长江流域土壤相对湿度变化及其影响因素

以1992~2012年长江流域196个土壤观测站的旬土壤相对湿度资料为基础,通过线性趋势和Kriging插值等方法分析0~50 cm土层土壤相对湿度年际、年内时空分异和季节变化特征,并从气候和NDVI要素探寻其变化原因。结果表明:(1)长江流域年均土壤相对湿度自1992年以来整体上呈波动增加趋势,年际变化倾向率为0.26%/a。江源地区土壤相对湿度增幅大于其他地区。(2)土壤相对湿度表现为东南和西南部较高,东北和西北部较低的空间分布特点。(3)四季土壤相对湿度增加的强烈程度由大到小依次是秋季、冬季、夏季、春季。(4)土壤相对湿度增加的主要原因是潜在蒸发减少和NDVI增加。

CHANGES OF SOIL RELATIVE MOISTURE CONTENT AND INFLUENCING FACTOR IN THE YANGTZE BASIN DURING 1992-2012

This study is based on the ten days' soil relative moisture data of 196 observation stations in the Yangtze Basin from 1992 to 2012,using the Kriging interpolation method to explore the spatial and temporal distribution and seasonal variation characteristics of soil relative moisture contents in 0-50 cm soil layer depths in the Yangtze River Basin.Moreover,the reasons for soil relative moisture content changes were explored mainly from climatic factors and NDVI.The results showed that:1) the soil relative moisture content in the Yangtze River Basin has been increasing since 1992,with a rate of inter-annual variation tendency of 0.26％/a.2) the soil relative moisture content was higher in the southeast and southwest than in the northeast and northwest.3) the increasing intensity of soil relative moisture content showed an order of spring ＜ summer ＜ winter ＜ autumn.4)The main reason for the increase of soil relative moisture content were decreased potential evaporation and increased NDVI in the Yangtze River Basin.