Composite Geoelectrical Investigation to Delineate Groundwater Feasibility in Hard Rock area of Raipur, Chhattisgarh, India.

In hard rock terrains, groundwater movement, migration, and storage occur through subsurface fractures. To assess the fractures and associated water, we carried integrated geophysical investigation with Wenner, (GRP), Schlumberger, and Pole-Dipole array in Indian State. The resistivity survey carried out using a CRM-500 resistivity meter. The analyzed results are also re-verified with the help of IPI2WIN software. Initially, lateral and surface variations of resistivity were plotted by using Wenner and Gradient Resistivity profiling array. Then the low resistivity points were investigated with Schlumberger and Pole-Dipole array. In interpretation, low resistive zones identified correspond to the possible fractured zones. The results allowed mapping of the weathering zone at depth 12 to 15 m, and deep fracture lies below depth 55.0 m depth. The present study validates that the integrated Geophysical survey is a powerful exploration technique to scrutinize and identify water-bearing fractures in the hard rock area.

A NEW BRANCH OF THE ANIO NOVUS AQUEDUCT (ROME, ITALY) REVEALED BY ARCHAEOLOGY AND GEOPHYSICS

The area south-east of Rome is characterised by the presence of several roman aqueducts which brought water to the eternal city from the Apennine and Alban Hills springs. In the last 40 years, several pieces of evidence about these aqueducts were acquired during the realisation of archaeological test trenches before building activities. In 2019, a small branch of a subterranean aqueduct unknown to the Latin sources was unearthed in Via dei Sette Metri. Here we show that this aqueduct is a lateral branch of the Anio Novus, a major imperial aqueduct built between 38 and 52 CE. To achieve this result, we employed detailed photogrammetric restitution of the new aqueduct and an integrated geophysical survey focused in the area where the Anio Novus was supposed to pass. Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) methods were used to reconstruct aqueduct paths and their relative heights. Different light conditions were tested during the picture acquisition step to determine the best practice in the photogrammetric restitution. The results obtained in this study confirmed the great effectiveness of the integration between geophysical investigation methods and the modern archaeology approach in detecting buried ancient structures.

Mapping of groundwater potential using integrated geophysical techniques at forestry research institute of Nigeria, Ibadan, South Western Nigeria

Water is an essential commodity for life survival on Earth. Groundwater exists below the surface in the soil pores, fractures within rocks, fissures, and other weak geological features or zones. The aim of this research was to delineate groundwater potential within the Forest Research Institute of Nigeria (FRIN) and hence determining the possible areas suitable for siting borehole for sustainable potable water supply. Four electromagnetic traverses were carried out and ten vertical electrical sounding (VES) points were identified for detailed probing using the Schlumberger configuration. Wenner array survey was also carried out along two traverses. The VES data collected was processed using curve matching and Computer software called Winresist while Wenner array was processed using RES2DINV. The results from the interpretation of the four (4) EM profiles revealed low conductivity zone with a value ranging from 4.6 to 19.7 mS m.-1 The results of VES give a maximum of four subsurface geoelectrical layers with five curve types, which are K, Q, AK, HK, and KH. The weathered basement has a resistivity value ranging from143.8 to 450 Ωm and depth to basement ranging between 13.9 m and 39.4 m. The interpretation of the ten VES points obtained suggested that three VES points (VES 2, 5, and 7) are suitable for borehole drilling. The results of the 2D resistivity value ranges from 17.5 to 747 Ωm with a varying depth between 3.25 and 15.9 m. The results of the integrated geophysical survey techniques have proven to be an effective method for groundwater delineation in the study area. Keywords: Aquifer, Borehole, Electromagnetic, Geoelectric, and Groundwater

Applications of Aeromagnetic and Electrical Resistivity Data for Mapping Spatial Distribution of Groundwater Potentials of Dutse, Jigawa State, Nigeria

Optimal mapping of groundwater resource is usually accomplished using integrated geophysical survey in which two or more techniques are applied. In this work, spectral analysis of aeromagnetic data was used to map the topography of the magnetic crystalline fresh basement underlying the water bearing aquifer of Dutse, Jigawa State Nigeria. Vertical electric sounding technique was used to detect the spatial distribution of the depths to the top of the aquifer within the same area.  The overall goal of the work is to determine the groundwater potential of the area by mapping the spatial distribution of groundwater availability based on aquifer thickness and basement topography. The aquifer depth was found to be within the range of 5 to 15 m with a mean value of 10 m. The basement was found to be highly undulating having depths ranging from 6 to 69 m with a mean value of 24 m. The existence of isolated deep depressions within the basement which appears to be filled by water bearing sediments was thought to be favorable structures for groundwater accumulation. The spatial distribution of groundwater potential was therefore mapped in a reclassified image of three zones, high, moderate and low. The study therefore provides a vital tool for groundwater exploitation and management strategies.