Groundwater Exploration Techniques

The demand for groundwater for drinking water and other requirements is increasing day by day because of the tremendous rise in the worldwide population. Firstly understand, what is groundwater? The groundwater is a natural renewable water resource obtained from beneath the earth surface, which gets replenished after every rainfall. However, this renewable resource is getting depleted due to its significant exploitation worldwide. Over time, the groundwater has gone deep below the surface. Various techniques equipped with advanced technologies for groundwater exploration are further discussed in this blog.

Groundwater distribution

Groundwater is one of the precious resources that are most widely distributed within the earth, subsurface within sediments, rocks, ice, and snow. As per the studies, around 5.97 quintillion gallons of groundwater reside in the upper 2 km of the earth’s surface. Groundwater is heterogeneously distributed everywhere. The groundwater occurrence, its flow, and storage properties are determined by the geological structure, geomorphology and rainfall pattern.

Groundwater Exploration 

The groundwater is widely distributed everywhere, finding the accurate position of the water becomes quite a challenging job. The occurrence and distribution of groundwater resources are confined to certain geological formations and structures. Various groundwater exploration techniques come into the picture. Prospecting groundwater requires a detailed study of the concerned area with a geographical investigation and analysis. The groundwater exploration techniques are classified into Arial, Surface, and Sub-Surface that have been improved from traditional methods to the high technology-based techniques.

Aerial Method

Aerial exploration is the most convenient method for locating watersheds of basins within large areas. The aerial photos are captured through remote sensing techniques, which obtain credible information about the earth’s surface without any physical contact. These photos are captured in black & white colour. This process is found to be very effective in identifying the geomorphic units, structures like faults, joints, fractures, folds, and drainage because they play a crucial role in controlling the movement and occurrence of groundwater.

Some of the advantages of the Aerial Method are:

• Cost-friendly
• Time-saving study
• Provide more ground surface information compared to topographic maps
• This study is easy to carry out

Surface Methods 

It is the most common, time-saving, and easy-to-operate method for groundwater exploration. The surface methods of groundwater exploration consist of different techniques such as esoteric, geology, geomorphology, geophysics, hydrogeology, soil & Microbiological Methods, etc.

• Esoteric Method: 

This is the oldest groundwater exploring technique, also known as the water-dowsing or water-divining method. This is not a scientifically proven method, but the traditional people believed the flow of groundwater can induce current above the ground surface. Wet twigs of trees, husk-free coconuts, and other similar materials were used as divining materials in this method.

• Geological Method:

The geological method is based on the principle that groundwater occurrence and movement directly depend on the area’s geology. The geological study begins with collecting and analysing aerial photographs, topographic maps, and other vital records. It is most pertinent to undertake a depth study on the type of terrain, lithological units, and geological structures such as lineament, fold, joints, and fracture systems for groundwater exploration.

• Geomorphological Method:

This method is essential to ascertain the potential to access the groundwater. Streams and watercourses are controlled by varying landforms, originating due to geological processes. River-borne modern alluvial terraces, floodplains, Moraine deposits, glacial outwash are some of the positive landforms for groundwater. Geomorphic units such as flood plains, soil types, lineaments are the factors that control the occurrence of groundwater. 

• Hydrogeological Method:

The hydrological setup of an area is also a factor in creating groundwater potential. This method helps to evaluate the potential of groundwater for a given area/basin. In the absence of this investigation, the evaluation of groundwater potential tends to be stuck only in the geophysical study. 

• Soil & Microbiological Methods

Studies have proven that the lush green forests and other botanic indicators are valuable tools in groundwater exploration. The growth of crops, vegetation, forests with big trees, location of aged, deep-rooted trees can help indicate groundwater occurrence at shallow depth. Various characteristics & nature of some plants help find out the location & types of groundwater.

Sub-surface Method

This groundwater exploration method includes Test Drilling & Borehole Geophysical Logging techniques. Test drilling is an easy and direct method to reach the groundwater source. However, it is not feasible for every individual due to the high cost. That is why these sub-surface methods are comparatively more expensive than the surface methods. 

Some of the other groundwater exploration techniques are as under:

• Gravity Method

The measurement of the gravitational field at different locations helps in exploring groundwater along with oil & gas. The objective of this method is to measure the differences in the distinguished densities and rock types. The gravity method is also used to explore heavy minerals such as barite & chromite. 

• Seismic Method

The seismic method is developed from the science of earthquakes called Seismology. This method is used in two different kinds, seismic refraction and seismic reflection. The seismic refraction method creates a small shock on the earth’s surface and measures the time of returning sound from the surface. The seismic reflection is also based on the same principle. However, it provides information for thousands of meters below the surface. In contrast, the refraction method is used to conduct the study only 100 meters deep below the surface.

Conclusion 

The occurrence and movement of groundwater are subjected to various factors such as its geology, hydrology, land planes, etc. Thus, it requires carrying out different types of studies to identify the potential zones of groundwater. The modern tools and techniques are helpful in groundwater exploration to satisfy the need for drinking water and other human requirements.