Sara Ghalamkari - Department of Geology, Fars - Tehran Science and Research Branch, Islamic Azad University, Fars, Iran
Abdolmajid Asadi - Department of Geology, Shiraz Branch, Islamic Azad University, Shiraz, Iran
Mohsen Pourkermani - Department of Geology, North Tehran Branch, Islamic Azad University, Tehran, Iran

Geoelectric is one of the geophysical field operations, which designed based on the transmission of electrical current into the ground, creating a potential difference between two points and calculating specific resistance of the ground in different depths. In this method, exploratory studies carried out based on the standards for the resistance of different soil and rocks, as well as the electrical resistance values of materials such as water, metals, cavities, etc. In addition, the maximum depth of identification is 500 meters, which up to a depth of 250 meters, gives a higher accuracy.The most important objectives of geoelectric operations are: 1-Exploration of groundwater aquifers for the construction of a new water well. 2- Identify the direction of groundwater. 3- Identification of geological structures such as faults (dip and strike), folds, discontinuities, etc. 4- Determine the location of old aqueduct (Quant). 5- Exploration of various mineral and nonmetallic mineral resources such as salt rock, clay, and barite and... .6- Determine the porosity of the subsurface rock and the level of settling. 7- Determine the location of the karst caves and underground cavities. 8 -Identification of contaminated areas, including oil pollution and underground gas resulting from the bursting of gas and oil pipelines. 9 -Identifying fractures created on the body of both soil and concrete dams, which can be the place of passing water. This study has done due to reduction of water leveling based on drought and excessive water extraction from aquifers, to determine the vulnerability and to investigate the environmental risks of Roniz aquifer to extract water management. The result shown that, the thickness of the unconsolidated overburden varies from 2.9m to 22.8m, where about 58% falls within the 10m-14.9m brackets. This shows that unconsolidated materials are thin and hence averagely low groundwater prospect. 73% of the topmost geoelectric layer in the study area has resistivity mostly within the range of 1-100 Ωm. Resistivity values within this geological formation to indicate silt, marl or clay sequence, which can constitute effective protective geologic barriers for the underlying aquifers. This suggests impervious/semi pervious materials (include silt, clay, marl or even mass limestone whit out any fractured) has geologically protecting the underlying aquifers from near-surface contaminants, so mostly cap aquifers within the unconsolidated overburden at Roniz

Geo-electric, resistivity, Vertical Electrical Sounding, Aquifer, Roniz plain