MODELING GROUNDWATER FLOW AND SALINITY INTRUSION BY ADVECTIVE TRANSPORT IN THE REGIONAL UNCONFINED AQUIFER OF SOUTHWEST BANGLADESH

  • Sajal Kumar Adhikary Khulna University of Engineering & Technology, Khulna, Bangladesh
  • Prof. Ashim Das Gupta Asian Institute of Technology, Bangkok, Thailand
  • Mukand S. Babel Asian Institute of Technology, Bangkok, Thailand

Abstract

The southwest coastal region of Bangladesh is in a very complicated situation compared to its other parts due to direct interaction of the fresh groundwater with the saline surface water from coastal rivers and sea. A three-dimensional finite-difference groundwater flow model was employed to investigate the variety of hydrogeological conditions and to simulate the groundwater flow characteristics and dynamic flow exchanges between the rivers and underlying aquifers in the regional unconfined aquifer of southwestern Bangladesh. The MODFLOW modeling package in the framework of Groundwater Modeling System (GMS) was applied for this purpose. Stratigraphic modeling results of sub-surface lithology demonstrate that the upper unconfined aquifer of the region is extended up to a depth of 150m below the ground surface containing two distinct layers. Natural recharge from precipitation formed the main input to the aquifer system and abstraction from wells was the main output. The two-layer model was calibrated in two steps using observed groundwater levels: a steady-state calibration against 1992 data and a transient calibration and validation for 1992-2005 data. The simulation results show that the fluctuations of hydraulic heads are dependent on seasonal variation in recharge from precipitation. Advective transport of salinity was assessed by coupling the modeling package MT3DMS with MODFLOW in the framework of GMS. The model result reveals that the saline front lies close to the sea boundary and has very little effect on groundwater. Also, the dynamic interaction simulation depicts that the dynamic flow exchanges has a significant effect on the salinity movement from the salinity contaminated coastal rivers into the underlying aquifers. The result also reveals that salinity intrusion from coastal rivers, in the form of recharge water, is the predominant factor affecting groundwater system rather than the intrusion directly from the sea side.

Published
2011-08-01
How to Cite
KUMAR ADHIKARY, Sajal; ASHIM DAS GUPTA, Prof.; S. BABEL, Mukand. MODELING GROUNDWATER FLOW AND SALINITY INTRUSION BY ADVECTIVE TRANSPORT IN THE REGIONAL UNCONFINED AQUIFER OF SOUTHWEST BANGLADESH. EACEF - International Conference of Civil Engineering, [S.l.], v. 1, p. 037, aug. 2011. Available at: <http://proceeding.eacef.com/ojs/index.php/EACEF/article/view/349>. Date accessed: 19 may 2024.
Section
Group of Infrastructure Engineering