Aquifer demarcation and groundwater resources assessment in lohagara municipality, narail, bangladesh

01 September 2012; Accepted 18 October 2012 This study presents the state-of-the-art methodology for investigating existing hydrogeological framework for delineating underlying aquifer system and existing groundwater (GW) resource assessment in Lohagara Municipality of Narail district in Bangladesh. Numerous hydrogeological, lithological, hydrological, meteorological and other relevant data and information in the study area have been collected. A number of hydrostratigraphic columnar sections representing the extent of aquifer system have been produced and yield properties of sediment formations are determined. The striplog distributions reveal that a productive aquifer exits beneath the study area with the alteration of fine sand aquifer, aquitard and aquiclude layers. The analysis also demonstrates that two major (upper and lower) aquifers are present within the depth from 61 m to 95 m and from 198 m to 216 m or beneath the study area. It is found that a prominent aquifer exists at 200 m to 235 m throughout the study area containing varying thickness of more or less 36 m below the aquiclude. However, estimated specific yield of aquifer materials varies from 0.07 to 0.20 indicating that the aquifer consists of fine to medium sand. The analysis of storage coefficient and hydrostratigraphic sections shows that the upper aquifer is semi-confined and lower aquifer is confined in nature. Based on the GW modelling results by an integrated MIKE-11 and MIKE-SHE platform, the study estimates that GW resources for shallow aquifer on May 01, 2003 for 6 m and 7 m depths are 7.48 million cubic meters (MCM) and 10.00 MCM, respectively, whereas on November 01, 2003, the resource is estimated as 11.29 MCM and 13.81 MCM for 6 m and 7 m depths, respectively. According to water balance studies, the GW recharge is found as 390 mm for the deeper aquifer in 2003 and the corresponding annual aquifer storage volume is estimated as 7.25 MCM, which mostly comes from the horizontal flow. Based on long-term simulation of GW model using potential water withdrawal options in future, the study concludes that the aquifer is sustainable for GW use in Lohagara Municipality of Narail district in Bangladesh.