毛乌素沙地土壤水分日动态变化分析

Soil Moisture Date Dynamic Change of Different Moisture Content Gradient and Its Influence Factor Analysis in Maowusu Sand Land

依据各水分梯度垂直层之间水分运动方式以及与气象因子的关系，将沙丘分为3种水分梯度类型：无地下水补给梯度（沙丘顶部、中坡）、地下水补给临界梯度（下坡）、地下水补给梯度（丘间低地）；无地下水补给梯度，降雨能够改变某一层在整个垂直水系统中的功能作用，这个调节层深度不确定，主要与降雨强度、降雨历时及土壤渗透速度有关系；地下水补给临界梯度（下坡）是受地下水影响的临界点，该水分梯度1000mm土壤含水量与其它土壤层均为负相关，同温度为负相关（R^2=0．703，P〈0．01），与湿度正相关（R^2=0．780，P〈0．01）；100～600mm之间呈正相关。与温度呈正相关，与湿度负相关；地下水补给梯度（丘间低地）各垂直层之间均为正相关。与温度呈负相关，与湿度正相关；土壤含水量日动态变化有时滞效应，16：00土壤含水量值最小，滞后于温度最高值的时间，16：00之后土壤含水量逐渐升高。但是由于土壤水分的运动和散失，多数垂直层土壤含水量比06：00低。

On the relationship between the way of each vertical moisture contents changed and the meteorological factors, the sand dunes were divided into three kind of moisture contents gradients type： nonground water supplies gradient（sand dune crown, center slope）, ground water supplies critical gradient （downhill）, ground water supplies gradient（between earthen mound lowly）, non-ground water supplies gradient. Rains can change the function of a layer in the entire vertical aqueous system. This adjustment level depth was indefinite, mainly responded with the rainfall intensity, rainfall duration and the soil infiltration speed; the ground water supplies critical gradient is the ground water influence critical point; the moisture content gradient in 1000 mm soil moisture content and other soil levels are negative correlated,the same temperature is also negative correlation（R^2=-0. 703, P〈0.01）. Is being positive correlated to the humidity（R^2=0. 780, P〈0.01）. Between 100-600 mm presents were positive correlated. Presents the positive correlation with the temperature, negative correlation with humidity. The ground water supplies of each vertical level for is positive correlated, negative correlated with the temperature and the humidity. The soil moisture content date dynamic change has time lag effect. The soils moisture contain was the smallest in 16： 00, Lag to the temperature maximum time. After 16： 00, the soils moisture contain increased gradually. But because the soil moisture movement and dissipation, the most vertical levels soil moisture content is lower than 06： 00.