---information is the currency of the 20th century---
Better information for better management

Remote sensing systems, used to observe the Earth's surface from satellites and aircraft, make it possible to collect and analyse information about resources and land use over large areas. Geographic information systems (GIS) allow resource managers to process large volumes of geographically referenced data from multiple sources. These data can be integrated to produce maps, monitor changes in resources and model the impacts of management decisions.

Remote sensing and GIS are technologies whose potential has yet to be fully explored. Nevertheless, many resource managers in both developed and developing countries have already benefited from these technologies in fields such as town and country planning, watershed management, agriculture, forestry, conservation, mineral resource development and prevention and mitigation of natural disasters.

Remote sensing and GIS are complementary technologies. A GIS can be used to interpret remote sensing data more accurately by integrating them with data derived from other sources and can analyse large volumes of geographically referenced data that would be overwhelming to process manually. On the other hand satellite images can help to update efficiently certain data layers in the GIS.

Remote sensing

Remote sensing is the technology allowing to obtain information of an object, area or phenomenon by means of data coming from an apparatus, which is not in physical contact with this object, area or phenomenon. In practice, this means that the information of the Earth's surface is obtained by sensors mounted on an airplane or a satellite. Most remote sensing satellites are in polar orbit (about 900 km from the Earth), while communication and some weather satellites are in geostationary orbit (about 36,000 km away from the Earth).

Remote sensors record electromagnetic radiation emitted or reflected from the Earth’s surface. Different types of vegetation, soils and other features emit and reflect energy differently. This characteristic makes it possible to identify different cover types on the surface. Using multi-temporal images it is possible to monitor the changes. Finally, since the images are digital they can then be re-formatted to constitute an accurate geometrical representation of the earth, in other words the creation of accurate maps is possible using satellite images.

Stages of Remote Sensing (Source : Natural Resources Canada).

Energy Source or Illumination (A)
Radiation and the Atmosphere (B
Interaction with the Target (C)
Recording of Energy by the Sensor (D)
Transmission, Reception, and Processing (E)
Interpretation and Analysis (F)
Application (G)

Planet earth is actually surrounded by about 40 earth observation satellites. A large amount of satellite remote sensing data is currently available from a number of agencies.

With remote sensors it is possible to update data more frequently than ground-based survey techniques and, in theory, to monitor changes occurring in features in near-real or "real enough" time. With frequently updated information, resource managers can monitor dynamic processes. In some places, they have to make decisions about isolated and sometimes inaccessible areas.

In such cases the analysis of remote sensing data is the way to acquire the most accurate, inexpensive and timely information needed to identify and assess different management options.

Different types of spatial and spectral resolutions are available. Very high ground resolution is the new generation of sensors with 4 m in multispectral mode and 1 m in panchromatic mode for Ikonos and 2.8 m in multispectral mode and 0.7 m in panchromatic mode for QuickBird. These systems enable users to discriminate a greater number of features more quickly, they enhance decision making in fields such as natural resource exploration, city planning, vegetation monitoring, detection of pollution, disaster and crisis mitigation and economic analysis. Simultaneously, research continues into new ways in which remote sensing technologies can be used to facilitate strategic planning for environment and development issues.

GIS

A geographical information system is a database that has the main characteristic that all objects of the database have a geographical reference. Therefore all data coming form this particular database can then be displayed in the form of maps. A geographic information system (GIS) is a combination of hardware, software and procedures for storing, managing, processing and reproducing spatial data with data coupled to them. The data can be obtained from ground surveys, GPS measurements and from remote sensing data.

A computerised GIS allows managers to perform complex analyses by overlaying and displaying large volumes of spatial and non-spatial data. Spatial data pinpoint the location of features on the Earth's surface like a river, a well or a political district. Non-spatial data describe features such as the pH and temperature of the river at a monitoring station, the date the well was dug or the name of the political district.

A range of GIS computer systems hardware and software is now available and the choice can be made according to:

• the type of data being analysed (which determines the sophistication of the equipment needed to enter the data);
• the amount of data to be stored (which determines the amount of storage space required);
• the type of analyses to be performed (which determine the analytical software needed);
• the kinds of maps, tables and charts that need to be created (which determine the hardware and software needed to display or print them).

Use in resource management

A GIS can help managers to perform many routine and complex tasks. For example, a GIS can be used to:

• Analyse spatial relationships: e.g. estimate the number of people living within a floodplain.
• Identify regions that meet multiple criteria: e.g. identify lands that would be suitable for specific agricultural crops or transportation routes that would balance the need to minimise construction costs with the need to serve a maximum number of people.
• Model the impacts of policy options: e.g. predict the amount of erosion that would be likely to occur if an area were to be deforested.
• Measure and monitor dynamic processes, when used with remote sensing data: e.g. measure crop yields, city expansion or changes in a coastline, measure subsidence of buildings in cities, etc.

GIS analyses are usually more cost-effective, accurate and faster than manual analyses in situations involving large amounts of diverse data, such as thematic maps, remote sensing data, statistics and texts.

More information can be found on the BEO (Belgian Earth Observation) website at http://eoedu.belspo.be

Remote sensing and World Heritage

Remote sensing offers many useful and sometimes indispensable data for the mapping, monitoring and management of World Heritage sites, either natural (parks, landscapes...) or cultural (monuments, archaeological sites...).

However, remote sensing or GIS cannot substitute the monitoring process that is required for the good conservation of World Heritage sites. GIS and Remote Sensing are excellent tools to support this process.

The entire surface of the Earth, including the most remote and inaccessible places can be observed by satellites. Satellite images can be obtained in digital form (so directly workable by computer processing) and provide reliable, repetitive, non-invasive, rapid and cost-effective information, and this from a unique viewpoint.
Satellite images can be used to:

• create up-to-date maps;
• help to delimitate management zones for conservation purposes ;
• monitor land cover and vegetation change ;
• • assess damages caused by natural and/or human hazard ;
• • assist in the identification and precise location of sites in the world that have certain characteristics so that they could become World Heritage sites if the associated country so desires.

In some areas an absence of recent maps of World Heritage sites (e.g. Virunga, Niokolo-Koba, Ha Long Bay) exists. For these areas, which are often not easily accessible, a recent satellite image coverage can be useful to produce new GIS layers providing the required information for a beneficial protection management of the site.

Frequently the information on boundaries of some sites and their buffer zones (e.g. Virunga) or on the new built-up expansion (e.g. Ha Long Bay) is not readily available, though can be clearly demarcated on satellite images.

Virunga National Park boundaries.

Ha Long Bay built-up expansion.

Digital maps can be realised by combining satellite imagery and ground control points obtained by geo-positioning systems (e.g. GPS). Stereoscopic views permit to obtain a digital elevation model of the landscape or some three-dimensional measurements of monuments.

Satellite images can put in evidence vegetation changes (degradation of certain vegetation types, fragmentation, conversion from forest into agricultural land, recovery,…) as well as phenomena or processes such as deforestation, urban expansion, marine pollution and so on.

Satellite images are also useful to, in some cases, identify areas that could be affected by certain natural hazards (forest fires, oil spills, flooding, etc.), in general monitor natural and human disasters, or assess the resulting damage. In the Southeast Asian region images provided by SPOT, ERS and RADARSAT satellites are being routinely used to monitor forest fires and ocean oil pollution. Burnt scar maps have been generated based on SPOT images. In cloud-covered areas, Interferometric Synthetic Aperture Radar (SAR) data from the ERS-1/2 tandem mission is used to complement the optical imagery in assessing burnt areas. ERS and RADARSAT SAR images are as well useful in the detection of oil slicks.

Remote sensing offers useful data for the investigation of archaeological sites. Some were even discovered by means of remote sensing (e.g. the Lost City of Ubar revealed in 1992 on the Arabian Peninsula). Satellite images allow finding unexcavated vestiges by exploring large areas in a very short time. Only selected zones will be further examined.

The advantages of GIS and remote sensing for World Heritage Conservation are various:

• They become a valuable tool to assist conservation activities.
• All information is exactly localised and gathered in one tool.
• Information can be continuously updated.
• Better decision making by spatial analysis.
• Possibility of direct extraction of topographic and thematic maps for terrain use.
• Digital handling of data.

Today we live in a global village. Events and news from the other side of the world reaches us instantaneously and influences our lives. Information goes around the world and information makes the world go around: gathering, collection, analysis and distribution of information marks the current era, the information age. At the same time, an increasing global concern for conservation of the world heritage arises. The time has come to provide assistance of countries willing to protect their World Heritage sites through these technologies.