Anticipating the ice avalanche with radar data
Case Study
Author:洛伦兹·迈耶（Lorenz Meier）
The risk of natural hazards and the associated damage are globally on the rise. Extensive protection structures are costly and may not prevent damage by themselves. Spatial planning and preventative measures have become the most important actions for successful civil and assets protection. Permanent monitoring of the specific hazard processes allows for early detection of an imminent risk or the continuous modification of the hazard situation. The potential damage caused by an event can be remarkably reduced with warning and alarm systems – if set up and used correctly.
The Swiss-based technology company Geopraevent is an expert in this field. Geopraevent develops, installs and operates customised alarm and monitoring systems for various natural hazards, such as avalanches (snow and ice), rock fall, debris flows or floods. The applied technologies include different types of radar, e.g. the interferometric radar supplied by Italy-based leading provider of Ground Penetrating Radar and interferometric technology solutions IDS GeoRadar. Geopraevent currently runs more than 60 systems globally, many of them in high mountain environments. Recently, one of them clearly demonstrated the ability to预测迫在眉睫的电动汽车ent and react early: the failure of the Trift Glacier on Weissmies situated above the village of Saas Grund in Switzerland’s region of Wallis。
Challenging monitoring task in an alpine environment
The well-known summits of Fletschhorn (3993 metres), Lagginhorn (4010 m) and Weissmies (4017 m) separate the Saas-Valley from the Simplon Valley in southern Switzerland. Easily accessible from the cable car station located at Hohsaas, in Canton of Wallis, the Weissmies is one of the most frequently climbed peaks in the area.
2014年夏季，位于魏斯米斯西北部的Trift冰川显示出冰雪崩活动的增加。悬挂的冰川以前从下面得到冰的支撑，由于陡峭地区占主导地位的冰川质量损失而失去了稳定。瓦利斯当局的广州接近Geopraevent，要求监视冰川运动，以便在可能发生的冰倒入导致大冰/雪地雪崩的情况下实现早期行动。Geopraevent的专业工程师立即访问了测量地点，并向当地决策者和负责部门提供了glacier velocity data在安装当天晚上。
Interferometric radar data integrated into geotechnical analysis provides the detailed information required to the experts judging the situation. Interferometric radar is a reliable technique for short or long-term monitoring of multiple scales of displacements regardless of visibility and weather conditions. The radar measures spatially resolved deformation rates with high accuracy.IDS GEORADAR IBIS FM雷达is the system deliveringreliable and accurate data of displacements in real time despite the atmospheric correction needed in high altitudes。In addition, a high-definition camera was installed at this location and proved to be an excellent alternative for automatic long-term deformation analysis if weather is not an issue.
关键的滑坡和冰雪崩监测
尽管冰川上的湍流气氛有时会妨碍测量值，但每天都可以获得可靠的测量。为了说明高度可变的高山条件，Geopraevent添加了一个额外的处理步骤，该步骤在通过其通过其提供给客户之前验证数据的合理性online data portal。这为VAW/ETH教授的Martin Funk Group和当地的Geoformer GmbH的工程师提供了足够的数据interpret the prevailing hazard对于悬挂冰川下方的区域。
”经过近三年的连续雷达模拟toring, statistics showed that the radar delivered viable deformation data on 95 per cent of days. Radar measurements only failed temporarily during heavy snow storm due to surface changes caused by snow and rain,”said Richard Steinacher, physicist and project leader at Geopraevent.
Compared to the rest of the glacier moving at about 10 centimetres per day, the unstable part initially moved at a significantly higher velocity of approximately 25 cm per day. Between 2014 and 2017, dozens of small and harmless ice avalanches could be predicted from the radar data usually a few days in advance.
通过预测不可避免的来挽救生命
经过2。5年的成功操作后，2017年初的高分辨率摄像头取代了干涉范围，以进行视觉变形分析。该摄像机提供了出色的结果，该摄像机在允许的情况下跟踪了冰川每天的运动。摄像机分析揭示了从8月20日左右开始的冰川的明显加速th。In the beginning of September, it was clear that the glacier would fail soon.
To provide velocity data also during night and bad weather, Geopraevent re-installed the interferometric radar on September 7th。Velocities were on the order of 80 cm per day and accelerated to more than 2 m per day on Saturday, September 9th。那天的崩溃预测表明，冰量高达4000万m3would fail in the early morning of Sunday, September 10th。因此，有220名endangered village part of Saas Grund were evacuated。大多数不稳定ice volume collapsed, as predicted，在周日上午6点左右。幸运的是，冰的雷达干涉图揭示了十分钟之内的几小部分。没有造成损害，到上午8点。所有居民都可以返回家园。
Real time safety monitoring and long-term planning
IDS GEORADAR IBIS-FM系统从空间或时间的角度收集有关斜率行为的定量信息。它为实时即将发生的失败提供可靠的早期检测警报，并在长时间内进行准确的地理参考输出，使用户能够将雷达数据整合到斜坡故障机制的岩土技术分析中。
“The IBIS-FM radar accurately monitors multiple scales of displacements in real time, from early detection of slow movements to fast accelerations associated with slope collapse. The great operative range, up to 4500 metres allows to safely deploy the system in comfortably accessible areas without exposing people and equipment to hazardous zones,”said Paolo Papeschi, IDS GeoRadar GEO business unit manager.“Thanks to the most advanced automatic algorithms in the market, IBIS-FM delivers reliable and accurate data in all weather conditions. Monitoring experts can respond to slope hazards faster ensuring the safety of operators and the public.”
Geopraevent also installed an IDS GeoRadar system above Bondo in the region of Bergell, in Canton of Graubunden, Switzerland, after a massive landslide occurred in August 2017. The radar, installed on 3 September 2017, monitors the Pizzo Cengalo permanently anddetects millimeter-movements in all weather conditions。雷达允许尽早预测新的摇滚并采取适当的措施；预计2017年9月15日的岩石秋季活动大约提前一天。
