Prediction of Debris Flow Occurrence in Jiuzhui Gully Based on Field Investigation

Abstract

Jiuzhui gully is located in the Jiexu hydropower station project area, where the debris flow in Jiuzhui gully poses a great threat not only to the construction process, but also to the future operation. With the aim of reducing the risk of disaster caused by debris flow in Jiuzhui gully watershed, we conducted a systematic field investigation to obtain the basic data of this basin. In addition, remote sensing interpretation was employed to identify the area and location of source materials. By means of field investigation, the fundamental data of the whole basin can be acquired, including the topography, angles of the slopes, rainfall conditions, vegetation coverage condition and seismic activity. Combining the field investigation with remote sensing interpretation, the amount of the loose deposits can be calculated, and debris flow initiation can be preliminarily analysed. Subsequently, the debris flow development trend in Jiuzhui gully watershed can be determined from different perspectives. Finally, on the basis of the obtained data, a comprehensive analysis can be conducted, and the conclusion can be drawn that the source materials, rainfall conditions and energy conditions can easily initiate debris flow. So, without engineering countermeasures or an early warning system, the debris flow in Jiuzhui gully may pose a great risk to the construction process and future operation of the hydropower station. In addition, the frequency and scale of the debris flow will be greatly magnified under the coupled effect of a strong earthquake and heavy rainfall.