冰碛湖溃决灾害评估及应急泄流技术

Assessment of moraine-dammed lake outburst and emergency discharge technologies

冰碛湖是我国西南高海拔山区、高山峡谷地带常见的一种湖泊。在全球气候变暖、热带高海拔地区变暖趋势更为明显的背景下,冰碛湖溃决的风险加大。在回顾冰碛湖溃决诱因的基础上,阐述了冰碛湖溃决风险评价的指标和评估方法以及冰碛湖溃决洪水(泥石流)的初步模拟方法,总结出应急泄流是冰碛湖最可行的排险方法,分析了开渠形成冲切泄流和保证坝体稳定泄流的适用条件,详细阐述了冲切泄流中的关键问题,包括过流标准、过流流速的确定和泄流渠的布置以及施工方法的选取。同时,简要回顾了西藏皮达湖、龙巴萨巴湖的排险,阐明了冰碛湖应急泄流中可能遇到的难题和相应的解决方法。

Moraine-dammed lake is commonly existed in the southwest part of China, where has high-altitude mountains and canyons. Under the influence of global warming and increasingly warming tendency in tropical high-altitude areas, the risk of moraine-dammed lake outburst increases. Based on causes analysis of moraine- dammed lake outburst and risk assessment indicators and methods, simulation methods of floods/debris are put forward. It is concluded that emergency discharge is the best feasible measure of eliminating risk of moraine- lake. The applicable condition of opening discharge channel and consolidating the dam for water discharge are analyzed. Key issues related to opening discharge channel are examined, including determination of discharge standard and flow velocity, layout of discharge channel as wefl as selection of construction method. A brief in- troduction is made on the hazard mitigation of Pida Lake and Longbasaba Lake in Tibet in order to illustrate the challenges faced by emergency discharge and give possible solutions.