Guest article from SuperGeo.
On September 21st, 1999, a 7.3 strong magnitude earthquake rocked Taiwan. It caused thousands of death and injuries, which was the most severe earthquake ever by the end of the 20th century in Taiwan. After that, the strong aftershocks hit all around Taiwan continuously, increasing the number of death and injured constantly. Taichung City in particular was threatened the most.
Located in the circum-pacific seismic belt, the earthquakes occur very often in Taiwan and often cause great loss of life and property damage. For the reason that the earthquake cannot be predicted and always causes serious damage, the local governments devote to promoting and enhancing the urban disaster prevention capability through the establishment of urban disaster prevention system. It makes possible to reduce the death and injured caused by the unpredictable disaster and provide the highly efficient disaster relief mechanism and disaster recovery.
The scope of the project covers the entire Taichung city. Taichung city, a 163.4-square kilometers area and having a population of around 950,000, is one of the focus development cities in the western Taiwan. Taichung is a dense city composed of residential and commercial districts. Since the zones were developed in different periods and the buildings were built in different years, difficulties in making disaster prevention plans confronted the local government. Even though some of the buildings have been re-built in recent years, these challenges still exist.
The goal of the project is to review the structure of urban space, formulate the spatial contents and levels of the urban disaster prevention, plan the spatial strategies for refuge and rescue, and further implement the basic constructions of disaster prevention facilities in Taichung city. The disaster prevention evacuation circulation and the entire emergency response system can be set up. Therefore, it makes possible to equip the circulation with the capabilities of self-supply and support so that Taichung city turns to be a safe city.
The project applies SuperGIS Desktop to create the complete spatial data related to the disaster rescue in Taichung city. Besides, with SuperGIS Spatial Analyst and SuperGIS Network Analyst of SuperGIS Desktop, the related staff can further analyze the created spatial data and build up the spatial attributes of the disaster prevention passages and refuge sites, such as distance, potential level, area, etc. And all of the data can be considered as the foundation for creating the Urban Disaster Prevention Spatial System.
The Taichung City Urban Disaster Prevention Spatial System, targeting the urban physical public space, is created up according to the time series of when disasters occur in individual space and the basic needs for rescue activities. Besides, it also refers to the researches and relevant papers about earthquakes as well as the experiences in planning disaster prevention and feedbacks from Taipei city and Hualien county.
Urban Disaster Prevention Spatial System is divided into two major systems: Disaster prevention network and Evacuation circulation.
When the disaster occurs, the disaster prevention network which is aimed to help people rapidly reach the refuge sites and enable the rescue staff to arrive the spot of disasters as soon as possible is the first system that operates. Therefore, the operation of the disaster prevention network will influence the ensuing evacuation and rescue. The well design of the disaster prevention network plays a crucial role in Urban Disaster Prevention Spatial System.
The disaster prevention network of Urban Disaster Prevention Spatial System is designed mainly according to the locations of existing roads and the physical spatial conditions. It is aimed to help people and rescue unit reach the destination rapidly when disaster occurs. It has four levels:
(1) Emergency passage: The main subjects are the roads wider than 20 meters.
(2) Rescue and conveyance passage: The main subjects are the roads wider than 15 meters.
(3) Fire passage: The main subjects are the roads wider than 8 meters.
(4) Evacuation passage: The main subjects are the roads narrow than 8 meters.
Evacuation circulation is the area defined by the geographic and physical spatial conditions and the mode and extent of evacuation. When the severe disaster occurs, the people within the evacuation circulation can rapidly enter the temporary refuge sites in the evacuation circulation to wait the rescue staff or stay until the aftershocks stop. After that, the rescue staff could lead the people to the specified safe refuge sites. The evacuation circulation is not only the least unit to support one another in disaster prevention but also could be regarded as the reference for the administration of the rescue work, which aids the correlative organizations in controlling the rescue mode.
The aim of Evacuation Circulation is to rescue and security. According to the terrain environment, development status of each zone, the existing resource distribution for disaster prevention and co-working with the disaster prevention network, 52 evacuation circulations are divided. Within the 52 evacuation circulations, there are 119 temporary evacuation sites, 86 temporary refuges and 2 long-term refuges (including 26 substitute sites) set up for people to temporarily rest and stay. In addition, to collaborate with the constitution of evacuation circulations, the service sites include medical treatment (13 sites), fire fighting (13 sites), and police (25 sites) so that the rescue units can rapidly start the rescue.
The establishment of Urban Disaster Prevention Spatial System helps people to evacuate more rapidly and to understand the escape direction to reduce the loss of life and property of the public when the disaster occurs. In addition, if the system could collaborate with the systems of other counties or cities, it can not only improve the disaster-prevention efficiency but also benefit the urban security of cities.