Mechanisms and spatiotemporal variation characteristics of flooding over northwestern China
The physical geography and hydroclimatic conditions in the arid region of in northwestern China leading to diverse flood-generation mechanisms.Under the influence of global and regional climate change,the spatiotemporal variation of floods and flood-generation mechanism in this region is still unclear and restricts flood prevention and mitigation and the implementation of the Belt and Road Initiative in the major regions.Based on the series of the annual maximum flood peak discharge in 58 river basins in the study area from 1961 to 2017,we analyzed and revealed the mechanisms,spatial distribution and interannual variation characteristics of flood in the basin in the past 60 years based on statistical tests and machine learning approaches.The results show that the frequency of extreme floods and the annual maximum flood peak discharge magnitude are increasing,with the maximum increase in the frequency of extreme floods at about 0.84 times/10 years,and the maximum increase in the annual maximum flood peak discharge magnitude at about 29％/10 years compared with the multi-year average,and the largest increase is mainly observed in the eastern Tianshan Mountains and the Qilian Mountains.There are three main flood generation mechanisms,i.e.,rain(R),snow(S)and mix(M),the frequency of R and M floods increased significantly,while the frequency of S floods decreased.The contribution of flood mechanisms transformation to the increase of annual maximum flood peak discharge magnitude can reach up to 38％,which is significantly higher than the contribution of a single hydrometeorological factor such as precipitation.The results of this study emphasize the importance of attributing and predicting the changes of flood characteristics in geographically complex region from the perspective of flood mechanisms.Engineering hydrological design in the changing environment also needs to consider the influence of the heterogeneity of flood samples caused by different flood mechanisms on the flood frequency analysis,so as to provide scientific support for flood risk management and response in the basin.
floodflood generation mechanismspatiotemporal variationattributionnorthwestern China
万方数据
维普
