Disaster Mitigation


Human and economic losses due to natural disasters continue to increase despite best efforts undertaken by communities, governments and international support organisations. Data for 2003 from reinsurance companies report the occurrence of around 700 ‘disasters’, with over 50,000 people killed, almost five times as many as in the previous year (11,000); such a high number of victims has only been recorded four times since 1980. Economic losses rose to over US$60 billion (in 2002: US$55 billion). Swiss Re, the world's second largest insurer, has estimated that the economic costs associated with hazards resulting from global warming alone could increase to US$150 billion each year in the coming decade.

Economic and human impacts of disasters 1973-2002

Developing countries are disproportionately affected, with their losses rising to about five times higher per unit of GDP than for the rich countries, sometimes exceeding years of hard-won and desperately needed economic development. Natural disasters should be recognized as a major obstacle to sustainable development.

The natural hazards which lead to these disasters with the potential to create loss to humans and to their welfare include: floods, typhoons, tsunamis, hurricanes and cyclones, earthquakes, tornadoes, volcanic eruptions, landslides, subsidence, drought, and wildfires – coupled with a wide range of pollution and other events that are at least partially human induced, and secondary disasters such as disease outbreaks that commonly follow floods or earthquakes.

A wide variation in the number and intensity of such natural hazards is normal and to be expected – but the events of the last few decades suggest that there may be an upward trend caused by human activities, including growing numbers living in areas affected by disasters. Many scientists believe that the recent upsurge of weather-related natural disasters is the product of increased global warming. There were three times as many great natural disasters in the 1990s as in the 1960s, while disaster costs increased more than nine-fold in the same period. The reason for the upward trend in loss of life and wealth is apparent; ninety per cent of disaster victims worldwide live in developing countries, where poverty and population pressures force growing numbers of poor people to live in harm's way – on flood plains, in earthquake-prone zones and on unstable hillsides.

Disaster mitigation information

Natural disasters cannot be prevented, but their social and economic impacts can be reduced through effective disaster management programmes. Disaster management involves a series of information-intensive activities:

  • disaster knowledge and prevention: including activities aimed at the avoidance or reduction of risks, through the evaluation of the characteristics of hazards, such as their probability of occurrence, severity and location, as well as the vulnerability of life and property to such hazards;
  • disaster preparedness and forecasting: activities that reflect the readiness of the public to cope with a specific hazard; actions taken in response to an ongoing or impending hazard; actions such as hazard forecasting, warning and prediction;
  • emergency response, recovery and reconstruction: activities undertaken immediately before and after the onset of a hazard to reduce the effects of a disaster after it occurs; assessment of the extent and severity of the damage; relief measures such as delivering food, health care and other sustenance; implementation of remedial and reconstruction measures.

Hazards are characterised by information on geology, tectonics, seismicity, regimes of rivers and their water basins, amount & characteristics of fuel, local meteorological conditions, terrain and topography. Vulnerability depends highly on the location of residential areas and urban centres and assets such as hospitals, schools, plants, road and utility networks, and the likely effect of a given disaster.

Meteorological forecasts are essential to prediction and warning of hurricanes, floods and fires. So far no reliable prediction system is available for earthquakes, although warnings may be issued for volcanoes and tsunamis. Evacuation plans and similar measures are triggered accordingly and their efficiency is conditioned heavily by available information on settlements, roads, etc.

Disaster reduction and risk management has moved rapidly up the policy agenda of affected governments and the international community. This trend has led to the adoption of the International Strategy for Disaster Reduction (ISDR) by governments to promote implementation of the recommendations emanating from the International Decade for Natural Disaster Reduction (IDNDR, 1990-1999). The World Conference on Disaster Reduction (WCDR), Kobe, Japan (January 2005) is a milestone event to increase the profile of disaster risk reduction in development planning and practice.

The role of Earth observation satellites

Tropical Storm Jeanne on 27th September, 2004

Increasingly, data derived from Earth observation satellites is being used to contribute to the information requirements of different phases of disaster mitigation programmes.

Weather satellites, have been used for more than 40 years to support forecasting of intensive weather hazards such as tropical cyclones, severe storms, and flash flooding. Today, many countries operate weather satellites, coordinating their activities to benefit an international user community through organisations such as WMO. Derived products are produced routinely several times per day, many of them focused on particular hazard events. Tracking sequences of tropical cyclone images from geostationary satellites as well as storm intensities and atmospheric winds derived from these images provide information for forecasting landfall – where and when. Recent integration of experimental products, such as ocean surface winds from scatterometer instruments and moisture or rainfall from microwave instruments, has improved these forecasts.

Forecasts and warnings for other severe storms utilise products also derived from sequences of images from geostationary satellites. Flash flood forecasts are improved with the integration of precipitation estimates derived from analysis of cloud imagery, and severe storm index sequences are utilised for warnings of severe storms such as tornadoes.

By allowing society time to prepare for or avoid an impending hazard, such forecasting and early warning systems incorporating satellite data have dramatically reduced deaths, injuries, property damage and other economic losses.

In recent years, Earth observation satellites have demonstrated their utility in providing data for a wide range of applications in disaster management. These include the mapping and monitoring of hydrological and seismic hazards, variables affecting climate and weather, land use, the extent of damage due to volcanic eruptions, oil spills, forest fires, the spread of desertification, and the forecasting of floods and droughts. Information from satellites is often combined with other relevant data in geographic information systems (GIS) in order to carry out risk assessment and help identify areas at risk.

Some of these capabilities are shown in the table below.

Although Earth observation satellites have demonstrated their considerable potential in supporting a range of disaster management activities, space agencies have recognized that further steps are necessary to persuade the disaster management community to assimilate these new technologies into their operations. Further, to meet the needs of such a diverse range of hazards and their often critical timescales for information, the space agencies decided to pool the satellite resources of different countries more effectively for the benefit of the international community.

International Charter on Space and Major Disasters: The aim of this charter, initiated by the French (CNES) and European (ESA) space agencies, is “to supply during periods of crisis, to States or communities whose population, activity or property are exposed to an imminent risk, or are already victims, of natural or technological disasters, data providing a basis for critical information for the anticipation and management of potential crises”. CSA (Canada), ISRO (India), and CONAE (Argentina) are also party to the charter. Since the Charter became operational on 1st November 2000, authorised civil defence organisations may enlist support from space by calling a telephone number, 24 hours a day, 365 days a year. Rescue and civil defence bodies of the country to which the participating agencies belong are registered authorised users. Civil protection authorities of other countries may also submit requests by contacting their sister organisations through existing cooperation mechanisms.

The Charter has proven to be a highly effective and practical mechanism for delivering applications of Earth observation satellite data to those in society in most dire need. The Charter has been activated over 55 times since its inception, and continues to support several events monthly in response to calls for assistance from countries all around the globe.

The International Disasters Charter has been activated more than 55 times since November 2000 to supply Earth observation satellite data to crisis-struck regions

UNOSAT: UNOSAT is a consortium of UN agencies, remote sensing service companies and space agencies, and is supported by a number of CEOS Members and their national governments. UNOSAT’s objectives are to facilitate the planning and monitoring processes of local authorities, local technicians, development project managers and humanitarian field operators working in coordination with or within the framework of UN activities, on issues such as disaster management, risk prevention, peace keeping operations, post-conflict reconstruction, environmental rehabilitation and social and economic development.

UNOSAT aims to encourage, facilitate, accelerate and expand the use of accurate geographic information derived from EO-satellite imagery by professionals involved in achieving vulnerability reduction, crisis management and recovery as well as sustainable development at the local level.

RESPOND: RESPOND is an alliance of European and international organisations working with the humanitarian community to improve access to maps, satellite imagery, and geographic information. RESPOND is a five-year staged programme providing: guaranteed access to global mapping; access to an archive of detailed base mapping, imagery and thematic mapping; and access to rapid assessment maps for major crisis. RESPOND is one of the services initiated under the GMES (Global Monitoring for Environment and Security) initiative of ESA and the European Commission. Since 2004, the RESPOND consortium has been collaboratively producing products for the Sudan Darfur Crisis.

The reports of the CEOS Disaster Management Support Group provide excellent references on the use of Earth observation for disaster management.

Satellite imagery of flood extent is increasingly used to target response operations: examples are shown for Sudan/Darfur, August 2004 and for the River Elbe, August 2002

Future challenges

There are a number of obstacles to the increased use of Earth observation satellite data in disaster mitigation applications – both institutional and technical.

Institutionally, it is recognized that there must be greater cooperation between satellite-operating agencies, between these agencies and the commercial sector, and between all data providers and the disaster management community. This cooperation is essential if we are to achieve the scale and speed of response which is required to face diverse and time-critical disasters. In order to promote wider acceptance and use of space systems by disaster management users, the space and services communities must create the appropriate tools and continue to promote a mutual understanding and dialogue between the disaster management and space sectors.

Technically, we can expect to see future efforts aiming at providing satellite-derived information more rapidly and at higher spatial resolutions, consistent with the needs of many disaster management applications. A number of new capabilities can also be expected, including:

  • improved spatial and temporal resolution of storm tracking from geostationary satellites, combined with new atmospheric wind measurements (from planned lidar instruments) and with ocean surface wind measurements (from scatterometers), to provide more accurate early warning services;
  • operational tectonic strain-mapping and surface deformation monitoring techniques in support of earthquake and volcano warning systems;
  • more precise precipitation measurements and modelling results as important inputs for flood warnings;
  • a trend towards broad compatibility of satellite-derived information with the GIS employed to aid disaster management programmes.

Interferometric SAR techniques may be used to monitor fault motions and strain. 9 Volcanic Ash Advisory centres world-wide use ash cloud data from satellites to ensure aviation safety.

Hazard Use of EO satellites
Hurricanes & tornadoes Weather satellites are used extensively for detection and tracking of storms and contribute effectively to the forecasting capability. Recent satellite missions providing more detailed and frequent measurements of sea surface wind speed and tropical rainfall mapping have significantly improved forecasts.
Volcanic eruptions & earthquakes In-situ systems and Global Positioning System (GPS) satellites provide valuable information on seismic and volcanic activity. EO satellites provide complementary data in support of disaster mitigation and response: interferometry techniques of radar sensors are used to monitor fault motions and strain, and signs of Earth surface deformation and topographic changes. Very high resolution sensors are used to map damage assessment, direct response efforts, and aid reconstruction planning.

Satellite data is the primary information source employed by the 9 Volcanic Ash Advisory Centres operational world-wide which issue volcanic ash cloud warnings, an essential information source for international aviation safety.

Wildfires A number of satellites now contribute routinely to each stage of wildfire hazard management world-wide, including: fire risk mapping using land cover and fire fuel assessments, moisture data, digital elevation maps, and meteorological information – all derived from satellite; fire detection and early warning; fire monitoring and mapping; burned area assessment.
Oil spills Synthetic Aperture Radar (SAR) data is used as the basis for ocean surveillance systems for oil slick detection, to provide enforcement and monitoring capabilities to deter pollution dumping. The SAR data is processed within 1-2 hours of the satellite overpass and used by pollution control authorities to cue aircraft surveillance. Surveillance systems are currently operational in Norway, and Denmark, and under trial in the Netherlands, Germany, and the UK.

SAR data and optical data are also used to develop information in support of major coastal oil spills, to assist in mapping pollution extent and managing the response.
Drought Currently, multichannel and multi-sensor data sources from geostationary satellites and polar orbiting satellites are used routionely for determining key monitoring parameters such as: precipitation intensity, amount, and coverage, atmospheric moisture and winds. Instruments with spectral bands capable of measuring vegetative biomass are also used operationally for drought monitoring. The Famine Early Warning System (FEWS) in Africa, for example, exploits operational use of satellite technology to reduce the incidence of famine in sub-Saharan Africa by monitoring the agricultural growing season. Monitoring is carried out through “greenness maps” derived every 10 days from the AVHRR instrument, and from rainfall estimates.
Floods Earth observation satellites are used for the development of flood impact prediction maps, contributing measurements of landscape topography, land use, and surface wetness for use in hydrological models. Weather satellites provide key information on rainfall predictions to assist flood event forecasting. Since optical observations are hampered by the presence of clouds, SAR missions (which can achieve regular observation of the earth’s surface, even in the presence of thick cloud cover) are frequently used to provide near real-time data acquisitions in support of flood extent mapping.

US firefighters and land managers are using NASA’s MODIS data to combat wildfires

A crippled tanker carrying around 67,000 tons of oil split in half off the northwest coast of Spain on Nov. 19 2002, threatening one of the worst environmental disasters in history.

Within the framework of the International Disasters Charter ESA provided satellite images almost daily since 17 November from its ERS and Envisat spacecraft in support of relief efforts.

STOP PRESS: December 2004 Tsumani

The recent tragedy striking the coastlines of the Indian Ocean has highlighted the benefits of international cooperation in Earth Observation for the management of disaster relief, while demonstrating the scope for improved cooperation in the future. Immediately after the first tsunami struck in the Eastern Indian Ocean the International Charter on Space and Major Disasters was invoked by three different agencies. India activated the Charter for access to data over its own territory, the UN Office of Outer Space Affairs activated in relation to Indonesia and Thailand while the French Civil Protection Agency opened the Charter for the case of Sri Lanka.

As a result, data have been acquired from many satellite sources since immediately after the event, including ESA’s Envisat, ERS and Proba satellites, the French SPOT series, Canada’s Radarsat, the USGS Landsat and India’s IRS series together with very high resolution data from the IKONOS and Quickbird series supported through the German Space Agency DLR and NASA respectively. Satellite data from before the disaster have also made a major contribution by providing a historical analysis baseline. All data have been given to the relief agencies in the field, with higher-level derived information being developed and made available by image processing and value-adding agencies. The main benefit of the data has been to allow an immediate assessment of the extent of the damage in those areas where local information is either impossible or difficult to access, and to give a more general overview of the affected areas.

This Envisat ASAR multitemporal composite image highlights coastal destruction - including damaged coral reefs - on North Sentinel Island, part of the Andaman Islands in the Bay of Bengal. The colour in the image comes from combining two separate ASAR images acquired on different dates in order to highlight differences between them. The yellow (combining red and green) is matched to a 3 June 2004 acquisition while the blue is matched to a post-tsunami acquisition on 30 December 2004.


UN International Strategy for Disaster reduction: www.unisdr.org

Disasters Charter: www.disasterscharter.org

UNOSAT: www.unosat.org

RESPOND: www.respond.eu.com

CEOS DMSG information server: disaster.ceos.org