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Authors
Affiliations
1 Department of Geology, Dhaka University, Dhaka 1000, BD
2 Cairn Energy Companies in Bangladesh (CEEiB), BD
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 6 (2008), Pagination: 753-762
Abstract
The study area, located in the middle part of Chandpur district, Bangladesh, belongs to Meghna floodplain region. The shallow aquifer in the area is highly contaminated. Eight vertical electrical soundings using Schlumberger configuration with spreading of 800 m (AB/2 = 400 m) were conducted. The geophysical model exhibits three distinct ranges of resistivity zones: low (4.0 to 11.90 Ωm), moderate (13.0 to 58.0 Ωm) and variable (10.3 to 75.0 Ωm). Geological interpretation reflects anomalous resistivity for topsoil horizon, moderate resistivity for the fresh water bearing sandy materials and low resistivity for the saline water bearing sands or clay. Physico-chemical analysis of groundwater samples shows pH in the range of 6 to 9, EC values 1169 to 4330 μs/cm for the shallow aquifer (20 to 77 m), and 367 to 3820 μs/cm for deep aquifer (198 to 260 m); changing of water quality with depth and higher concentration of sodium and chloride in the shallow aquifer than in the deep aquifer. Hydrochemical facies analysis shows the water of shallow aquifer is NaCl type and that of deep aquifer Ca-Mg-HCO3 type.
Keywords
Geo-Electric, Resistivity Survey, Hydrogeology, Groundwater, Bangladesh.
