黄土高原淤地坝溃决型泥石流易发性评价

生态环境脆弱,极端气候频发,黄土高原淤地坝溃决形成的泥石流灾害事件增多,对当地人民生命财产安全带来巨大危害,有效的开展淤地坝溃决型泥石流灾害易发性评价对国土规划、防灾减灾具有重要意义。本文以黄土高原淤地坝溃决型泥石流为研究对象,从工程地质条件和降水量入手,基于产流模型、产沙模型,建立了淤地坝溃决型泥石流易发性评价模型及其计算方法,定义了库水位坝高比概念,并开展了考虑坝系结构的淤地坝溃决型泥石流易发性评价。研究结果表明,当降雨频率为5%、降雨时长4.5h以上时,大型淤地坝溃决形成泥石流易发性等级达到了高易发,一般降水情况下均为不易发和低易发;当降雨频率为20%、降雨时长4.5h以上时,中型淤地坝溃决形成泥石流易发性等级达到了高易发,一般降水情况下均为不易发和低易发;而当降雨时长1h以上时,小型淤地坝溃决形成泥石流易发性等级均达到高易发以上。此外,坝系的结构对淤地坝溃决型泥石流易发性也有一定的影响。

Evaluation on the susceptibility of debris flows induced by check-dam outburst in Loess Plateau

With fragile ecological environment and frequent extreme climate, the occurrence of debris flows induced by check-dam outburst in the Loess Plateau has increased, which will bring great harm to the safety of local people"s lives and property. Effectively carrying out the assessment of the susceptibility of debris flow disasters is of great significance for territorial planning, disaster prevention and mitigation. Therefore, the susceptibility evaluation model and calculation method of the debris flow induced by check-dam outburst were established, based on the sediment-yield model and the runoff-yield model. And, the ratio of the reservoir water level difference to the dam height was defined, and the susceptibility evaluation of debris flows induced by check-dam outburst considering the structure of the dam system was carried out. The results of the study show that the conditions for the susceptibility of large check-dams to reach a high level of susceptibility to debris flow are 5% rainfall frequency and more than 4.5h rainfall duration, while conditions for medium check-dams are 20% rainfall frequency and more than 4.5h rainfall duration. Under general rainfall conditions, the susceptibility of large and medium check-dam failures to form debris flows are both low and low susceptibility. When the rainfall lasts for more than 1 hour, the susceptibility level of debris flow induced by check-dam outburst will reach above high susceptibility. In addition, the structure of the dam system also has a certain impact on the susceptibility of debris flow induced by check-dam outburst.