宁夏中部干旱带生态恢复对沙尘暴的降频与减灾潜力分析

An analysis of the potential impacts of ecological restoration on frequency and disaster reductions of sandstorm in the arid regions of the middle Ningxia

利用宁夏1971～2000年常规气象、自记风及同期亚洲环流资料,并结合1990～2000年宁夏八大类土地详查资料,建立了对宁夏中部干旱带春季3～5月份沙尘暴发生频次和平均持续时间拟合效果较好的生态/气候影响分析模型.通过对不同生态背景与气象条件下沙尘暴发生频次及平均持续时间的分类对比分析,基本摸清了产生沙尘暴的气象和生态因子间的量化对应关系.结果证实:在生态环境局部治理、整体退化背景下,20世纪70年代以来,宁夏沙尘暴起暴阈值随年代际显著下降、沙尘暴平均持续时间明显延长,沙尘暴发生机率随年代际显著提高、危害加大.揭示了20世纪80年代中期以来沙尘暴发生频率的降低主要由气候变暖、冷空气活动频次减少造成;但在生态退化显著、沙尘暴高频区宁夏盐池、同心一带,同等动力条件下,沙尘暴平均持续时间的显著延长则主要是由于生态退化所致.即在宁夏中部干旱带,生态环境的恢复与改良,对减少沙尘暴发生频次、尤其是降低沙尘暴平均持续时间及减轻沙尘暴灾害具有显著的生态调控潜力.

Using the conventional meteorological and anemometer data and the Asian circulation data from 1971 to 2000, as well as the 8-type land use data from 1990 to 2000, an ecological/climatic effect model of sandslorm occurrence frequency and mean duration was established for the spring from March to May in Ningxia region. By carrying out comparison and cluster analysis on the frequency and duration of sandstorms, under different ecological and meteorological conditions, a quantitative relationship between meteorological and ecological factors that result in sandstorms was revealed . The results show that, with the ecological environment being locally improved but degraded as a whole, since the 1970s the threshold of sand flying has been decreasing, the mean duration and frequency of sandstorms have been significantly increasing, and sandstorm damage became more and more severe. Since the middle 1980s, the overall decrease of the sandstorm frequency was resulted from the climate warming and a reduction of cold air activities. However in the area of Yanchi-Tongxin, where the sandstorm frequently occurred and the ecology severely degraded, the ecological degeneration was a major cause of the duration of sandstorms, suggesting that, in the areas with frequent sandstorms, the improvement and augmentation of mean restoration of ecological environment have eminent potential impacts on the reductions of sandstorm frequency and, in particular, mean duration, as well as on the disaster reducing.