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土壤水分影响因子的尺度差异及作用是其尺度依赖性研究的基础.本文以青藏高原拉萨河流域耕地土壤为对象,通过遥感影像分析和野外调查,在全流域和小流域尺度上分别布设样点115和49个,采用土钻法分3层(0~20、20~40、40~60 cm)抽取土壤样本,获取土壤水分含量,然后运用生态学冗余分析和统计分析,筛选出影响耕地土壤水分的主要因子.结果表明:在全流域尺度,受气候、海拔影响,土壤水分呈西南-东北递增趋势,其中,河谷区耕地受河流侧渗补给影响,下层土壤水分高于上层;在小流域尺度,耕地土壤水分随海拔升高及坡度增大而减少,土壤贮水能力随石砾含量增多而减弱.研究结果为拉萨河流域耕地向高海拔扩张、作物结构调整、土地整理及灌溉设施布设提供了重要依据.
The scale differences and their effects on soil moisture are the basis of their scale-dependent studies.In this paper, the cultivated land soils of the Lhasa River basin in the Qinghai-Tibet Plateau are used as objects to analyze the spatial distribution of soil moisture in the whole basin and small watershed by remote sensing image analysis and field survey 115 and 49 soil samples were collected by soil drilling method in three layers (0-20, 20-40, 40-60 cm) to obtain soil water content. Then, using ecological redundancy analysis and statistical analysis, The results showed that in the whole basin scale, influenced by climate and altitude, the soil moisture showed an increasing trend from southwest to northeast, in which, the arable land in the valley was affected by the infiltration of rivers and the soil moisture in the lower layer was higher than that in the upper layer. At the catchment scale, the soil moisture of cultivated land decreased with the increase of elevation and slope, and the storage capacity of soil decreased with the increase of the content of gravel.The results showed that the cultivated land in Lhasa River valley expanded to high altitude, the structure of crops, land consolidation and irrigation facilities Layout provided an important basis.