Hydrogeochemistry of granitic aquifers in southern Angola

The municipality of Caimbambo (Benguela) has a precarious drinking water supply system, making the use of groundwater an alternative for domestic supply in the region. This study was developed between February and July 2010 with the aim of characterizing the hydrogeochemistry of perforated crystalline aquifers. For this purpose, a field survey was carried out - observation and data collection in the social and technical scope; macroscopic classification of sediments; analysis of the results of bailer tests (4 boreholes) and hydrochemical and bacteriological tests (12 boreholes). The results of the bailer tests were positive for the supply of 25 l/person/day to a population of up to 250 inhabitants, the hydrochemical analyses revealed the relationship between the chemical composition of the waters - essentially calcic or magnesian bicarbonate - and the lithology of the said granitic aquifers and made it possible to verify the negative influence of poor environmental sanitation on the quality of the waters for human consumption, since the samples analysed were contaminated by at least one type of bacterium from human or animal faeces.