50 a来宁夏可利用降水的时空变化及其对生态环境的影响

 利用1955—2006年宁夏气温、降水资料, 计算了水分资源各分量,并结合1982—2003年植被指数(NDVI)值,分析宁夏水分资源各分量的变化及其对生态环境的影响。结果表明:宁夏水分资源各分量时空分布极不均匀,夏季最大,冬季最小,南部较北部水分资源相对丰富；50 a来降水和可利用降水呈下降趋势,蒸发呈上升趋势,各分量大体经历了4个变化阶段；四季中秋季可利用降水的突变特征最明显,突变年在1978年,突变后各地区可利用降水明显减少,中部干旱区最明显；水分资源各分量有明显的16 a、8 a和4 a左右的周期变化。近20 a宁夏植被覆盖率整体得到提高,进一步分析表明,宁夏大部NDVI值的变化与自然环境和水分资源密切相关。

Spatial-temporal Changes of Available Precipitation for 50 Years in Ningxia and Its Effect on Environment

Each variable component of water resources in Ningxia was calculated based on the precipitation and temperature data from 1955 to 2006, which combined with the NDVI data from 1982 to 2002 the effect of water resources variation on eco-environment was analyzed. The spatial-temporal distribution of each variable component of water resources in Ningxia was much asymmetric; it was the largest in summer and the smallest in winter, and the more abundant in south than that in north. In recent 52 years, precipitation and available precipitation in Ningxia showed a downtrend, and the evaporation showed an uptrend; each variable component experienced four variational stages on the whole. The saltation characteristic of available precipitation was most remarkable in autumn and the saltation year is in 1978, after the saltation the available precipitation reduced evidently especially in the middle arid area. Each variable component has remarkable changing periods of 16a, 8a and 4a. In recent 20 years, the vegetation coverage rate was improved, and more analysis showed that the variation of NDVI value in Ningxia closely related with natural environment and water resources.