Traçage de la recharge des aquifères situés sous une mégapole asiatique à l’aide de Cl/Br et des isotopes stables: exemple de Dacca, Bengladesh Seguimiento de la recarga en acuíferos por debajo de una megaciudad asiática con Cl/Br e isotopes estables: el ejemplo de Dhaka, Bangladesh ক্লোরাইড/ব্রোমাইড অনুপাত ও স্থিতিশীল আইসোটোপ ব্যবহার করে এশিয়ার একটি মেগাসিটির তলদেশের একুইফারগুলোতে ভূগর্ভস্থ পানির রিচার্জ পথের অনুসন্ধানঃ বাংলাদেশের ঢাকা শহরের উদাহরণ 采用Cl/Br和稳定同位素示踪剂追溯亚洲特大城市之下含水层的补给:孟加拉达卡研究实例 Ras

• Published in: Hydrogeology journal Vol. 22; no. 7; pp. 1549 - 1560
• Main Authors: Hoque, M. A, McArthur, J. M, Sikdar, P. K, Ball, J. D, Molla, T. N
• Format: Journal Article
• Language: English
• Published: Springer-Verlag 2014
• Subjects: aquifers; arsenic; barium; bromine; cadmium; copper; drinking water; electrical conductivity; groundwater; lead; nickel; rivers; salinity; sanitation; selenium; stable isotopes; surface water; water supply; wells; Bangladesh
• ISSN: 1431-2174; 1435-0157

Dhaka, the capital of Bangladesh, is home to a population of 15 million people, whose water supply is 85% drawn from groundwater in aquifers that underlie the city. Values of Cl/Br >500 are common in groundwater beneath western Dhaka in areas <3 km from the river, and in rivers and sewers around and within the city. The study shows that groundwater beneath western Dhaka is strongly influenced by infiltration of effluent from leaking sewers and unsewered sanitation, and by river-bank infiltration from the Turag-Buriganga river system which bounds the western limit of the city. River-bank infiltration from other rivers around Dhaka is minor. Values of Cl/Br and Cl concentrations reveal that 23 % of wells sampled in Dhaka are influenced by saline connate water in amounts up to 1%. This residual natural salinity compromises the use of electrical conductivity of groundwater as a method for defining pathways of recharge by contaminated surface waters. Concentrations of As, B, Ba, Cd, Cu, F, Ni, NO₃, Pb, Sb, Se and U in groundwater samples are less than WHO health-based guideline values for drinking water.