The role of remote sensing and GIS in risk mapping and damage assessment for disasters in urban areas

The increased vulnerability of many urban areas, especially in developing countries is a major reason of concern. Emphasis should be given to the reduction of vulnerability in urban areas. Most of the data required for disaster management has a spatial component, and is also changing over time. Therefore the use of Remote Sensing and Geographic Information Systems has become essential in urban disaster management. This paper briefly presents three case studies of urban disaster management, dealing with the prevention as well as the disaster relief and rehabilitation phases, for different types of disasters. The first case study deals with the assessment of the area affected by the fireworks explosion in the city of Enschede, the Netherlands, on 13 May 2000. Old and new vertical and oblique airphotos were used, combined with maps and spatial database data. The second example deals with the damage assessment of the earthquake of 25 January 1999 that hit the departments of Risaralda and Valle de Cauca in Colombia. The inventory of the damage consisted of an appraisal of the damage to houses and other structures. For this purpose aerial photographs were made of the damaged areas and experts assessed the damage and the type of structure visually on the ground. The damage inventory was digitised, and the aerial photographs were used, in combination with a Digital Elevation Model, to generate a series of orthophotos. The third case study deals with a multi-hazard and risk evaluation for the city of Turrialba, Costa Rica. Floods, landslides and earthquakes regularly affect the area. The city is also located close to an active volcano. In order to assist the local government in the development planning and emergency management, a database was constructed at parcel level, containing cadastral information as well as hazard and vulnerability information. Large-scale orthophotos were used to digitise the Van Westen und Hofstee 443 parcels in the city, and data was collected by means of interviews and sidewalk surveys. The resulting database can be used to analyse risk scenarios, and calculate potential damage.