预见冰雪崩的雷达数据

作者：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预测即将发生的事件并提早反应：Trift冰川在位于瑞士瓦利斯地区SaaS Grund村庄上方的Weissmies上的失败。

在高山环境中挑战监控任务

Fletschhorn（3993米），Lagginhorn（4010 M）和Weissmies（4017 m）的著名峰会将SaaS-Valley与瑞士南部的Simplon Valley分开。从位于瓦利斯广州霍萨斯的缆车站很容易到达，魏斯米斯是该地区最常见的攀登峰之一。

In summer 2014, the Trift Glacier, located on the north-west face of Weissmies, showed increased ice avalanche activity. The hanging glacier, formerly supported by ice from below, had destabilised due to glacier mass loss predominating in steeper areas. Canton of Wallis authorities approached Geopraevent with the request to monitor the glacier movement to enable early actions in case of possible ice failures resulting in a large ice/snow avalanche. The specialised engineers of Geopraevent visited the measurement site immediately and supplied the local decision makers and responsible authorities withglacier velocity dataon the evening of the day of installation.

整合到岩土分析中的干涉雷达数据提供了判断情况所需的详细信息。干涉测量雷达是一种可靠的技术，用于短期或长期监测多个位移的尺度，无论可见性和天气条件如何。雷达以高精度测量空间分辨的变形速率。IDS GeoRadar IBIS FM radar是交付的系统尽管高度需要进行大气校正，但实时的可靠和准确的位移数据。此外，在此位置安装了高清摄像头，如果天气不是问题，则被证明是自动长期变形分析的绝佳选择。

Critical landslide and ice avalanche monitoring for safety

Despite the turbulent atmosphere over the glacier that can hamper the measurements at times, reliable measurements have so far been obtained daily. To account for the highly variable alpine conditions, Geopraevent added an extra processing step that verified the plausibility of the data before making it available to the customer via itsonline data portal。This provided sufficient data for VAW/ETH Professor’s Martin Funk group and the local geoformer GmbH’s engineers to解释现行危险for the area below the hanging glacier.

“After almost three years of continuous radar monitoring, 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.

与其余的冰川以每天约10厘米的速度移动相比，不稳定的部分最初以每天约25 cm的速度明显更高的速度移动。在2014年至2017年之间，通常会提前几天从雷达数据中预测数十个小而无害的冰雪崩。

Saving lives by forecasting the inevitable

After 2.5 years of successful operation, the interferometric radar was replaced by a high-resolution camera in early 2017 for visual deformation analysis. This camera delivered excellent results that tracked the movements of the glacier daily if visibility conditions permitted. The camera analysis revealed a distinct acceleration of the glacier starting around August 20^Th。在9月初，很明显，冰川很快就会失败。

为了在夜晚和恶劣天气中提供速度数据，Geopraevent于9月7日重新安装了干涉范围^Th。Velocities were on the order of 80 cm per day and accelerated to more than 2 m per day on Saturday, September 9^Th。Breakoff-predictions on that day suggested that an ice volume of up to 400’000 m³将在9月10日星期日清晨失败^Th。Consequently, 220 inhabitants of theendangered village part of Saas Grund were evacuated。Most of the unstable如预测的那样，冰量崩溃了, around Sunday, 6 a.m.. Fortunately, the ice detached in several small portions within ten minutes as revealed by the radar interferograms. No damage occurred and by 8 a.m. all inhabitants could return to their homes.

实时安全监测和长期规划

IDS GeoRadar IBIS-FM system collects quantitative information on slope behaviour from either a spatial or a temporal point of view. It provides reliable early-detection alerts on impending failures in real time, as well as accurate geo-referenced outputs over long periods of time allowing users tointegrate radar data into geotechnical analysis of slope failure mechanisms。

“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,”IDS Georadar Geo业务部门经理Paolo Papeschi说。“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在2017年8月发生了巨大的山地滑坡之后，在瑞士Graubunden的伯格尔地区安装了IDS Georadar系统。在所有天气条件下检测毫米运动。The radar allows to predict new rockfalls early and initiate appropriate measures; a rock fall event on 15 September 2017 was predicted about one day in advance.