Towards an Operational Segmentation of the Colombian Caribian Coastal Zone

Luis Borda (1), Jacques Denis (2)

(1) Faculty of Environmental Methods and Science , ENAC, LaSIG. - Polytechnical Federal Institute of Lausanne (EPFL) (CH)
(2) Coastal Environment Division (DELL), French Research Institute for Exploration of the Sea - Direction de l'Environnement et de l'Aménagement littoral, Institut Français de recherche pour l'exploitation de la mer (IFREMER) (FR)

The implementation of an Integrated Coastal Zone Management (IZCM) process, requires the definition of geographical spatial units in order to form as many territorial (or observational) units as possible within which the different interested parties may find a favourable framework for communicating, retrieving and exchanging information-indispensable for the rational management of the coastal area. These territorial units facilitate data and information management, of interest for the establishment of an inventory and diagnosis of the quality of the coastal area.

The Caribbean sector of the Colombian coast was divided into units in order to partake in the elaboration of a geographical reference system that is commonly used for monitoring and evaluating coastal water quality. The main purpose of such referencing is to structure all data necessary for analysis, as well as to establish the appropriate monitoring means, in coherence with the existing management rules.

Based on a logical process, the coastal zone was divided according to three main criteria : administrative boundaries, natural ecosystem boundaries and existing problem boundaries. These criteria have often been considered as being independent from each other. For monitoring and evaluating coastal water quality, the question remains as to which variables and division procedure must be used. Two approaches are possible: the objective and the subjective approaches.

The objective approach implies taking into account all variables essential for determining each unit of observation from environmental, physical, economic and social viewpoints. This approach is considered to be objective insofar as it results from a methematical calculation. Nevertheless, the attribution of a weighted value to each of these retained variables could be introduced to make sure that the observed tendencies work

The subjective approach calls for the experience and/or knowledge of coastal zone experts, essential given the lack of general knowledge of the entire coastal area . This approach is subjective because the result will vary not only according to the retained variables, but also according to expert opinion.

Given that neither of these approaches reflects the reality, the combination of both approaches, called a " mixed approach" was adopted within the framework of this dividing exercise. On the one hand it calls for all available and necessary information, and on the other hand, for expert knowledge, having the function of analysing, verifying and validating the results. The expert function was fulfilled by twenty or so people currently working in institutions directly related to Colombian coastal zone management. The approach stated above has the advantage of being a compromise between the different variables retained and the management and monitoring objectives set forth. This compromise mainly allows for the association of each defined territorial unit to all given information necessary to obtain a synoptic vision sufficiently complete in order to apprehend the different set of problems and to elaborate coherent management rules, while favouring the best consensus between economic activities and environmental protection.

To achieve the fixed objectives, the following steps were realised:

1. Evaluation of variables: what is the necessary information that is available and susceptible to being used?
2. Retained variables: Among the available information, which is the most relevant for defining marine, terrestrial, as well as transversal limits along the coastline?
3. The GIS: what is their role and their effective contribution?
4. Expert validation: Are the variables retained the most appropriate and do they respond to the fixed objective?
5. Division: application and brief presentation of the defined units.
6. The cartographical scale: to which cartographical scale must the deduced units be represented?

A questionnaire aimed at evaluating the methodology used as well as the results produced, allowed the group of experts to express themselves during the feedback phase, in such a way as to enable the demarcation of 13 units on the Colombian Caribbean which aim to monitor and evaluate the quality of coastal waters within a general framework of the management of this zone.

At present these results are the object of an evaluation conducted by INVEMAR (Institute for Marine Research), which, in collaboration with IDEAM (Institute of Hydrology, Meteorology and Environmental Studies) is entrusted by the Colombian Minister of Environment to prepare and define the future National Coastal Information System (SIC). This tool will constitute the working platform, indispensable for supporting the various research projects, in keeping with the integrated management process of the coastal zone.