基于流域形态特征分析的北京北山泥石流易发性评价因子研究

Study on evaluation factors of debris flow susceptibility based on the analysis of watershed morphological characteristics in Beishan Mountain of Beijing

传统泥石流易发性评价关键依赖于专家现场判别经验的归纳总结。影响一次泥石流过程的三大因素15个指标中存在不可量化指标、难以量化指标和可量化指标混合评价的问题。为了消除易发性评价主观打分、数据置信度低的影响,开展了基于自然沟道本底因素的可量化指标与泥石流易发性规律分析探讨。以怀柔区怀北镇大沙河流域泥石流隐患作为样本,探讨流域形态特征与泥石流易发性的相关性。初步采用数据获得性好、置信度较高的流域面积、形状因子和沟道纵比降等可量化指标进行数据分析。通过数据拟合方法建立了反映沟道流域形态特征的综合因子F_(g),基于沟道系统参数F_(g)和物源系统参数A_(dl),提出泥石流易发性因子I_(s)。

The key to the traditional debris flow vulnerability assessment depends on the summary of experts'on-site discrimination experience.Among the 15 indicators of the three major factors influencing a debris flow process,problems exist with the mixed evaluation of non quantifiable indicators,difficult quantifiable indicators and quantifiable indicators.In order to eliminate the impact of subjective scoring and low data confidence in vulnerability assessment,this paper studies the quantitative indicators based on natural gully background factors and debris flow vulnerability laws.Taking the hidden danger of debris flow in Dasha River basin in Huaibei Town,Huairou District as an example,the correlation between the morphological characteristics of the basin and the vulnerability of debris flow is analyzed.Preliminary data analysis has been carried out of quantifiable indicators such as drainage area,shape factor and channel longitudinal gradient with good data availability and high confidence.The comprehensive factor F_(g) reflecting the morphological characteristics of gully watershed is established by the data fitting method,and based on the gully system parameter F_(g) and the material source system parameter A_(dl),the debris flow vulnerability factor I_(s) is put forward.