de Jager, A.L., 2015. Feasibility of a worldwide coastal reference and coding system based on the IHO ocean and seas definition.
Coastlines form the geometric basis of common GISs. For example, country borders must match the coastline, rivers flow up to the coastline, and a variety of legislation applies up to a defined distance from the coastline. In this article, we propose a well-defined coastline in a structured GIS format that complies with the International Hydrographic Organization (IHO) ocean and sea definitions. Once this line structure has been defined and digitized to an agreed accuracy, it may be used as a building block—for example, for matching river mouths and country borders to the coastline—and for additional functions such as creating a hydrographic coding system. A coding mechanism has been developed based on available mathematical formulas, which enables the rapid computation of similar codes based on any high-quality geometric data. An application of the system is demonstrated in order to assess how grouping and ordering data along a coastline may be explored. Analysis of the coding system also enables an assessment of how coastline length can be compared with data originating from different sources and/or morphology.