邛海北岸官坝河山洪泥石流灾害特征及发展趋势

Disaster Characteristics and Development Trend of Guanba River Debris Flow in the North Shore of Qionghai Lake,Sichuan

官坝河为邛海流域最大支沟,近年来山洪泥石流频发,对邛海产生严重泥沙淤积灾害。本文在对官坝河1998年7月6日百年一遇泥石流灾害调查基础上,分析泥石流形成运动特征及其对邛海的淤积效应,揭示山洪泥石流暴发主要影响要素及发展趋势。研究表明:官坝河流域内物源丰富且形式多样,山洪泥石流暴发频率高且规模大;流域沟道长且比降大,沿途流速流量变化大且流态变换复杂;山洪泥石流对邛海泥沙淤积严重,大量泥沙不仅堆积在入湖口,还以浊流形式输移至湖心处;区域频繁地震活动、强降雨作用和不合理人类活动共同促进山洪泥石流暴发,预测山洪泥石流活动强度总体呈上升趋势。该成果可为官坝河流域规划管理和工程治理提供参考依据,有助于揭示区域山洪泥石流特征及其对邛海的泥沙淤积演化过程。

Guanba River is the largest debris flow gully around Qionghai Lake basin,and recently floods and debris flows occurred frequently which caused severe sediment deposition disaster in Qionghai Lake. Based on survey of hundred year debris flow occurred in July 6,1998,the debris flow movement process was analyzed in the Guanba River. The effect of debris flow on sediment deposition of Qionghai Lake was discussed,and the main influencing factors and development trend of debris flows were revealed. The results showed that different kinds of source materials are supplied in abundant,and the occurrence frequency of debris flows were often high with great scale. Due to longer gully and larger gradient along the channel,debris flow velocity and discharge usually changed greatly,and the transformation process of flow regime was complicated. The influence of floods and debris flows on sediment deposition of Qionghai Lake was very serious,and a large number of sediments was not only accumulated on the river estuary,but also transported into central lake. The coupling of frequent earthquakes,heavy rainfall and unreasonable human activities triggered debris flows,and it was forecasted that the probability of debris flow initiation will significantly increase in Guanba River. The results can provide reference foundation for river planning management and engineering treatment,and contribute to alleviate sediment deposition disasters of Qionghai Lake.