Temporal and spatial evolution characteristics and influencing factors of historical flood disasters in Xizang
The reconstruction of natural disasters on a long time scale is of great significance to under-standing the evolution process of disasters on the Qinghai-Tibet Plateau.Through data mining and collec-tion both in the past and at ghe present,this paper reconstructed the flood disaster in Xizang from 1800 to 2010,and analyzed the spatial and temporal distribution characteristics and the influencing factors of flood disaster.The results show that:(1)371 floods occurred in Xizang in recent 210 years,with an average fre-quency of 1.77 floods/a,which is similar to that of the neighboring Sichuan Basin,and mainly concentrat-ed in summer.The frequency has shown an obvious upward trend,and there are five shock cycles,5a,10a,15a,30a and 50a,among which the shock cycles of 10a,30a and 50a are the strongest.(2)The flood disasters in Xizang are mainly distributed in the"one river and two rivers"and the river basins in southern Tibet,with Lhasa,Shannan,Shigatse and Nyingchi as the core areas.The spatial migration of flood disas-ters in the concentrated time period is mainly in the southeast direction.The spatial distribution is the strongest in June,and the concentration is scattered in August.(3)Comprehensively analgsis of the main causes of flood disasters in Xizang.From 1800 to 2010,flood disasters in Xizang were mainly concentrated in southeast Xizang,which were strongly related to the causes of river density and precipitation,etc.Flood disasters are meteorological,so in-depth analysis of climate change will be introduced into future research.
historical flood disastersgravity modelellipse of standard deviationperiodic variation
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