Standardized precipitation evapotranspiration index shows drought trends in China
Standardized precipitation evapotranspiration index (SPEI), calculated from the difference between potential evapotranspiration and precipitation, showed dry and wet deviations from normal conditions. This is generally used as an indicator for drought evolution trends in drought assessments, water resources management and other fields of hydrology. Using monthly mean surface air temperature and precipitation collected from 160 meteorological stations across China for 1951—2009. Spatial distributions of seasonal drought trends and frequencies of extreme drought events were analyzed via SPEI. The results showed drying trends across the whole of China. The most significant drought was in the west, north and northeast of China. It was, however, wet in some regions of northern Xinjiang and the border regions of Sichuan and Yunnan. Drying trends existed for all four seasons, and were more obvious in spring and autumn. Summer was always dry in the last 15 years, although with a drying trend insignificant at the 0.05 level. Furthermore, the frequency of extreme drought increased significantly. Significant trends in temperature increase along with moderate trends in precipitation decline were noted for many stations in the northeast and north of China. The combined effects of precipitation and temperature caused significant droughts in the country. In the Sichuan Basin, precipitation significantly decreased with no significant change in temperature. Drought in Sichuan Basin was largely attributed to decreasing precipitation. In recent years, extreme drought events increased with decreasing frequencies of precipitation events in many areas of China. Widespread drought trends and significant increases in extreme drought events probably hindered China's economic development. SPEI-detected drought trends were mostly consistent with observed droughts in China, indicating that SPEI was an ideal index for monitoring drying trends.
国家科技期刊平台
NSTL
万方数据
维普
