Contribution of Geographic Information Systems in Protection Zones Delineation around a Surface Water Resource in Adzope Region (Southeast of C&amp;#244;te d’Ivoire)

Serge Kouakou Deh,Anowa Evrade Larissa Eba,Kan Jean Kouame,Jacques Edoukou Djemin,Jean Patrice Jourda,Arsene Kpan

doi:10.4236/jep.2017.813102

Abstract

Adzope’s Municipal Artificial Lake which serves as a drinking water supply to the population is prone to pollution due to human activities and increasing urbanization. Thus, it is essential to protect this surface water supply for sustainable use. The objective of this study is to determine the protection zones around this water reservoir in order to preserve the stored water quality. To achieve this, a methodological approach based on a Geographic Information System (GIS) was adopted. This methodological approach first consisted to assess the water reservoir vulnerability to pollution according to certain hydrological parameters (slope, land use, soil type, runoff, and drainage network density) and then to determine the protection zones according to the different vulnerability classes. After the scoring of different parameters, a weight was assigned to each, from the multi-criteria method (AHP). The combination of the weighted parameters in the GIS enabled to establish the water reservoir vulnerability indexes map. The vulnerability map established subsequently presents five (5) vulnerability classes in the watershed: very low (12%) and low (23%) in the North and South of the study area, moderate (32%) disseminated throughout the study area, high (20%) and very high (13%) particularly in the West and North of the water reservoir and in the East of study area. This water reservoir vulnerability map is potentially influenced by the land use parameter according to the sensitivity analysis test. The different vulnerability classes then allowed the delimitation of three protection zones (Zone 1, Zone 2 and Zone 3) around the water reservoir. The immediate protection zone (Zone 1) has a width between 100 and 450 m around the water reservoir with a surface of 1.16 km2. The delimitation of this immediate protection zone takes into account the high and very high vulnerability classes near the water reservoir. The width of protection zone 2 varies from 350 m to 1 km around protection zone 1 with a surface of 5.38 km2. The protection zone 3 covers the rest of the high vulnerability areas contiguous to protection zone 2 with a total surface of 5.69 km2.

Highlights

Access to water in sufficient quantity and good quality for populations has always been a challenge to which the scientific community, NGO (Non-Governmental Organization) and governments participate [1]
This methodological approach first consisted to assess the water reservoir vulnerability to pollution according to certain hydrological parameters and to determine the protection zones according to the different vulnerability classes
Municipal Artificial Lake vulnerability map The water reservoir vulnerability map obtained from the compilation of thematic maps reveals five vulnerability classes (Figure 5)

Summary

Introduction

Access to water in sufficient quantity and good quality for populations has always been a challenge to which the scientific community, NGO (Non-Governmental Organization) and governments participate [1]. Given the diversity and toxicity of pollutant emissions, increasing population and human activities [2], the quality of water resources which are essential to all life’s needs, is threatened In this situation, the competent Ivorian authorities have taken healthy measures through the elaboration of a water code in 1998. The procedure for protection zones establishment usually involves three phases [3] Among these three phases, the technical phase is used to identify places where the surface water resource is exposed to hazards such as pollution related to agricultural, industrial and domestic activities [3]. The population of the study area is supplied with drinking water by a Municipal Artificial Lake or a water storage tank constituted of a dam This water reservoir is threatened by various types of pollution resulting from human activities taking place in its watershed [5].

Objectives

Methods

Results

Discussion

Conclusion