Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

Chowdhury S. Jahan ¹, M. D. Aminul Islam ¹, Quamrul H . Mazumder ¹, M. D. Asaduzzaman ², M. D. Moynul Islam ¹, M. D. Ohidul Islam ¹, Akia Sultana ¹

Affiliations
1 Department of Geology and Mining, University of Rajshahi, BD
2 Bannd Multipurpose Development Authonty, Rajshahi, BD

Abstract

The depositional environment and aquifer condition of the Barind area of Bangladesh were studied using gamma ray log data. Attempts were made to evaluate the aquifer potentiality, either single or Multi-Layer considering thickness, depth of occurrence and viability of exploitation Study indicates that sedimentation occurred in floodplain to point or channel bar environment. In the sandy layer in the western part of the study area less matured coarser sediments were transported from shorter distance. The area is covered by 3 0-47 5 m thick Semi-Impervious Clay-Silt layer of Pleistocene to recent age and is characterized mostly by single aquifer within the depth range of 9 0-51 5 m below ground level. But in the eastern, southeastern, southern, northeastern and northern parts aquifer system of Pho-Pleistocene age. IS multiple layered (two-four) with thickness of 5 0-42 5 in at different depth levels. In the northern and southern parts of the Central Barind Tract and the Atrai valley potential aquifers occur at different depths shallow (up to 30 0 m from GL) and intermediate (30 0-50 0 m from GL), and deep (> 50 0 m from GL). The southeastern part of the Tract IS more potential for deeper aquifers than other parts Usually, the average discharge of a well in the area is 2 cusec (56 6 Ips) but as result of innovated and cost effective drilhng and construction DTWs produce desired discharge of 3 cusecs (84 9 Ips) with reasonable specific drawdown, increased specific yield and better well performance (with 2 9 times more specific capacity) Central part of the area with T<500 m²/day refer to as suitable for development of water supply and pump use, but the rest the area with T=500->1000 m²/day indicate good development potentiality for irrigation and water supply.

Keywords

Depositional Environment, Gamma Ray Log, Aquifer, Barind, Bangladesh.

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Rumy Afroza ¹, Quamrul H. Mazumder ¹, Chowdhury S. Jahan ¹, M. A. I. Kazi ², M. A. Ahsan ², M. A. Al-Mansur ²

Affiliations
1 Department of Geology and Mining, University of Rajshahi, Rajshahi, BD
2 Analytical Research Division, Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Dhaka, BD

Abstract

Hydrochemistry in parts of the Lower Tista Floodplain in northwest Bangladesh is dominated by alkalies and weakly acid, having highest concentration of sodium cations and bicarbonate anions respectively. Groundwater is characterized by sodium-calcium and sodium-potassium cation and bicarbonate-chloride-sulphate anion facies, and genetically 'normal chloride', 'normal sulphate', and 'normal carbonated' type, and soft to saline. Based on electrical conductivity values, the area is divided into northern fresh and southern saline groundwater zone, and values like salinity, Na%, SAR, and RSC and a good correlation between Na⁺ and Cl^-, and Cl^- and salinity reveals increasing salinity with depth indicating a mixing of fresh and saline bodies due to marine transgression (?) during Holocene period in the Bengal delta. The rock weathering is likely to affect the groundwater quality by dolomite dissolution and calcium precipitation, representing reverse softening process and is brine seawater. Water extracted from shallow zone (from 20 to 30 m) has suitability for drinking purpose, livestock consumption and irrigation purposes, and partially suitable for industrial use, but that from deeper zone (from 30 to 50 m) is generally poor and unsuitable especially for irrigation purposes with low alkali and moderate to high salinity hazard. So groundwater can be used for irrigation in the area of fine textured soil with proper management practices.

Keywords

Hydrochemistry, Salinity, Tista Floodplain, Bangladesh.

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