Coastal Zone Monitoring and Management

Context

For millennia, coastal zones of the world have been major centres of human population. For example, in the Mediterranean region 38% of the populations of countries bordering the Sea live in coastal areas. Coastal waters serve as primary routes of transportation and communication amongst these population centres. Many coastal problems that are now being encountered worldwide have resulted from the unsustainable use and unrestricted development of coastal areas and resources. These problems include the accumulation of contaminants and pollutants in coastal areas, erosion, and the rapid decline of habitats and natural resources. In addition to the problems related to unsustainable coastal development, coastal zones can also be significantly affected by the impacts of human-induced climate change. The Intergovernmental Panel on Climate Change (IPCC) estimate that by the year 2100 the sea level will have risen by 31-110 cm. Wetlands are likely to be threatened, coastal erosion will increase, and coastal resources, populations and economies will be adversely affected. In the shorter term, other effects of climate change such as changes in the frequency, intensity and patterns of extreme weather events such as tropical cyclones, intense precipitation, and associated storm surges and flooding are likely to occur.

Coastal development activities such as oil and gas exploration and production, dredging, land reclamation and harbour construction have been well established for many years. In the ten years from 1978 to 1988 there was a 27% increase in oil production and a 20% increase in gas production from coastal areas, and substantial proven reserves have been discovered. Associated with this type of development and other types listed above, there is a corresponding increase of harbour facilities, processing plants, support services and related infrastructures. Whenever there are conflicting interests and competing demands for the use of coastal areas and resources, trade-offs are required between conservation and development, and among various development options.

Contents

Applications of ERS data which can have positive impact on Coastal Zone Management are covered below:

• Detection, monitoring and response to oil spills
• Bathymetric mapping in shallow coastal areas
• Ship detection and monitoring

Other marine information services which are of relevancy to the Coastal Zone: sea state forecasting and nowcasting, the climatology of waves,and navigation through ice are covered in Hazards & Risks in the Marine Environment.The Coastal Zone also encompasses near-shore land, and the use of these areas and of regions further in land is a vital issue in effective management of the Coastal Zone, covered in Monitoring Land Use, Forestry and Agriculture

Detection of oil spills

Illustration: Oil spill monitoring by airborne surveillance (Courtesy Swedish Space Corporation)

One of the most significant environmental concerns worldwide stems from oil pollution. During the last thirty years, pollution of the world's oceans, particularly in coastal areas, has become a matter of increasing international concern. In spite of rigorous controls, deterioration of water quality, especially in waters subject to heavy shipping, continues at a high rate. Due to the relative volumes of discharges, illegal emissions from ships represent a greater long-term source of harm to the environment than infrequent large scale accidents. Monitoring illegal discharges is thus an important component in ensuring compliance with marine protection legislation and the general protection of coastal environments.

Traditionally, this service uses airborne patrols which are expensive and provide often only patchy coverage. Fast delivery SAR products are proving to be of great value in the optimisation of air-borne surveillance resources, due to the large area they can image at any one time.

Experiments show that in general slicks larger than 0.05 km² can be spotted by both aircraft and spaceborne SAR with the same reliability.

Shallow water bathymetric mapping

Illustration: Part of the global GEBCO bathymetry database, for an area off California, acquired using traditional ship survey methods. This picture shows the ship survey tracks. (Courtesy: GEBCO Ltd. and US Geological Survey)

SAR imagery, acquired under suitable ocean current and surface wind conditions allow the bottom topography for an area of tidal sea to be visualised. This imagery are then used to infer bathymetry using a numerical inversion procedure. Combining conventional echo sounder data from a survey track with SAR imagery can shorten survey times considerably, producing a bathymetry map of the required accuracy and thus representing a major saving in costs.

Ship detection in coastal regions

Knowledge of the whereabouts and activities of ships in coastal regions is useful to a range of government and law enforcement agencies, such as those concerned with enforcing legislation regarding fishing activities in Exclusive Economic Zones, and environmental protection agencies to support pollution control. The information is also of use to coastguard for use both in search and rescue operations and in law enforcement activities, to supplement land-based coastal surveillance radar which has a maximum range of under 100km.

It has long been recognised that this satellite-based radar has the ability to detect and monitor vessel traffic. Due to the nature of the radar, monitoring can take place through cloud cover and at night thus proving an advantage over optical data. As well as detection of vessels it is possible to derive various characteristics of each vessel such as location, speed, heading, and broad class of vessel.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry