REMOTE SENSING SUPPORT FOR ANALYSIS OF COASTS
An exciting new project, recently launched in Israel and Europe, promises to advance coastal management along Israel’s sensitive Mediterranean coastline and to serve as a case study for other coastal zones. The RESSAC project , acronym for Remote Sensing Support for Analysis of Coasts, was officially launched in March 1997 within the framework of the European Commission Programme on Environment and Climate 1994-1998 (Contract # ENV4-CT96-0369). Although remote sensing projects have been implemented before, RESSAC is deemed to be one of the most ambitious projects yet and the first in Israel to utilize funds provided by the European Commission.
The project itself was first conceived by the Regional Activity Centre for Environmental Remote Sensing (RAC/ERS), within the framework of UNEP’s Mediterranean Action Plan (MAP), in coordination with the Israel Ministry of Environment. In 1996, a joint proposal was submitted to the European Commission. Subsequent approval of the proposal, which is largely funded by the Directorate Generate for Science, Research and Development (DG12), paved the way for the landmark two-year undertaking in which several European and Israeli partners are actively involved.
Several factors combined to facilitate the decision to implement the project. First, the plan is fully in line with the European Commission’s decision to launch a demonstration programme on Integrated Coastal Area Management and engage in preparatory activities on coastal monitoring in the framework of the Centre for Earth Observation (CEO), and the Marine Science and Technology Programme. Second, the project fully accords with the priority requirements of Mediterranean countries as these are expressed in MAP. Third, the project advances Israel’s current plans for coastal protection and is an important constituent in the Israel CAMP (Coastal Areas Management Programme) agreement which was signed by MAP and Israel in November 1996. Fourth, the program contributes to CEO objectives by widening the use of remote sensing and allowing the results to be demonstrated to other potential EU customers.
The RESSAC project is coordinated and managed by CTM – Centro di Telerilevamento Mediterraneo of Italy in its capacity as RAC/ERS and includes the following additional partners, each of whom has a different expertise:
Ministry of the Environment (Israel)
ARGOSS – Advisory and Research Group on Geo Observation Systems and Services (Netherlands)
NLR – National Aerospace laboratory (Netherlands)
Nuova Telespazio (Italy)
Israel Oceanographic and Limnological Research (IOLR) (Ministry of the Environment Associate Partner)
Geological Survey of Israel (GSI) (Ministry of the Environment Associate Partner).
Objectives of the Project
Worldwide, the coastal region is characterized by intense activity and by an interchange within and between physical, biological, social, cultural and economic processes. Coastal areas comprise many interacting systems: maritime, terrestrial and riverine. Changes in any part of the system can generate chain reactions far from their point of origin and may even alter environmental conditions in a totally different system.
These and related issues are especially relevant to the coastal zone of Israelthe most densely populated region in the country. While recent findings have demonstrated that the Israeli coastline is in negative sedimentological balance, a comprehensive methodological and quantitative assessment of the damage caused to the coast and its erosional processes has never has been undertaken. Therefore, a methodological approach which will integrate "conventional" geological and oceanographic studies with the analysis of satellite data is expected to provide useful information for the assessment of coastal erosion processes.
The RESSAC project will attempt to demonstrate the usefulness and cost-effectiveness of multi-satellite based data in the assessment and monitoring of coastal erosion phenomena and processes in Israel by developing a "prototype" information system containing enhanced Earth Observation products. The outcomes of the project will contribute to the evaluation of the present coastal state and its most recent evolution, to the assessment of coastal vulnerability to erosion and, most importantly, to the integration of remotely sensed and other information in the decision making process on coastal planning. Implementation of the project will promote the introduction of advanced tools to the Planning Department of the Ministry of the Environment for application to methodologies utilizing Earth Observation data, for on-going and future activities, and especially for coastal monitoring and follow up on the impact of future interventions along Israel’s coasts. The project is also expected to contribute to the CEO programme by providing information, methodologies and demonstrations which will be useful for its development as well as for the design of additional programs in other coastal zones. Since the project involves groups from several European and Mediterranean countries, electronic facilities using standard communication channels (e.g., Internet) will be developed to promote data exchange (numerical, textual and graphic). The data network will also interact with the CEO network for European users of remote sensing data which is presently being developed.
The integration of data from different satellitesoptical and microwaveis expected to prove particularly useful and will ultimately contribute to the introduction of new customers to the usage of remotely sensed data. The project is focused on monitoring and studying the following aspects, all of which are relevant to a better understanding of the coastal erosion process in the test area:
– shoreline changes
– coastal land cover
– bathymetry assessment
– suspended sediments analysis
– sand inventory
– sea-state and wind.
Coastal Erosion Assessment
Coastal erosion has been identified by Israel as one of the main issues which must be tackled in order to provide an accurate definition of the environmental state and resources of the coastal area.
Recent findings in the nearshore zone and inner continental shelf of Israel have confirmed that the Israeli coastline has a negative sedimentological balance. While coastal erosion is caused by the long-term Holocene transgression, it has been greatly aggravated by human activity which disturbs the natural dynamic beach accretion and erosion processes and exposes the coastal kurkar cliffs to accelerated abrasion. Two main types of anthropogenic interferences have been known to disturb the natural sand transport on the Israeli coastline: sand, sandstone and beachrock quarrying for building purposes and construction of shore installations such as ports, harbors, marinas and breakwaters. While various approaches have been taken to estimate the coastal changes and processes (e.g., comparison of aerial photographs of the same section of a coastline and kurkar cliff edges taken at different periods), studies carried out so far have never been integrated to provide an overall view of the damage caused to the coast nor has the research been fully methodically and quantitatively assessed.
In view of the activity taking place on the Israeli coast, a policy on sand use is being formulated. Recent findings have resulted in a debate on whether to build more marinas and other marine and offshore constructions. For the purpose of decision making, the Ministry of the Environment has launched a proposal to implement several programs related to coastal dynamics which affect land-use planning along the coastline. These include:
– Monitoring of coastal sand resources as a national commodity, based on clearly defined policy, data on sand availability and properties, numerical models of expected changes and a monitoring program;
– Management of responses to climate change in relation to possible impacts on beaches and marine structures;
– Management of coastal cliff instability in connection with coastal sand resources, frequency of instability and alternative measures for stabilization;
– Implications of sand management for coastal land use planning, particularly in relation to recreational use of beaches, marine structures for water sports, urban and tourist development of coastal sites and future ideas for offshore islands, beach renourishment and land reclamation.
The outcomes of these programs should provide a basis for a national coastal protection policy and for decisions at local level on individual projects. All these programs currently depend on the acquisition of data on coastal characteristics and changes based on marine (oceanographic, sedimentological, biological) and land (geological, geomorphological) surveys with in-situ sampling, aerial photogrammetry and use of models for the integration of data and forecasts.
However, the expense and time required to implement traditional surveys has often resulted in the absence of updated temporal and spatial data which are vital for decision making. Moreover, in order to assess the vulnerability level of a given coastal strip, and consequently its present trend toward erosion or accretion phenomena, various integrated observations and analyses are essential. The addition of satellite remote sensing to traditional methods would make it possible to obtain updated information on wide marine and land areas in a more efficient manner, thus allowing for continuous monitoring of their trends.
The integration of data provided by different satellitesoptical and microwavewhich have complementary geometric and temporal resolution for the observation of the extent and dynamics of a phenomenon, is particularly powerful. In particular, the data provided by optical and microwave sensors are useful for the characterization of the morphology of the coastline and of the sea platform, for the assessment of land use and its most recent changes, as well as for the characterization of the sea-state and other dynamic feature of the sea platform, in particular relevant to the distribution of currents and sediment transport. Such information is necessary for the assessment of coastal erosion and its related phenomena.
The RESSAC project will use both space and non-space data in order to facilitate the production of a vulnerability map of a section of Israel’s Mediterranean coastline. Space data will include:
ERS SAR, altimeter and scatterometer
Data Integration and Contribution to Decision Making
Databases are essential tools for the integrated management of coastal and marine resources. They reduce uncertainty and provide decision makers with ways of identifying relevant coastal issues, reviewing the impacts of alternative actions and providing information on present and expected costs and benefits.
The most common uses of a database in a coastal management process are:
– Identification of the key indicators of existing conditions to the present state of the coastal environment;
– Identification of coastal resources under stress or at risk, and their level of vulnerability or risk or degradation;
– Forecasting of the possible impacts of alternative development trends on sensitive resources;
– Identification of areas of opportunity, using site suitability and exclusion criteria;
– Simulation and testing of alternative options;
– Monitoring and feedback;
– Exploration of available information and alternative scenarios through interaction tools with query capabilities.
An essential component of data management for integrated coastal management is the compilation of the data on physical/natural resources and economic information. In this context, the Geographical Information System (GIS) has emerged as one of the basic tools for data integration as well as for the analysis and management of land resources. The GIS is characterized by its ability to handle geographical datawhich can be displayed as map imagescapable of integrating environmental, social and economic data into a single system.
Nevertheless, the implementation of an "image-based" GIS is still new and such an implementation depends not only on the further development of the technology but also on an increased understanding of how such systems will be used and may be integrated into information support systems, including spatial decision support systems.
In the framework of the RESSAC project, the GIS unit in the Ministry of the Environment’s Planning Department will play an essential and active role, focusing on the organization, management and integration of environmental data relevant to the coastal erosion issue. The system will help the Ministry of the Environment to identify some key indicators of existing instability conditions in the test area, to define the level of vulnerability and degradation of coastal resources and to provide new integrated tools for monitoring the evolution of a specific phenomenon. A special effort will be made to set up procedures to allow the integration of data derived from the different remote sensing platforms and in- situ ones to provide combined information. Such combination of data will allow the gathering of information on the environmental conditions in the area under examinationsea-state, exceptional events, bathymetry, sediment pattern, sand inventory, coastline changes. Furthermore, methodological research will be carried out concerning the classification of the selected coastal area according to its vulnerability to erosion. The RESSAC project will attempt to define the vulnerability of the selected coastal area by using the combined information produced by the integration between remotely sensed information and in-situ data. The production of such a map should be very useful for the proper planning and management of the coastline in the selected area and should represent a new tool which the Ministry of the Environment can apply to the planning of other coastal areas. Another output expected from such a demonstration is the definition of a proper monitoring plan of the selected area which could combine satellite and in-situ measurements.
The Planning Department of the Ministry of the Environment will thus play the double role of both customer and full partner in the RESSAC project. It will participate in all stages of the project from the initial definition of the information requirements, to the provision of existing information, to the evaluation of the reliability and potential cost effectiveness of the use of Earth Observation in this application, to cooperation in setting up the final results.
The final result of the proposed project will generate benefits for all the partners: Israel will profit from the new supports which will provide more comprehensive and updated environmental knowledge required for prompt decision making on coastal projects; the cooperating partners will gain an opportunity to further develop their expertise; and the data providers and space agencies will have an impetus for widening the use of remote sensing.
Acknowledgment: Special thanks to Mr. Yari Ginott, head of the Ministry of the Environment’s GIS Unit, for his help in preparing this paper.