Low-Cost Resistivity Meter for Groundwater Exploration Using High Voltage Experimentations

Abstract

Resistivity survey is very well known for the exploration of groundwater and to determine the depth of bedrock. Generally, in Pakistan local drillers rarely use resistivity meter due to high cost of commercially available equipment. Therefore, most of the wells for groundwater are drilled without any feasibility survey, which causes economic and time loss. An inexpensive resistivity meter has been developed that can help the local community to conduct a survey for groundwater. This designed equipment is handy, portable, easy to operate and can be manufactured locally. This equipment costs 500 US Dollars (USD), whereas commercially available equipment costs 2500 to 50000 USD. The designed portable device comprises of a 12V DC battery, an inverter, multiplier circuit, DPDT switch and electrodes. A 12V DC battery is fed to an inverter to achieve AC supply of 220V. The achieved AC voltage is rectified to DC-voltage which is further enhanced up-to 1300 volts using voltage multiplier circuit. This high DC voltage is called High Voltage Direct Current (HVDC). HVDC is switched at very low frequency of 1Hz. Automatic switching is being accomplished by means of DPDT relay and its control circuitry. HVDC at low frequency is applied to the earth through electrodes to determine resistivity for different materials lying inside the ground with a penetration depth of 100 meters. This portable instrument would be useful to map surface lithological layers, determine quality of groundwater and bedrock level in accurate and inexpensive way

Keywords

• groundwater geophysics and structure
• inexpensive
• resistivity
• high voltage direct current
• low frequency.