Fundamental contents of coastal GIS- the case for a marine cadastre

David Monahan (1), Sue Nichols (2)

(1) Canadian Hydrographic Service, Ottawa
(2) Geodesy and Geomatics Engineering, University of New Brunswick (CA)

As the use of Coastal GIS grows and gains wider acceptance, subject matter experts and their organizations are creating an increasing number of specialized layers. Conventionally, these are used in conjunction with what may be termed "fundamental" layers, such as shoreline, topography and bathymetry. One layer that we believe to be fundamental to all Coastal GIS is one containing legal boundaries, which may be termed the cadastral layer. Although cadastres are well established on land, a great deal of work remains to be done in the marine field before GIS users can confidently rely on a layer containing boundaries. For GIS purposes, a marine cadastre can be defined as a database that would support a GIS layer that at its display level would show the physical locations of boundaries, and at a deeper level would be supported by information on legal and legislative elements of rights, responsibilities, and restrictions to the areas circumscribed by those boundaries. This paper describes the advantages of a marine cadastre and the steps in building one, based on research carried out by our two organizations in Canadian waters.

A marine cadastre would help clarify jurisdictional complexity in Coastal Zones, would provide the basis for identifying and involving the wide variety of stakeholders involved in co-management of Coastal Zones, would be the basis for managing construction of structures and required easements and rights-of- way, and could help prevent ownership issues from becoming contentious. For many GIS users, the ability to call up a fundamental cadastral layer would permit rapid and appropriate application of their special subject matter within a legally defined zone.

Boundaries in coastal areas are frequently confused and overlapping. In part, this reflects the unique nature of the Coastal Zone; for example, cases like that of a moored raft that is under one jurisdiction while floating but under a different jurisdiction when the tide goes out and the raft sits on the exposed sea floor could occur in no other environment. In part it reflects difficulties with legal and legislative terminology: for example, unless specified in the definition, words like "shoreline" and "low water" are open to an array of interpretation. In part, this reflects the fact that few boundaries have been made final through the process of being tested in a court of law (although it must be said that some of those that have been the subject of court cases have not been made any clearer.)

In addition to the need to clarify these legal questions, technical issues that still need to be addressed include: the need to integrate data from diverse sources scattered among departments of all levels of government in a variety of forms and formats without common standards, the need for base data related to the physical space or location of the resources based on full coverage maps of the ocean floor and water column, and the four- dimensional nature of some marine boundaries which have a time varying dimension.

Our research into solving these problems moved out of the theoretical sphere and into that of application through our investigations of boundaries within a Marine Protected Area, the first in Canada to have a Coastal Zone component. In this MPA, boundaries are promulgated from three levels of Government with their attendant regulations, covering topics as diverse as property, rights, environmental protection, resource use, and aboriginal claims. The boundaries are defined in words referring to physical features, some real, some hypothetical, some easily identified, some unknown. The paper explains how we addressed these and structured them into a pilot for a marine cadastre and the boundary layer for a Coastal GIS.