Long-term trend of major climate variables in the Taihu basin during the last 53 years

摘要

Recently, frequent occurrence of extreme flood events associated with the hydrological cycle accelerated by climate change in the Taihu basin have received significant attention by both local and central governments in China. Detection of the plausible long-term trend for climate variables is the first step to understand the effects of climate change on floods. On the basis of monthly time series of precipitation, mean air temperature, relative humidity and sunshine duration in the Taihu basin from 1954 to 2006, the spatio-temporal patterns of long-term trend for these climate variables during the past 53 years were detected and analysed by using the nonparametric Mann-Kendall test and departure curve method. The results showed that the mean air temperature increased by 1.43° in the Taihu basin during the past 53 years, and the annual mean precipitation increased by 10.44 mm with more temporal and spatial variability, while the annual mean relative humidity and annual sunshine duration exhibited a decreasing tendency, with 10-year decreasing rates of -0.99% and -7.797 h, respectively. In addition, the Hurst index was adopted to detect the long-range dependence for the time series of these climate variables, which showed that the annual mean precipitation in the Taihu basin would continue to increase in the future, similar to the trend of mean air temperature, whilst the annual mean relative humidity and annual sunshine duration would continue to decrease, being consistent with that for the last 53 years. The results of this study could be used to provide technical support for flood control and drought relief in urban planning and construction under future global climate change in the Taihu basin.