Skip to main content

The Importance Of Geophysics In Groundwater Investigation



Before we delve into this, we need to first of all define some terms.

What is Geophysics?      It is the use of Physics to solve Geology problems.

What then is Geology?  Simply the study of the Earth. This includes the structure and the rocks.

Geophysics is usually employed when it involves probing the subsurface. In physical Geology, you are dealing with the surface geology, i.e. the structures, forms, and the lithofacies that are visible on the surface.

To solve environmental issues, mining, archeological, engineering (Geotechnical) and geological (hydrogeological) problems, geophysics is employed. It is achieved by passing an electric current via two current electrodes and the potential drop between the two current electrodes is measured by a voltmeter. From this, the resistance is deduced. Here, the current (I) is already known and the potential drop (V) is known as well.
Given the formula:          
V=I×R                                                                           ------- (1)
Making R the Subject:    R=V/I                                    ------- (2) {where R is measured in Ohms}

The essence of carrying out this is to determine the intrinsic properties of the geologic materials present in that environment. What the geophysicist is interested in per see is the Apparent Resistivity. This is usually affected by the presence minerals, groundwater, and porosity.


For groundwater investigation, Electrical Method is used. It involves the introduction of current via wires to the electrodes i.e. Vertical Electrical Sounding (VES). There are two main arrays for this: The Schlumberger array and Wenner array. Although each array has its own limitation, it will help you infer how the subsurface looks like.


There are however some factors that determine the accuracy of your results and are:

  1. The accuracy of the equipment (terrameter) used.
  2. The competency of the geophysicist.
BELOW IS A DISPLAY OF THE ASSEMBLAGE OF THE EQUIPMENT


Fig 1: ASSEMBLAGE OF THE EQUIPMENT(Terrameter) for Geophysical Investigation.


From the readings gotten and interpretation made, the rock-bearing-water is ascertained and the depth of penetration is known.

Comments

Post a Comment

COMMENT

Popular posts from this blog

Haystack rock of Cannon Beach, Oregon

credit: I just stumbled upon this rock called Haystack Rock located in the coast of Oregon. It is a popular icon and a tourist centre especially for movie makers. The sea-washed sand on Cannon Beach makes a mirror image of the 235-foot basalt monolith known as Haystack Rock. Further reading... It might interest you to know that at low tide, holes and crags in the stone’s base become tide pools, a primary habitat for numerous sea creatures. At the rock’s high tide level is the abode of the sea birds like bald eagle, tufted puffins, and pelagic cormorants. See Credit Here:
Post a Comment
Read more

THE AGE OF THE EARTH - THE OLDEST MAN ON EARTH IS THE EARTH

THE AGE OF THE EARTH Hey … Just as we celebrate our birthdays to commemorate the day we were born, has it ever occurred to you to ponder on the age of the earth? Don’t you think that there was a day (way back) when the earth was formed? Don’t get it twisted!!! This is no myth. It is a reality. It is REAL!!! The Earth is approximately 4.6 billion years old!!! Sounds absurd??? Well, this figure did not come as a result of fiction or imagination – but by radiometric dating in the early 20 th century. Lead in uranium-rich minerals when dated by early scientists,  were able to discover that they were billions of years old. Another pointer to this is that small crystals of Zircon obtained from Jack Hills, Western Australia when dated, was around 4.4 billion years old. One may ask: “How is this possible”? Rocks are aggregate of minerals. Some of these minerals have radioactive elements like Uranium and Thorium. In the process of their decay (radioac...
11 comments
Read more

GROUNDWATER POLLUTION (vis-à-vis Groundwater Quality) AND CAUSES

Groundwater in it’s natural state is made up of dissolved substances including gases. These contribute greatly to it’s quality. The surrounding environment (Formations), anthropological and bacterial activities influence it’s quality as well. Below is a rundown of factors that determine the quality of any groundwater: They can be categorised into: 1.    Physical factors; 2.    Bacterial factors; 3.    Chemical factors; 4.    Anthropological factors. Physical factors can be easily seen with the eyes without first being analysed in the laboratory. They are apparent to the physical senses of sight, smell, taste and in some cases, touch. It can be known physically if a groundwater is polluted or not by Colour changes, Odour, presence of suspended materials. The presence of suspended materials make the water appear cloudy. Commonsensically, no sane person will like to consume anything, let alone, water tha...
2 comments
Read more