陕北黄土区不同微地形土壤水分变化趋势分析

目的我国黄土高原地区干旱少雨、蒸发性强，降雨成为当地土壤水分的主要来源，而黄土坡面微地形对降水进行二次分配，因此研究不同立地类型的微地形土壤水分的动态变化趋势，可以为困难立地类型的微地形的植被生长和恢复提供参考依据。方法本文选择缓台、塌陷、陡坎、切沟和浅沟5种微地形的土壤水分为研究对象，于2010年8月至2013年6月在吴起县合沟流域阳坡上的定位观测数据，利用自相关检验、Mann-Kendall趋势检验、线性回归等方法，分析研究5种微地形0~160cm各土层土壤水分动态变化特征。结果在检测期间的全年和生长季中，微地形的土壤含水量随深度的增加呈现增大的趋势，其中切沟的土壤含水量相对较高，陡坎最低。各土层的土壤水分存在显著的正自相关性；5种微地形土壤水分在检测期间的变化趋势均不显著，其中塌陷的土壤水分在各土层均有微弱增加的趋势，其他4种微地形的土壤水分在各土层的变化趋势均有增有减；缓台、塌陷、陡坎、切沟和浅沟5种微地形在观测期间的变化速率也有差异，相对而言塌陷的土壤水分变化速率最快。结论综合分析可得，在监测期间，切沟的土壤含水量最高，但塌陷的增长速率较快。 

Dynamic changing trend of soil moisture in different micro-topography in loess region of northern Shaanxi Province of northwestern China

[ Objective ] In the Loess Plateau of northern China, rainfall is the main source of soil moisture due to limited amount of precipitation and strong evaporation. In the loess hillslope, rainfall would be reallocated depending on microtopography, that would affect soil water variation. Therefore, our study aimed to analyze the dynamics of soil moisture in different microtopography types, which can provide reference for the vegetation growth and restoration. [ Method] In this paper, soil moisture in the five microtopography types, e. g. platform, collapse, scarp, gully and shallow gully, was investigated in sunny slope of Hegou Catchment of Wuqi County, Shaanxi Province of northern China from August 2010 to June 2013. The self-correlation test, Mann-Kendall trend test, linear regression methods, etc. , were used in this study. [ Result] During the whole year and the growing season in the investigation period, the soil moisture content of microtopography increased with the increasing depth. Among them, the soil moisture content in the gully was relatively high, and in the scarp was the lowest. There was a significantly positive autocorrelation between soil moisture in each soil layers. The dynamics of soil moisture in the five micro-topography types during the investigation period was not significant. The soil moisture in each soil layer in the collapse had a slightly increasing trend, however, the soil moisture in other four microtopography types increased or decreased in each soil layer. The differences in changing rate of five microtopography types were also observed. [ Conclusion ] Overall, during the monitoring period, among the five microtopography types, the soil moisture content in the gully was the highest, but the increasing rate of collapse was quicker.