The impact of climate change on extreme runoffs in the Tianshan region: Taking Kaidu River as an example

Abstract

【Objective】 Climate change is anticipated to lead to increased frequency of extreme weather events such as droughts and floods, which have significant implications for water availability in catchment areas. In this paper, we analyze extreme runoff events in the Tianshan region in northwestern China and their correlation with climate change. 【Method】 The analysis was based on data measured over the past 60 years from the Kaidu River Basin in the region. The variation in its runoff events was analyzed using the Sen slope, MK test, Pettitt test and probability distribution function, coupled with the SWAT model and the GCM model. 【Result】 ① Annual runoff and seasonal runoff, except in spring in which the runoff has seen a significant increase, in the basin have been increasing, albeit not at significant levels. Runoff changes are correlated to precipitation more than to temperature. ②Over the past 60 years, frequency, intensity and duration of extreme runoff events have been increasing, and there is a delay in the occurrence of the first flood in each year. ③ The Log-Pearson3 function is optimal for modelling extreme runoff events. The returning times of floods was 50 years, the maximum duration of flooding events and average peak flow rate of floods were 7.09 times, 79.04 days and 180.04 m3/s, respectively. ④ Under projected climate change scenarios, the frequency of flooding events will increase, average annual maximum flow rate in the floods will amplify, maximum duration and average duration of floods, as well as average intensity of floods will all increase. The first flooding in each year will arrive early, and extreme runoff intensity is the highest under the SSP245 scenario and the lowest under the SSP370 scenario. 【Conclusion】 Climate change significantly influences extreme runoff events in the Tianshan region, resulting in increased frequency and severity of both extreme runoff events and single large flood. These findings have important implications for improving management strategies to mitigate the adversary impact of extreme weathers induced by climate changes.

Keywords

• climate change
• extreme runoff
• swat model
• tianshan
• kaidu river