北京市怀柔区琉璃庙镇泥石流发育特征及监测预警

Developmental characteristics and monitoring and early warning of debris flow in Liulimiao Town of Huairou District,Beijing

怀柔区琉璃庙镇位于北京市北部山区,是北京山区泥石流的高发区之一,镇内共有泥石流72处,是怀柔区泥石流数量最多的乡镇。该镇泥石流多发育于中—低山区,均为暴雨-沟谷型泥石流,规模以中—小型为主,发育特征具有流域面积小、相对高差大、主沟曲线长度相对较小、主沟弯曲系数中等偏下、流域切割密度中等偏上、主沟纵坡偏大、山坡平均坡度偏大和物源量大的特点,经量化打分综合判定易发性属中—低易发。泥石流的形成受地形、物源及降雨因素影响,即有利的地形、充足的物源及突发的水力条件,三者缺一不可。监测预警是未来泥石流灾害防治的有效手段,但现阶段预警为区域性的,预警精度偏低,建议结合泥石流的发育特征,对重要的泥石流沟开展单沟预警,加强预警阈值研究,提高泥石流灾害预警的精度,实现精准有效的预防。

Liulimiao Town,Huairou District,located in northern Beijing,is one of the mountainous areas with high incidence of debris flow in Beijing.There have been 72 debris flows,making it the township with the largest number of debris flows occurrences in Huairou District.Debris flows in this area are mostly developed in medium to low mountainous areas,all of rainstorm valley types,and mainly at medium to small scales.The development of the debris flows here are characterized with small watershed area,large relative elevation difference,relatively small curve length of main gully,medium to low bending coefficient of main gully,medium to high cutting density of watershed,large longitudinal slope of main gully,large average slope of hillside and large amount of material sources.Through quantitative scoring,it is comprehensively determined that the susceptibility in Liulimiao is medium to low.The formation of debris flow is affected by three factors:terrain,material source and rainfall,namely favorable terrain,sufficient material source and sudden hydraulic conditions.Monitoring and early warning is an effective means of debris flow disaster prevention in the future,but at this stage,early warning is regional with low accuracy.To realize accurate and effective prevention and improve the accuracy of debris flow disaster early warning,it is suggested to carry out single ditch early warning for important debris flow gullies and strengthen research on early warning thresholds according to the developmental characteristics of debris flows.