Satellite solutions

Dr Einar Bjorgo

Getting precise information during a conflict or emergency means relief organizations can take quick and effective decisions. UNOSAT analyses satellite data to give disaster managers the details they need.

A major disaster has just occurred, affecting a vulnerable region of a developing country. The international humanitarian relief community is mobilizing, while local and national emergency response teams are trying to assess the situation. Floods and landslides have blocked roads to the area and communication lines are down. Rural villages surrounding the site are cut off. The first relief workers to reach the outskirts of the affected area report that a large number of people are dead and that crops, livestock and infrastructure are all badly damaged. No single person or agency has a comprehensive overview of the site. Donor nations understand the situation is serious, but don’t have enough information to take informed decisions on the type and amount of aid needed.

This is a typical scenario that emergency relief organizations have to face in almost every disaster. However, rapid response teams and disaster managers are increasingly using information from satellite technology to improve the level of assistance they give. Since 2002, our team at UNOSAT, the Operational Satellite Applications programme of UNITAR (United Nations Institute for Training and Research) has been analyzing satellite data to provide United Nations agencies, NGOs and UN member states with specific details suited to each emergency situation. We produce maps, provide damage reports with the locations of destroyed buildings or landslides and deliver statistical data on, for example, flooded areas per district.


At the onset of a conflict or disaster, one of the relief agencies will call the UNOSAT’s 24 hour phone number for assistance. Our on-call officer then contacts the data providers to programme the relevant satellites and gather images over the affected areas. About 70% of the data comes from public or commercial sources, while the rest is provided by the International Charter Space and Major Disasters (Space Charter), a service set up by the European and French space agencies. The next step is to search the archives for older imagery from the same area which can be used to compare with the new images.

By analyzing the satellite imagery, geo-spatial information and GIS (geographic information system) data using specialized software (see box) we can provide precise locations of destroyed infrastructure, such as buildings, bridges and roads and estimate the extent damage done by landslides, floods and storm surges. Combining landslide information with a map of the road network shows which roads are inaccessible, and which roads are open for the quickest delivery of aid. Combining population distribution data with flood information tells decision makers how many people are likely to be affected by the floods, and where. Areas most in need can be prioritized quickly and recovery teams directed to the exact location.

After analysis we make the maps and data available online for public distribution. Organizations working in the affected area can also add to this data with local details to build a more accurate picture of the locations.

Satellite analysis software

ERDAS Imagine
Can help identify changes in sensitive environments, such as urban growth or assess damage from natural disasters. Its image archive allows enables you to reference and measure the amount of change that has taken place in a geographic area.

ER Mapper
Software to display satellite imagery, integrate it with other data and produce a map or data file that can be printed or shared.

Geographic information system (GIS) for viewing and creating maps, analyzing distances and adding and editing data from satellite imagery.

We use a wide range of satellite sensors depending on the type and extent of the disaster. For example, it might be best to use radar images to gather information on the extent of flooding in an area, while earthquake damage assessment needs very high resolution optical data. The latest satellite imagery provides a level of detail down to 50 cm, meaning that even the number of people in a scene can be counted (see photo). For dynamic and often complex refugee situation, this information can be a good complement to field observations. Imagery is also useful to document potential human rights abuses on, for example, the right to adequate housing.

Examples of major disasters where satellite imagery has been used as an integral information management tool includes the Pakistan earthquake in 2005, Middle East crisis in 2006, Mozambique floods in 2008 and Cyclone Nargis over Myanmar, also in 2008. In 2007 alone UNOSAT supported a total of 46 emergencies most of which were floods, earthquakes and storms. Not all of them made the news but somewhere a satellite was watching.

Dr Einar Bjorgo is Head of Rapid Mapping, Applications and User Relations at UNOSAT, and Francesco Pisano is head of Institutional Affairs at UNOSAT, the Operational Satellite Applications programme of the UN Institute for Training and Research (UNITAR).

04 June 2008

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