Ratan Kumar Majumder, Jun Shimada, and Makoto Taniguchi

pp. 99 - 106

Abstract

Borehole temperatures were measured in observation wells to determine the temperature-depth profile, magnitude of
temperature and thermal gradient. The observed temperature profiles are classified into recharge and discharge types. The
recharge-type wells are located in the northern site of the study area. Meanwhile, discharge-type wells are found in the
southern site of the study area. The 2-D cross-section of subsurface temperature shows that the shallow groundwater temperature in the southern discharge area is higher than that of the northern recharge area. The calculated temperature-depth
profiles for shallow wells show the recharge rate ranging from 0.04 to 1.35 m/year and discharge rate within the range of -0.2
to -0.79 m/year. On the contrary, the recharge rate is 0.05 to 0.16 m/year and discharge rate -0.15 m/year for the deep well sites.
The present study has revealed the existence of shallow and deep groundwater flow systems in Bengal Delta aquifers.