The Debris Flow and Its Controlling Measures of Ruobixiao Gully in the Upper Reaches of Qingyi River of Sichuan Province

Ruobixiao gully in the left bank is one of the first tributaries in the upper reaches of Qingyi River of Sichuan province.It has a drainage area of 5.06 km2,and a total length of 3.56 km.Geological,geomorphologic,and climatic features of the Ruobixiao Gully are presented in this paper.The drainage develops in the eastern slope of the Jiajin mountain area,where the precipitation is very concentrated from May to October accounting for 85～90% of the year,the maximum daily precipitation is 119.1 mm.Therefore,the composition of landform,geology and rainstorm provides favorable conditions for the burst of debris flow.The damage of debris flow in this gully is potential.Through field observation,the characteristic of the debris flow in Ruobixiao Gully can be described as turbulatent～cambic.The density of the gully is 2.0 t/m3,1.9 t/m3,1.8 t/m3 for debris flow of P=1%,2%,5% respectively.The debris flow type of the gully can be defined as middle frequency-middle～large scale-low～high viscosity.The major activity characteristics of debris flow are as follows:(1) The loose solid material for debris flow is mainly supplied by the slope landslip;(2) The debris flow causes rapidly disaster and strong damage;(3) Middle frequency.Debris flow has three development tendencies in this gully,if unreasonable activities of human cease,and the comprehensive controlling measure work,debris flow will become weak.The engineering plans for disaster relief are put forward.After adopting the block,bed stabilization,diversion measures,the damage of debris flow can be mitigated.