Geographical information and remote sensing systems play a special role in the Hindu Kush-Himalayan region in support of informed decision making. This series of information sheets presents information on basic technologies, approaches, and applications related to geographical information and remote sensing, and used or developed by ICIMOD, as a background for understanding for policy makers, development workers, and others.
In general it is more important after a disaster to have a rapid overview of the damage than to have a detailed assessment; information is needed within hours (or up to a few days for large areas). The best images for this are those with lower resolution from satellites that pass over the area many times within a short period (e.g., MODIS, NOAA, and GOES). Satellite images with moderate to high resolution can be used subsequently for more precise damage estimation for resource allocation (e.g., Landsat, ALOS, ASTER, IKONOS, and QuickBird). During disasters, it can be difficult to obtain cloudfree images and microwave satellite data can play a significant role in detecting and monitoring events (e.g., ALOS Palsar, IRS RISAT, RADARSAT, ENVISAT ASAR).
Maps are generated from the remote sensing data through a series of steps: integration of the spatial data, data analysis, interpretation, layout, quality control, editing, and revision. The final maps showing the required information on the disaster are sent to the users. Layers can be added from existing maps and information showing, for example, the position of affected infrastructure like bridges, health facilities, schools, and housing, that may play a decisive role in approaches to disaster response, Some examples of rapid mapping are given below.
Close contact and interaction with key actors in the user community are as important as the actual data processing and delivery during the cycle from a request for assistance through to providing the map or other product. Crisis teams need to coordinate by linking earth-observation systems, information extraction, and uninterrupted dissemination to trained decision makers and/or field staff of relief organisations. When this is done, space-based crisis mapping can make a large contribution to disaster-relief operations.