Avaliação da vulnerabilidade das águas subterrâneas à poluição no município de Tabarre, região metropolitana de Porto Príncipe – Haiti

Abstract

The municipality of Tabarre is located in the aquifer of the Cul-de-Sac Plain (PCS), which is used for public supply to the metropolitan region of Port-au-Prince, Haiti. The municipality is going through an intense population increase, accompanied by a disorderly urbanization, especially after the impactful earthquake that occurred in 2010. The objective of this study was to evaluate the vulnerability of groundwater to pollution in the municipality of Tabarre, using the DRASTIC method, which makes use of a parametric system of 7 variables, culminating in the organization of a cartographic product. The methodology had four stages of development, which involved data acquisition (1), processing and analysis of groundwater samples (2), determination of the DRASTIC index (3); and the mapping of the vulnerability to groundwater pollution in Tabarre (4), using the QGIS software at a scale of 1:50,000. The waters of 15 boreholes were evaluated based on physicochemical and bacteriological parameters. Based on the criteria of the WHO and the EU, the results acquired for the physicochemical parameters are in accordance with the standards. However, the bacteriological parameters are not adequate due to the presence of total coliforms, which ranged from 2 CFU/100 mL to 22 CFU/100 mL in the P3, P5, P6, P8, P9, P10, P11, P12 and P15 holes. In addition, fecal streptococci reached values of 4 CFU/100 mL and 3 CFU/100 mL in samples from P9 and P10 holes. Among the 15 holes, 9 of them presented some inadequate bacteriological result. The map presented four classes with different degrees of groundwater vulnerability: low (< 108), medium (108 to 140), high (140 to 200) and very high (> 200). The sum of the percentage of very high, high and medium vulnerability classes register 72% of the total in area, 27% of which are very high class. This is due to the geological and hydrogeological permeable characteristics of the region, along with the geomorphological context of predominantly flat topography, which reduces the surface runoff in these plains and terraces, thus increasing the contact time of pollutants with the soil, favoring their infiltration. Intense urbanization and the absence of effective basic sanitation systems also contribute to increased vulnerability, exposing groundwater to a high risk of contamination by domestic sewage, solid waste, and industrial activities. The vulnerability map behaves as a tool to assist in the protection of groundwater resources against possible pollution. It can collaborate with future decisions related to water management, ensuring the long-term preservation of this vital resource for future generations.