气候变化情景下泥石流危险性响应分析

通过中国1950—2010年降水日值0.5°×0.5°格点数据和CMIP5的6个气候模式数据,以2010年舟曲8·7特大山洪泥石流为例,估算此次灾害发生的降雨重现期,并估算未来同等重现期下的降雨量,基于HEC-HMS和FLO-2D模型模拟该降雨量下山洪泥石流堆积面积与泥沙冲出量,进而得到了气候变化背景下的泥石流危险性变化。结果表明：2010年舟曲8·7山洪泥石流灾害的降雨重现期为1500 a,未来相同重现期下降雨量为113.7 mm。设防水平不变条件下,舟曲县城泥石流堆积面积可达2010年灾害的173%,总泥沙量增加到148%,且泥石流堆积面积增加的区域主要位于2010年舟曲县城人口密集区。可见,灾后重建中舟曲县城一半以上居民的转移安置政策有利于弱化未来气候变化背景下泥石流危险性增加的不利影响,是一种有效的气候变化适应性举措。

Analysis of the changes in debris flow hazard in the context of climate change

Based on the 0.5°×0.5° grid daily precipitation datasets and six climate model simulation results of CMIP5, taking the 2010 Zhouqu flash flood and debris flow disaster as the study case, the precipitation return period of this disaster was estimated, and the future precipitation at the same return period was inferred. Then, using the HEC-HMS and FLO-2D models, the mudflow deposition areas and total sediment amount under the future precipitation were simulated, and then the variation of the debris flow hazards was presented. The results show that the precipitation return period in the 2010 Zhouqu debris flow disaster is 1500 years, and the estimated future precipitation for the same return period is 113.7 mm. Under the same fortification, this precipitation will cause the debris flow deposition area in Zhouqu county town to reach 173% of that in 2010 Zhouqu debris flow, and the total amount of sediment will increase by 148%. In addition, the increased area of the debris flow is mainly located in the densely-populated area of Zhouqu county town in 2010. It can be said that the policy of relocating more than half of the residents in Zhouqu county town during the 2010 post-disaster reconstruction, is conducive to preventing the adverse effects of increased hazard of debris flow in the context of climate change.