Impact of high-strength wastewater infiltration on groundwater quality and drinking water supply: the case of Sana'a, Yemen

摘要: Abstract In Sana'a, the capital of Yemen Arab Republic, a major well inventory was compiled in 1995 during which samples were analysed for cations and anions. Five years later opportunity taken to repeat exercise on sub-set original wells. The results showed that groundwater urban area characterised by high concentrations almost all anions due continuous infiltration wastewater into aquifers via cesspits. dominant watertype appeared be CaCl2. Cl−-concentration ranged from 3 10 mmol/l NO3−-concentration 1 3 mmol/l while NH4+ absent samples. It is concluded cation exchange has place. Ca2+ been enriched, Na+, K+ have depleted. Groundwater affected had pH values 0.5–1 unit lower than not wastewater, indicating acidification Over period between two surveys, increased, decreased, both owing wastewater. An exploratory one-dimensional transport model 200 m column aquifer underlying Sana'a that, over 15-year infiltration, quarter present raw sewage would oxidise NO3− thereby producing acidity some 60% adsorbed. indicates after 50 become limited capacity (CEC) soil. Therefore more will oxidised [NO3−] rise. At same time, zone oxidation very acid lack buffering minerals. modelling studies, together with tend indicate up 12% current population city could dependent contaminated their drinking water supply.