Electrical water detection

Jun 22, 2011

A quick and easy way to detect groundwater in semi-arid hard rock areas that is also economical could improve the siting of borewells to improve clean water supply in the developing world. Details of the approach are outlined in the International Journal of Hydrology Science and Technology this month.

P.D. Sreedevi, Dewashish Kumar and Shakeel Ahmed National Geophysical Research Institute in Hyderabad, India, explain how electrical conductivity (EC) logs of hard rock terrain recorded before and after the can reveal differences that show where water accumulates most in subterranean rock fissures. By comparing the data with other geological measurements and drilling experiments, the team is available to correlate the EC data with regions of underground water without additional test drilling.

Understanding hard rock aquifers relies on hydrology of fractured rock and knowing details of the subterranean environment. Data is commonly obtained through drilling test boreholes or investigating underground openings. Such work is hazardous and time consuming and does not necessarily reveal the most appropriate site to sink a water well. However, anomalies in electrical conductivity measurements of which many have been made in various regions might be useful in finding the most abundant sources of groundwater.

The researchers demonstrated how effective the approach might be in correlating information from 25 boreholes in the Maheshwaram watershed situated in the Ranga Reddy district of Andhra Pradesh, India, about 30 kilometers south of Hyderabad, covering an area of about 60 square kilometers. The area is semi-arid with average annual rainfall of 750 millimeters. The bedrock is mostly granite. The team points out that, based on the detailed geological and hydrogeological studies, the aquifer is classified as a two-tier coupled system with weathered and fractured layers that exist over almost the entire area. However, due to over-exploitation, the groundwater levels have affected the weathered layers and groundwater flow is currently in the fractured rock aquifer. There are no rivers feeding the aquifers so the system relies on the monsoon to for replenishment.

"Our approach is fast and cost effective and could be very useful as a screening tool prior to conducting hydraulic testing and sampling," the team concludes.

Explore further: NASA's HS3 mission spotlight: The HIRAD instrument

More information: "Vertical disparity in electrical conductivity of groundwater: inferring water-bearing fractures in granitic aquifer" in Int. J. Hydrology Science and Technology, 2011, 1, 105-124.

add to favorites email to friend print save as pdf

Related Stories

Satellite data explains vanishing India groundwater

Aug 12, 2009

(PhysOrg.com) -- Using satellite data, UC Irvine and NASA hydrologists have found that groundwater beneath northern India has been receding by as much as 1 foot per year over the past decade - and they believe ...

Groundwater depletion rate accelerating worldwide

Sep 23, 2010

In recent decades, the rate at which humans worldwide are pumping dry the vast underground stores of water that billions depend on has more than doubled, say scientists who have conducted an unusual, global ...

Recommended for you

Fires in Central Africa During July 2014

13 hours ago

Hundreds of fires covered central Africa in mid-July 2014, as the annual fire season continues across the region. Multiple red hotspots, which indicate areas of increased temperatures, are heavily sprinkled ...

NASA's HS3 mission spotlight: The HIRAD instrument

23 hours ago

The Hurricane Imaging Radiometer, known as HIRAD, will fly aboard one of two unmanned Global Hawk aircraft during NASA's Hurricane Severe Storm Sentinel or HS3 mission from Wallops beginning August 26 through ...

User comments : 0