Geological Investigations

Geological investigation is the most important method in groundwater exploration. It includes a brief study of a given area from different angles to predict the extent of groundwater occurrence in that region. Geological investigations also involve the study of the following.

Rock Types

The study of rock types refers to the occurrence of outcrops of rock types and their thickness, attitude, porosity, and permeability features. The attitude (i.e., dip direction) of bidding planes affects the groundwater movement below the area.

Topography

Topographic study relates to the existence of highlands(hills) and lowlands(valleys). The water table is parallel to the surface as it occurs at a higher level in hilly regions and in lowlands, it occurs at a depth below valleys. But the rise or fall of the water table is always moderate. Moreover, the flow of groundwater moves from places with a higher water table to a lower water table. In an exploration of groundwater, places of the lowest elevation are because the depth of actual occurrence of the water table is less when compared to the depth of the water table in hilly areas and the groundwater comes nearer to that point from various sides.

Weathering

• They have weathered zones
• Joints and fractures which may exist on the surface become less important and disappear at depth, the reason the porosity will be less, and therefore there is no scope for the existence of plenty of groundwater.
• The valleys and low-lying places, on the other hand, are appropriate for tapping groundwater because they are the places of natural accumulation of sediments. They are also the places where the occurrence of in-situ rock weathering is more common.

Geological, Geophysical, and Hydrological investigations are used to estimate the physical characteristics of the subsurface by measuring, analyzing, and interpreting seismic, electromagnetic, gravitational, and magnetic fields estimated at the ground surface.

Following are the different methods that are used for groundwater exploration.

1. Geological Investigations
2. Geophysical Investigations
3. Hydrological Investigations