erocips

At present, within EHS’s Coastal Survey GIS, the coastline has been divided up into approximately 100 sections. Substrate types within each section have been identified and digitised on map, however, more granular analysis is required to allow for the location of (and therefore different level of response to) specific coastal assets. For example, marinas or harbours, along each section would need to be treated differently than the remaining coastal section area.

Therefore the decision has been made to develop a raster model with a grid cell size of 100x100m2. This raster model would involve converting the current coastline layers into raster datasets that would then be used as the template for scoring through the generation of a GIS model involving many vector datasets developed as part of the NI Coastal Contingency Plan project.

It is proposed that the development of such a Model would utilise the ArcGIS Model builder extension functionality already present within ArcGIS and would have similar concept/plan to models being developed elsewhere within EHS, for example, the WMU Abstractions assessment tool. In addition, the extension to ArcGIS, Spatial Analyst, will also be utilised.

It is envisaged that the Model would be accessed through ArcGIS and stored in ArcToolbox or perhaps in a spatial database.

Model inputs could include a wide range of EHS vector datasets including Natural Heritage, Built Heritage and generic EHS datasets as well as any external consultants data including Oil Map data etc.

The model will essentially involve integrating various geo-processing steps required in the scoring or prioritising of the coastline. These would typically include spatial joins and proximity checks across a wide range of vector datasets already held in databases throughout the EHS. This would involve running proximity analyses on, for example, geologically or archaeologically important features or areas of important natural habitat etc.

Once the model has been built and all of the relevant geo-processing stages have been set in place with inputs and parameters established, a simple mathematical calculation or reclass tool would be used to determine the final (or perhaps intermediary) sensitivity score for each 100 square meter cell (or section of coastline).

It will be possible to vary the scoring methodologies so that existing layers could be reweighted or even allow for the introduction of new layers not already considered in the model. For example, a ‘commercial value’ layer (perhaps containing approximate valuations of commercially valuable assets along the NI coastline) could be given greater or lesser weighting by the model, for example the changing sizes of bird populations according to the season in important bird breeding/overwintering areas.

Variations in result could be represented through a series of thematic raster layers within GIS which would illustrate the impact of changes in methodology or input data to the level of response required along the shoreline.

It is envisaged that such illustrative results and scientific methodology in approach to this issue would help greatly in the consultation process EHS are required to undertake in 2007 and ultimately in planning coastal incident response.