SPEI-based analysis of spatio-temporal variation characteristics for annual and seasonal drought in the Zoige Wetland, Southwest China from 1961 to 2016

摘要

Water scarcity has a destructive impact on the social and economic development around the world. The present study investigated the variations of drought conditions during 1961-2016 in the Zoige Wetland of Southwest China by adapting the Mann-Kendall (MK) analysis, the Theil-Sen slope estimator, continuous wavelet transforms (CWT), and the inverse distance weighting (IDW) algorithm. The partial correlation coefficient (PC) was also used to understand the causes of Standardized Precipitation Evapotranspiration Index (SPEI) characteristics from different climate factors. The results showed that the majority of the wetland had a drying trend with a - 0.142/(10 years) rate of SPEI on annual scale, while a 2-8-year significant period was observed on both annual and seasonal scales. In spring, the wetland presented dryness and had a tendency of mitigation except for the northeastern area. In summer, the wetland mainly presented humidity, but it had a drying trend except for the southern area. In autumn, the overall wetland was humid with an abrupt change towards dryness occurring around 1983 and the whole wetland showed a manifest drying trend. In winter, most areas showed drought while the Jiuzhi County and part of the southern wetland had an alleviating trend of drought. The decrease of annual SPEI was primarily due to the decrease in precipitation, the mean temperature increase, and relative humidity decrease that offset the reversed impact of wind speed decrease and sunshine duration decrease. The change of SPEI on a seasonal scale was the consequence of the significant change in precipitation only in winter. The results of this study would be of use for understanding the characteristics of climate variation and water resources management across the Zoige Wetland in a changing environment.