Collaborative: Outburst From an Ice-Dammed Lake

合作：冰堰湖的爆发

• 批准号: 9912306
• 负责人: Joseph Walder
• 金额: $ 2.5万
• 依托单位: Geological Survey-Cascades Volcano Observatory
• 依托单位国家: 美国
• 项目类别: Interagency Agreement
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-06-01 至 2002-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9912306&HistoricalAwards=false
• 关键词: Collaborative; Outburst; Ice; Dammed; Lake

AbstractAnderson OPP-99-12129Fountain OPP-99-12180Walder OPP-99 -12306This is a collaborative study which includes Portland State University, the U.S. Geological Survey, and University of California, Santa Cruz. Outburst floods, or jokulhlaups, occur when ice-dammed water bodies drain suddenly. These floods can have devastating downstream effects. They can dramatically reshape stream channels and can be a hazard to human settlements. The mechanisms (timing, size, and geomorphic effect of outburst floods) by which impounded water is stored and released have been poorly studied because outburst floods are unpredictable. What is known comes primarily from observations in Iceland where subglacial and ice marginal lakes drain periodically. Elsewhere, observations have been serendipitous or after the fact. The Principal Investigators will investigate a site with predictable, annual outbursts on the Kennicott Glacier in Wrangell-St. Elias National Park, Alaska. The drainage of ice-marginal Hidden Creek Lake endangers nearby residents and visitors to the National Park.The Principal Investigators will examine outburst flood triggering to begin testing and refining existing theoretical models. Their hypothesis is that the ice dam does not form a "tight" hydraulic seal that is abruptly broken by flotation. Instead, as the lake level rises, it initially becomes connected to a distributed basal drainage system resulting in a slow, stable leak. The lake level eventually rises enough that hydraulic connection is established with an arborescent channel network away from the edge of the glacier. The lake then drains rapidly, and may be related to seasonal development of a conduit system or to the termination state of a glacier surge.The proposal has four main goals to the field work: 1) to measure ice-dam deformation as the lake fills and empties and characterize how the ice dam behaves mechanically; 2) to measure lake level as a function of time, determine lake hypsometry, and measure the lake's thermal structure. 3) to examine the hydraulic integrity of the ice dam and temporal changes in the subglacial drainage system using boreholes; and 4) to monitor the flood and changes in channel morphology in the outlet river near the glacier terminus.

摘要Anderson OPP-99-12129Fountain OPP-99-12180Walder OPP-99 -12306这是一项合作研究，包括波特兰州立大学、美国地质调查局和加州大学圣克鲁斯分校。 当冰坝水体突然排水时，就会发生爆发性洪水（jokulhlaups）。这些洪水可能会对下游造成毁灭性的影响。 它们可以极大地重塑河道，并对人类住区造成危害。 由于溃决洪水是不可预测的，因此对蓄水和释放水的机制（溃决洪水的时间、规模和地貌效应）的研究很少。 已知的信息主要来自冰岛的观测，那里的冰下湖和冰缘湖会定期排水。 在其他地方，观察是偶然的或事后的。 首席研究员将调查兰格尔-圣路易斯肯尼科特冰川上每年可预测爆发的地点。阿拉斯加埃利亚斯国家公园。 冰缘隐溪湖的排水危及附近居民和国家公园的游客。主要研究人员将研究突发洪水的触发因素，以开始测试和完善现有的理论模型。 他们的假设是，冰坝不会形成因漂浮而突然破裂的“紧密”液压密封。 相反，随着湖水位上升，它最初与分布式基础排水系统相连，导致缓慢、稳定的泄漏。 湖水位最终上升到足以与远离冰川边缘的树状渠道网络建立水力连接的程度。 随后，湖泊迅速排水，可能与管道系统的季节性发展或冰川涌动的终止状态有关。该提案的实地工作有四个主要目标：1）测量湖泊充水时冰坝的变形清空并表征冰坝的机械行为； 2) 测量湖泊水位随时间的变化，确定湖泊测高，并测量湖泊的热结构。 3）利用钻孔检查冰坝的水力完整性和冰下排水系统的时间变化； 4）监测冰川终点附近出口河的洪水和河道形态变化。