Introduction
Increased industrial activity, international trade, natural resources extraction and population pressure correspond to an increase in the pressure on natural and human environments in the coastal zones of the world.
These pressures include increased air, water and soil pollution and consequential habitat destruction. Degradation can be slow and continuous, or can take place during sudden unfortunate events involving hazardous materials or oil and chemical spills and leakage.
Keeping in mind the complexities of the natural environments and the broad range of potential threats it is apparent the remaining unexploited areas will come under increased pressure.
Sweden has a long coastline and large archipelagoes. The sensitivity of the various coastal eco-systems have been studied for many years and a range of steps have been taken to protect sensitive coastal resources by legislation, public awareness, control and the creation of an abundance of conservation and protected areas.
In tropical countries, besides the persistent hydrocarbons and toxic metals, matters that have the greatest potential impacts on the environment are in most cases different. Generally, the most important threats to man and the bio-diversity and productivity of the ecosystems of the tropical environment are:
- physical destruction, cutting of coastal vegetation or other destructive methods of extracting the resources.
- siltation and sedimentation from poor practices in agriculture and forestry causing decreased productivity.
- microbial and viral pathogenic pollution causing problems to aquaculture and fisheries.
- blooms of toxic microorganisms that also affect fisheries and aquaculture
- release of nutrients and organic matter from land causing eutrophication on nearshore environments.
For coastal resource environment planning and management including physical planning it is vital to have access to accurate baseline environmental data and systems defining the relative sensitivity of various coastal resources.
Swedish companies have developed systems for classification, storage, analysing and displaying coastal resource data using GIS and remote sensing techniques. Using a sensitivity index system (physical, ecological and human-use features) the modelling of the GIS database will produce a variety of thematic maps including environment sensitivity (ESI) maps.
GIS Database for Coastal Resources
For an assessment of coastal environment sensitivity the first step is to logically organise, classify and structure all coastal resource data in a database. GIS tools are used for digital processing and organising of all geographical data of interest:
- Shoreline features
- Biological (ecological) features
- Human-use features
- Geographic base information
GIS is a set of computerised tools for capture, storage, edit, retrieval, analysis, update and presentation of information for a particular purpose. Database information can be retrieved from PC platforms preferably using the ArcInfo and ArcView softwares.
As database work is time consuming it is essential to use existing analogue and digital data as far as possible. However, existing data can vary in standard, classification, accuracy and scale. To harmonize existing data into a common quality and standard becomes a major task. This is done by using remote sensing techniques, satellite images and on-screen interpretation/correction methods.
Remote Sensing
Mapping and presentation of new spatial data as well as updating of existing geographic information have traditionally been time consuming and expensive tasks. In several countries thematic maps do not cover the entire territory or, if they exist, may be outdated. Satellite remote sensing technology is therefore a valuable tool for gathering up-to-date information regarding the coastal zone environments all over the world.
Using SPOT or Landsat imageries, interpretation keys have been established for a range of coastal features. Effective and rewarding use of the remote sensing approach can now be achieved after years of actual experience of satellite imagery interpretation combined with extensive ground-truth verification work in coastal zones.
Methods for verifying, complementing and harmonizing existing databases (analogue and digital) on screen using remote sensing and pre-processed geo-referenced satellite imageries have been developed. Corrections can include the addition of incomplete coverage, change of classification, modification of geometry.
Environment Sensitivity Index and Sensitivity Modelling
An Environment Sensitivity Index (ESI) is a ranking of the environment sensitivity of shoreline segments and other features in the coastal and marine zone. Using GIS tools the ESI is applied to the coastal resource database creating ESI maps. Potential purposes for developing and applying an ESI to a coastline are many, including risk assessments for industrial activities, impact assessment for proposed development, physical planning, oil spill contingency planning etc.
The ESI arranges shoreline types into 5-10 sensitivity categories. Certain formulas also incorporates the socio-economic and ecological impact on the ESI .
Example of a five- ranking level sensitivity ranking system
| Sensitivity – ESI* | Coastal Resource Classification | Shoreline Classification |
| High | Mangroves Freshwater Marsh Saltwater Marsh Dense Agriculture – Rice Dense Agriculture – Mixed Aquaculture Village |
Sheltered – Coarse sand beach Mixed sand/gravel beach Gravel beach |
| Medium-High | Mud Flat Salt Pan Lagoon Small River and Stream Broad River Fresh Water Body Urban Area |
Medium – Coarse sand beach Mixed sand/gravel beach Gravel beach Sheltered – Silt/mud beach Sheltered – Rocky shores Tidal flat Fine grained sand beach |
| Medium | Forest – Dense Sedge Plantation Sparse Agriculture Industrial Land Commercial Harbor Airport |
Medium – Silt/mud beach Tidal flat Fine grained sand beach Cliffs Rock wave-cut platform Human modified beach Exposed – Coarse sand beach Mixed sand/gravel beach Gravel beach |
| Medium-Low | Sand Flat Forest – Sparse Grassland/Bushland |
Medium – Rocky shore Cliffs Rock wave-cut platformHuman modified beach Exposed – Silt/mud beach Tidal flat Fine grained sand beach |
| Low | Barren Land | Exposed – Rocky shore Cliffs Rock wave-cut platform |
Coastal Environment Sensitivity Index, ESI
The sensitivity ranking may change taking into account coastal resources that are of especially high value or significance, such as rare or endangered species, environmental protection areas, and tourist spots.
Thematic Mapping
Map preparation and map production is often an integral part of establishing and developing GIS databases. The digital interface and map window of a GIS has many advantages with its fast viewing, zooming and panning tools, and the ability to manipulate the mapping product directly on-screen. However, traditional maps are beneficial when it comes to effective spread of cartographic information. Printed maps can be separated into two categories: simple map printouts ordinary map printouts
Simple map printouts refer to easy and quick printing of thematic maps for a variety of purposes. Ordinary maps refer to more advanced and standardised products with pre-defined content and pre-set scales and formats. National survey maps often forms the basis for the layout of this type of maps. Coastal resource maps, Coastal sensitivity maps and Field inventory base maps are produced in scales 1:50 000 and 1:100 000.