水量差异较大之外，其他土地利用方式下，从60 cm处开始土壤含水量出现明显的水分活跃层分界点。(3)不同土地利用方式下降雨特征因子与表层土壤含水量的关联性都最小，与中间层和深层土壤含水量的关联性都较高；4种土地利用方式中相对于裸地，林地、草地和农地对土壤水分的调控作用较...

Impact of Individual Rainfall on the Changes of Soil Water Content in Deep Layer of Different Land Uses

[Objective]Water resources are shortage in the Loess Plateau. Exploring the impact of the individual rainfall on the change of soil water content in different land uses is of great significance to the theoretical exploration of the optimal allocation of regional water resources. [Methods] Based on the measured data of natural rainfall in runoff field of Nanxiaohegou in Qingyang, Gansu Province, and the observed data before and after rainfall under four land use patterns(agriculture, forest, grass and bare), the characteristics of soil water content changes in five different rainfall levels under different land use patterns were analyzed. [Results](1)The dynamic change of soil water content is closely related to land use pattern. Among the four land use patterns, forest land has better water storage capacity than bare land, but the soil water content in bare land fluctuates the most under different rainfall levels. With the increase of soil depth, the response of surface soil moisture to rainfall is obvious, and there is a certain lag between the middle layer and the deep layer.(2)Under specific rainfall conditions, the water exchange at different depths of soil has obvious demarcation point of water active layer. Under heavy rain and rainstorm conditions, there is an obvious demarcation point of water active layer at 40 cm depth. Under moderate rain conditions, except for the significant difference in soil water content after rain, under other land uses, soil water content appeares obvious demarcation point of water active layer from 60 cm.(3)Under different land use patterns, rainfall characteristic factors had the lowest correlation with surface soil water content, but had the highest correlation with middle and deep soil water content. Compared with bare land, forestland, grassland and agricultural land have the greater regulation effects on soil water. [Conclusion] The difference of soil infiltration response to rainfall under different land use patterns is closely related to the distribution of surface vegetation cover and underground vegetation root system. The gray correlation analysis of soil moisture changes provides the theoretical basis for the study of soil and water conservation in the Loess Plateau.