vulnerability in santiago Island - Cape Verde

• Autor(a) principal: Antonio Pedro Said Aly de Pina
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFC
• Texto Completo: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13138
• topic: QUALIDADE; VULNERABILIDADE; POLUIÃÃO HÃDRICA; DRASTIC; QUALITY; VULNERABILITY; WATER; POLLUTION; DRASTIC.; GEOLOGIA

Groundwater is an essential natural resource for life and the integrity of ecosystems that are dependent on them. Santiago Island - Cape Verde has 991 km2, representing about 30% of the total area of the archipelago, where many ecosystems are threatened by over-exploitation of groundwater by human and diffuse pollution, salinization of aquifers and affecting the direct and indirect climate change impacts on water availability, all demanding urgent solutions and adequate knowledge of the characteristics of the physical environment. The research aims to evaluate groundwater and the degree of aquifer vulnerability to contaminations of various hydrogeological formations and fundamentally arises from the need to provide a tool that is useful in decision-making to define strategic areas of protection and groundwater recharge level. The use of multidisciplinary methodology, such as chemical analysis, isotopic analysis, the calculation method of recharging the water balance of Thornwaite as a function of altitude and the mapping of aquifer vulnerability using the DRASTIC index, were used to characterize the quality of groundwater identify human actions and show differences in chemical compositions between hydrogeological units. The results of these studies are embodied in technical summaries with information, diagnoses, and proposals were interpreted/handled by PIPER diagrams, maps hydro chemical zoning of key major ions, factorial components analysis and mapping of vulnerability DRASTIC. The values obtained show that the DRASTIC indices vary between 65 and 208. These indices show that there are hydrogeological situations corresponding to a very high vulnerability to scale 1: 220.000. Natural recharge of the aquifer occurs only in areas of higher altitude (> 600 m) considered semi-humid zones and taking maximum rainfall of 129,6 mm / year. The average annual rainfall during the 47 years of record rainfall is 306,3 mm/year with inhomogeneous spatial variability within a short time period (August-October) with potential evapotranspiration of 1628,30 mm / year and mean annual temperature of 26.5 Â C.