Groundwater is an important natural source of water supply throughout the world. It is precious and most widely distributed resource. The use of groundwater is increasing day by day in irrigation, domestic water supply, municipalities, rural areas, and industries. It gets its replenishment from precipitation, surface flow and reserves. Now a day’s large scale abstraction results in lowering of groundwater level is a serious threat to future groundwater irrigation development. Bangladesh is no more exception to the deteriorating condition of the water resources systems. So, a detailed study is needed to identify the subsurface formations. One of the most important aspects for groundwater investigation program is the knowledge about the underlying formations. It gives a clear picture of the information needed, such as, the probable aquifer, its location, thickness, composition, etc. In this research, the lithological borehole data of 467 locations have been collected, compiled, processed, analyzed and interpreted for studying the hydro- geological properties of 18 upazillas of the study area. Borehole log is one such method that furnishes information on substrata in vertical line from the surface. These furnish a description of the geologic character and thickness of each stratum encountered as a function of depth, thereby enabling aquifers to be determined. Shaded contour maps of clay, fine sand and composite sand thickness have been presented for qualitative study of groundwater potentiality of the area. Yield potential index map of the water saturated zone selects the suitable potential zone and hence identifies the proper location of well-sites. Stratigraphic and cross-sectional views in various orientations are prepared to visualize the subsurface of the study area. Stratigraphy influences the formation and distribution of groundwater. It studies the surface feature of the area and plays an important role in selecting the well sites. The availability and abundance of groundwater at different places are influenced by the stratigraphic feature.

Keywords : Stratigraphy; Uncofined Layer; Fence Diaram; Groundwater Exploration; Abstraction.