An integrated GIS methodology for the determination and delineation οf juridical bays

Highlights

• The paper presents a methodology and application for the detection of juridical bays.

• It examines the formation of bays for the totality of points comprising the coastline.

• It determines all indentations that are entitled to be closed as bays in the legal sense.

• It achieves the maximization of the bay's area.

• It addresses the problem of islands in mouth for which it maximizes the enclosed area.

Abstract

One of the fundamental concepts of the Convention on the Law of the Sea is that of the baselines, where from the breadth of the maritime zones is measured. Baselines, delimiting the land and internal waters from the sea, can be any combination of normal, straight, archipelagic or bay-closing lines. The determination of the coastline indentations at which the coastal State is entitled to draw bay-closing lines has been a complicated and time-consuming task. Existing GIS environments carry out the process semi-automatically with the user undertaking the location of the candidate indentation and the software validating the length and semi-circle criteria stipulated by the Convention. This process has the inherent weakness that indentations meeting both criteria may remain undetected. This paper presents, implements and evaluates a methodology for the determination of all indentations along the coastline that can be closed with bay-closing lines without the intervention of the user. The proposed methodology addresses the issue of juridical bays in its entirety, including the existence or absence of headlands, the presence of islands in the mouth of the bay, as well as the maximization of the area of the bay, something that currently available solutions are lacking in.

Introduction

The 1982 United Nations Convention on the Law of the Sea (hereinafter: UNCLOS) (UN, 1982) comprises the legal framework governing relations between countries at sea. In its 320 articles and 9 annexes it codifies, amongst others, the different categories of maritime zones, provides the framework for their delimitation, unilaterally and bilaterally, as well as the competences of the coastal States on them. One of the fundamental concepts of UNCLOS is that of the baseline demarcating land and internal waters from the sea, which constitutes the reference where from the breadth of the maritime zones is measured.

Under normal circumstances the baseline coincides with the low-water line, known as natural or normal baseline, ‘as marked on large-scale charts officially recognized by the coastal state’ (UN, 1982, Article 5), but can be any combination of normal, straight, archipelagic and bay-closing lines. Straight baselines may be used in localities ‘where the coastline is deeply indented or cut into, or if there is a fringe of islands along the coast in its immediate vicinity’ (Article 7(1)). The concept of straight baselines was introduced into the international law with the judgement of International Court of Justice (ICJ) over the Anglo-Norwegian case and the delimitation of the fisheries zone between the two (ICJ (UK v. Norway), 1951), which later bequeathed to UNCLOS. Nonetheless, UNCLOS does not set specific rules for the implementation of straight baselines and even though States have incorporated standards applying such rules (e.g., USA [USDOS, 1987]), something of the kind has not been internationally agreed to date. As a result, the system of straight baselines is often treated as an ‘exception to the normal rules for the determination of baselines … which must be applied restrictively’ (ICJ (Qatar v. Bahrain), 2001). Unlike straight baselines, Article 10 of UNCLOS sets two objective criteria for the implementation of bay-closing lines, namely the criterion of length and that of the semi-circle. With regard to these two criteria, the length of the bay-closing line must not exceed 24 nautical miles (NM) (Article 10(4)) and the enclosed water area must be at least as large as that of the semi-circle the diameter of which equals the length of the closing line (Article 10(2)). When these two criteria are met, the sea body landwards comprises internal waters, which are under the full sovereignty of the coastal State and the bay-closing line becomes part of the ‘baseline system’. Otherwise, the bay is not considered to have legal status and the coastal State is not entitled to close it.

The correct delineation of bay-closing lines and the overall construction of the baselines, where from the breadth of maritime zones is measured, have a significant impact on the efficient ocean and coastal management of living and non-living resources as well as on other sensible cartographical issues. An illustrative example constitutes the responsibility for the production of a seamless Electronic Navigational Charts (ENC) database, a task that the Member States of the International Hydrographic Organization (IHO) assumed after the International Maritime Organization (IMO) set the carriage requirements in Regulation V/19.2.1.4 of the SOLAS Convention (IMO, 1974).

This paper delves into the problem and contributes to its solution by suggesting, implementing, evaluating and validating an automated methodology for the identification of all juridical bays along the coastal State's coastline, aiming at the uniformity and the integrity of the results. This study is the first stage of an extended research programme on the delineation and delimitation of maritime zones, which aims at the improvement of the overall quality of the results and the support of cartographers' work. It includes the development of a methodology in a GIS environment for the automated delimitation of the median line between two or more States, irrespective of the type of baselines.