Application of Electrical Resistivity Method for Groundwater Exploration in a Sedimentary Terrain. a Case Study of Ilara-remo, Southwestern Nigeria
A geophysical evaluation using Electrical Resistivity method for groundwater exploration at Ilara-Remo, southwestern Nigeria was carried out. The investigation involved the utilization of Vertical Electrical Sounding (VES) technique with schlumberger electrode array system. The studied area is located within the sedimentary basin (Dahomey basin) of southwestern Nigeria, ferrigenous sandstone was found to be the major rock type in the study area. The data acquired from the ten (10) VES stations were interpreted using the partial curve matching method and computer assisted iteration technique. The VES results of the data revealed three to five layers which include the topsoil, clayey/sandy clay, clayey sand, conglomeratic sandstones and sandstones/wet sands with resistivity values ranging from 133. The sanstones/ wet sands constitute the main aquifer units. From the overall results the studied area can be classified as prolific zones for groundwater development. INTRODUCTION The availability of quality water resources has always been the primary concern of societies in (Semi Arid and Arid region, even in areas of more abundant rainfall, the problem of obtaining an adequate supply of quality water is generally becoming more acute due to ever increasing population and industrialization.
Sub-Surface Investigation Using Vertical Electrical Sounding: Chennai Metropolitan Area
The data or information on the sub-stratum, nature of aquifers, their spatial disposition, their hydrogeological characteristics and other information, are limited particularly in urban context. The study was performed in the Chennai metropolitan area. The objective of the study was to get the sub-surface information of the study area. The vertical electrical sounding was performed at ninety locations to identify the sub surface lithology. The Archaeans consisting of Charnockites, gneisses and dolerite occupy the southern part of the Metropolitan area. The lower portion of gondwanas belonging to the Talchir beds consist of light brown and green colored Shales occurring below the alluvium in the area between Nandanam on the east to Nandambakkam on the west. These Shales are overlying the older crystalline rocks. The lower portion of gondwanas belonging to the Talchir beds consist of light brown and green coloured Shales occurring below the alluvium in the area between Nandanam on the east to Nandambakkam on the west The Tertiary bed comprising friable white and reddish brown Sandstone occurs on the western side near Chembarambakkam and on the northwestern side between Thirunindravur and Villiwakkam. The thickness of the alluvium ranges between 5m on the southern side to a little more than 20m on the east central part of the Metropolitan area.
Archaeological Survey of Dangoyama Kofun by 3DGPR
We presented a three-dimensional ground penetrating radar (3DGPR) system for the archeological investigation in a harsh site, where we have to deal with many trees and/or great topographic variations. This system consists of a commercial GPR system with a laser positioning system. With this system, we can move the GPR antenna freely, on which a positioning detector can record accurate position for each GPR data trace. We applied our 3DGPR system at Dangoyama Kofun, a burial mound, in Fukushima prefecture, Japan. A lot of trees and bushes covered the survey area and cannot be cut. We acquired six datasets in two days in this area. We successfully imaged the boundary between the original surface of the burial mound and the covering soil clearly at about 0.3 m depth around the mound. Furthermore, we found some strong reflections appeared at 0.8 m depth in the top area of the mound, which can be from the artificial parts of the burial mound. The results would greatly aid the following archaeological excavation. In addition, we compared the non-interpolated depth slice with interpolated depth slice at same position and demonstrated that the interpolation process on threedimensional GPR data may introduce some artifacts which might mislead our interpretation.