八宝河流域土壤水时间稳定性及其下垫面控制因素分析

An Analysis of Soil Moisture Temporal Stability and its Controlling Factors of Underlying Surface in Babaohe Watershed

时间稳定性概念体现了土壤水分的空间结构随时间具有持续稳定的特性,由此找到的代表性点其测量结果可用于反映流域平均土壤水分状况,此方法为流域尺度的土壤水分估算带来便利。本文围绕黑河上游八宝河流域开展表层土壤不同深度的土壤水时间稳定性特征分析,寻找能反映流域表层土壤水分平均状况的代表性点,结合流域土壤、植被、地形条件,研究流域内土壤水空间结构时间稳定性的主要控制因素。结果表明:八宝河流域代表性点多位于优势植被与主要土壤类型分布区域,在埋深4 cm处为23号、13号,10 cm处为47号、20 cm处为37号,时间稳定性在垂直方向随深度增加;植被覆盖类型和土壤类型是该流域表层土壤水时间稳定性的主要控制因素,在高寒禾草、苔草草原,棕黑毡土覆盖区域观测,更易于获得深度10 cm以上土壤水平均状况。本研究可为流域尺度的土壤水分估算提供理论参考,为优化设计流域土壤水观测网络提供科学依据。

The concept of temporal stability embodies the spatial pattern of soil moisture persist with time.Hence,measurements at the representative points can reflect the mean soil moisture of the watershed.This method facilitates the estimation of soil moisture at watershed scale.This paper analyzes the characteristics of soil moisture temporal stability at different depths in Babaohe Watershed in the upper reaches of Heihe River.The representative points to reflect the mean-watershed soil moisture are located.Then combining the soil,vegetation and topographic conditions of the watershed,the key factors that control the temporal stability of spatial soil moisture distribution are investigated.The results show that most of the representative points are located at the area covered by dominant vegetation and main soil type.The representative points in Babaohe Watershed are No.23 and 13 at the depth of 5 cm,No.47 at the depth of 10 cm,and No.37 at the depth of 20 cm.The temporal stability increase with the depth in the vertical direction.The main controlling factors of the soil moisture temporal stability in this basin are the vegetation and soil type.In the area covered by the alpine grass and carex steppe,and brown and black felt soils,it is easier to obtain the average surface soil moisture above the depths of 10 cm.This study can provide a theoretical reference for the soil water estimation at watershed scale,and a scientific basis for optimizing the design of observation network of watershed soil moisture.