PILOT STUDIES WITH A PHOTOGRAMMETRIC GLACIER LAKE OUTBURST FLOOD EARLY WARNING SYSTEM
PILOT STUDIES WITH A PHOTOGRAMMETRIC GLACIER LAKE OUTBURST FLOOD EARLY WARNING SYSTEM
复制标题
摄影测量冰川湖溃决洪水预警系统试点研究
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
G. Casassa
中科院分区：
文献类型：
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作者：
H. Maas;C. Mulsow;A. Wendt;G. Casassa
抽象的。冰川湖溃决洪水 (GLOF) 描述了世界许多地区的环境风险，其潜在损害日益增加。 GLOF 通常是由冰川边缘湖泊引起的，这些湖泊突然在冰川底部找到了排水路径，而冰川由于当地或全球气候变化而不稳定并消退。在典型的GLOF事件中，冰川边缘湖泊可能会在24小时内完全排干，从而在冰川下游地区引发大洪水。该论文记录了巴塔哥尼亚北部冰原（智利）最近发生的一些 GLOF 事件，并提出了陆地摄影测量冰川边缘湖监测系统。该系统基于定期拍摄图像的相机。在这些图像中，可以通过跟踪预定义图像点处的水陆界面来检测水位的变化。由于排水机制的特点是冰川底部逐渐侵蚀和融化，GLOF 通过湖中水位的逐渐下降来表示。可以通过图像序列处理方法以亚像素精度检测水位变化。如果存在湖底地形（或至少一个穿过湖的高度剖面）的 3D 模型，单视场图像序列中的水位变化可能会转化为体积损失。这里的基本思想是地形轮廓与图像中检测到的水位的交集并投影到对象空间中。相机方向是通过 GPS 支持的摄影测量网络确定的。例如，可能由风引起的相机方向变化可以通过跟踪图像中的一些基准标记来补偿。该系统已用于巴塔哥尼亚北部冰原两个冰川边缘湖泊的试点研究。这些湖泊的深度约为80-100米。较大的一条长5公里，最大体积约2亿立方米。在试点研究期间，可以记录和处理多个 GLOF 事件。可以以分米级精度确定水位变化。结果证明了该概念的可行性，这必须由数据遥测和报警系统来完成。
Abstract. Glacier Lake Outburst Floods (GLOFs) depict an environmental risk with an increasing damage potential in many regions of the world. GLOFs are often caused by glacier margin lakes, which suddenly find a drainage path underneath the bottom of a glacier, which is destabilized and retreating as a consequence of local or global climate changes. In a typical GLOF event, a glacier margin lake may drain completely in 24 hours, causing a large flood wave in the area downstream the glacier. The paper documents some recent GLOF events in the Northern Patagonian Icefield (Chile) and presents a terrestrial photogrammetric glacier margin lake monitoring system. The system is based on a camera taking images at regular time intervals. In these images, variations of the water level can be detected by tracking the water-land interface at pre-defined image spots. Due to the drainage mechanism, which is characterized by progressive erosion and melting at the bottom of the glacier, GLOFs are indicated by a progressive water level drop in the lake. Water level changes may be detected with subpixel accuracy by image sequence processing methods. If a 3D model of the lake bottom topography (or at least one height profile through the lake) exists, water level changes in monoscopic image sequences may be transformed into volume loss. The basic idea herein is the intersection of a terrain profile with a water level detected in the image and projected into object space. The camera orientation is determined through a GPS-supported photogrammetric network. Camera orientation changes, which may for instance be induced by wind, can be compensated by tracking some fiducial marks in the image. The system has been used in a pilot study at two glacier margin lakes in the Northern Patagonian Icefield. These lakes have a depth of about 80 - 100 meters. The larger one has a length of 5 km and a maximum volume of about 200,000,000 cubic meters. During the pilot study, several GLOF events could be recorded and processed. Water level changes can be determined at decimeter level precision. The results prove the feasibility of the concept, which has to be completed by a data telemetry and alarm system.