3d-gis for Barrier Lake Disaster Reduction and Risk Management

On May 12, 2008 a large earthquake occurred in Wenchuan, resulting in significant casualties and enormous property loss, and shocked the world. Then the Tangjiashan barrier lake caused by earthquake, made a serious threat to 1.3 million people living downstream. From its formation to being successfully disposed, the entire emergency management of Tangjiashan barrier lake lasted about a month. In this process, GIS has played an enormous role, for example, fast access precise coordinates of disaster areas by 3D-GIS. However, looking back to the entire process of emergency management, we can envision that GIS could do a better job. In this paper, we propose a comprehensive framework to integrate various GIS technologies in emergency management. a* Corresponding author. Key Laboratory of Geo-Informatics of State Bureau of Surveying and Mapping Chinese Academy of Surveying and Mapping, Beijing, China. Email: [email protected]. 1. NTRODUCTION A barrier lake (or landslide dam, debris dam, quake lake) is a lake or a dam reservoir formed by landslides, debris flows or volcanic lave flows impounding the river and storing water to a certain degree. It is usually caused by earthquake, windstorm, and volcanic eruption in nature (though there are human factors sometimes). Engendered by unstable geological conditions, barrier lakes often have no controlled spillway, so it frequently fails catastrophically and leads to downstream flooding, causing high casualties. The earthquake occurred in Wenchuan, China, on May 12, 2008, resulted in over 50 thousand of landslides, collapses, as well as 35 barrier lakes in tributaries of some important rivers [Liu 2008]. The Tangjiashan barrier lake was one of them, simultaneously became the most threatening one owing to its large scale and geographic position. According to statistical data, 50 percent of the barrier lakes tend to break in ten days, and more than 90 percent break in a year [Nie et al. 2004]. Hence, the government should adopt efficient measures to solve the barrier lake problem as soon as possible to ensure the safety of people’s lives and properties. Scientific methods and technologies are urgent needed to provide auxiliary support to the decision making in barrier lake disaster reduction. 3D-GIS is such a technology that has huge advantages in visual expression of disaster-related information, especially the 3D visualization of the topography (or the surface features) of the study area as well as the distribution and the trend of the disaster information. Benefiting from this, 3D-GIS has played an important role in the process of eliminating danger of the Tangjiashan barrier lake. However, there are still many obstacles in the application of the current 3D-GIS products because of the copyright limitation, the high cost or the lack of consideration about the special factors in barrier lake problems. In this paper we take the Tangjiashan barrier lake as an example to analyze and summarize major issues in conventional barrier lake’s situation study and risk elimination. We attempt to explore the key technologies in construction of a management platform based on three-dimensional GIS to deal with the problems in barrier lake disaster reduction and risk management in order to develop the autonomous prototype system.