Critical Rainfall Patterns for Rainfall-induced Debris Flows in the Wenchuan Earthquake Area

doi:10.19657/j.geoscience.1000-8527.2018.03.20

Abstract

Abstract:

To obtain the rainfall characteristics and enhance the early warning system for rainfall-induced debris flows, the post-debris flow rainfall data in the Wenchuan earthquake area are collected, and the rainfall intensity and early-stage effective accumulative rainfall are analyzed. The results show that the rainfall-induced debris flows in the study area can be classified into three types, i.e., short-term rainfall, persistent rainfall and intermittent rainfall. The main differences among the three rainfall types occur in the rainfall intensity, duration and effective accumulation, which can result in different soil percolation, saturation, and erosion mechanisms in provenance for debris flow initiation. Critical rainfall intensities and effective accumulative rainfall could be related to critical rainfall types. The short-term rainfall type may be associated with the highest rainfall intensity and the least effective accumulation;persistent rainfall type is associated with medium rainfall intensity and the most effective accumulation, whilst the intermittent rainfall type can be related to the lowest rainfall intensity and the medium effective accumulation. After a verification for the sudden collapse induced by the high-mountain-formation debris flows in Xinmo Village of the study area, the result showed that the prime reason was the decrease of rock shear strength caused by long-term intermittent rainfall.This work provides scientific basis for the early warning system for debris flows in the Wenchuan earthquake area.

Key words: rainfall-induced debris flow, critical rainfall pattern, critical rainfall intensity, effective accumulative rainfall

CLC Number:

P642.2

CHANG Ming, DOU Xiangyang, FAN Xuanmei, YAO Cheng. Critical Rainfall Patterns for Rainfall-induced Debris Flows in the Wenchuan Earthquake Area[J]. Geoscience, 2018, 32(03): 623-630.

Figures/Tables 6

References 23

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编号	泥石流暴发地点	降雨时间	前期降雨有效持续时间/h	激发雨强/ (mm/h)	前期有效累计雨量/mm	激发雨型
1	汶川县映秀镇岷江流域	2010-08-14	13	16.6	111.2	长期间断降雨型
		2011-08-21	7	56.5	125.8	中期持续降雨型
		2013-07-11	76	6.4	111.4	长期间断降雨型
2	绵竹市清平乡绵远河流域	2010-07-31	1	50.4	89.5	短期突然降雨型
		2010-08-13	6	37.4	82.6	中期持续降雨型
		2010-08-19	6	31.9	121.6	中期持续降雨型
		2013-07-10	34	19.2	123.5	长期间断降雨型
3	北川县擂鼓镇苏宝河流域	2008-09-23	3	33.5	82.7	短期突然降雨型
3	北川县擂鼓镇苏宝河流域	2008-09-24	10	41.8	163.1	长期间断降雨型
4	都江堰龙池镇龙溪河流域	2010-08-13	2	75.0	97.0	短期突然降雨型
4	都江堰龙池镇龙溪河流域	2010-08-18	8	69.0	183.8	中期持续降雨型
5	彭州市龙门山镇白水河流域	2012-08-18	2	72.0	112.0	短期突然降雨型

编号	泥石流暴发地点	降雨时间	前期降雨有效持续时间/h	激发雨强/ (mm/h)	前期有效累计雨量/mm	激发雨型
1	汶川县映秀镇岷江流域	2010-08-14	13	16.6	111.2	长期间断降雨型
		2011-08-21	7	56.5	125.8	中期持续降雨型
		2013-07-11	76	6.4	111.4	长期间断降雨型
2	绵竹市清平乡绵远河流域	2010-07-31	1	50.4	89.5	短期突然降雨型
		2010-08-13	6	37.4	82.6	中期持续降雨型
		2010-08-19	6	31.9	121.6	中期持续降雨型
		2013-07-10	34	19.2	123.5	长期间断降雨型
3	北川县擂鼓镇苏宝河流域	2008-09-23	3	33.5	82.7	短期突然降雨型
3	北川县擂鼓镇苏宝河流域	2008-09-24	10	41.8	163.1	长期间断降雨型
4	都江堰龙池镇龙溪河流域	2010-08-13	2	75.0	97.0	短期突然降雨型
4	都江堰龙池镇龙溪河流域	2010-08-18	8	69.0	183.8	中期持续降雨型
5	彭州市龙门山镇白水河流域	2012-08-18	2	72.0	112.0	短期突然降雨型