MODULE 3
Hydrogeology –
Occurrence of groundwater, aquifers and types of aquifers, confining beds, porosity and vertical
distribution of groundwater. Darcy's Law. Permeability/hydraulic conductivity. Problems
created by groundwater to civil engineering structures, Methods to control groundwater
problems, Electrical resistivity survey for groundwater exploration. Seawater intrusion in coastal
area. Ghyben Herzberg relation.
HYDROGEOLOGY
• The study of the distribution and movement of groundwater in the soil and rocks of the Earth's crust
(commonly in aquifers) is hydrogeology, also called GROUNDWATER HYDROLOGY
• Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and
operating extraction wells
• Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water
• Groundwater (or ground water) is the water present beneath Earth's surface in soil pore spaces and in the
fractures of rock formations.
• A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of
water.
• The depth at which soil pore spaces or fractures and voids in rock become completely saturated with
water is called the water table.
OCCURRENCE OF GROUNDWATER
Groundwater is one of the most important natural resources. There are three sources of groundwater:
1. Meteoric water
2. Connate water
3. Juvenile water (Magmatic water)
1. Meteoric water
• It is the water derived from precipitation (rain and snow).
• It is a reliable source of water.
• It is dependent on duration of rain, porosity of ground and nature of ground during rain.
• These factors affect movement of surface water till groundwater table.
• The process of infiltration starts immediately after a rainfall. This infiltrating water continues its
downward journey to the zone of saturation to become a part of the groundwater in aquifers.
2. Connate Water
• It is the water that were trapped in the pores of sedimentary rocks as they were deposited.
1
, • When the sedimentary rocks form in lake, sea or river, deposition is followed by compaction,
which squeezes out water between the sediments
• However, incomplete compaction causes retention of water by these rocks
• Commonly saline in nature
• Of no importance as a source of exploitable groundwater
3. Juvenile water (Magmatic water)
• Magmatic water or juvenile water is water that exists within a magma or water-rich
volatile fluids that are derived from a magma.
• Hot molten masses or magmas existing below the earth‘s surface emit steam, which
condenses to form water, which occupies the cracks and pores of rocks. This water is
called Juvenile water (Magmatic water).
• This magmatic water is released to the atmosphere during a volcanic eruption Some
hot springs and geysers are derived from magmatic water.
A hot spring is a spring produced by the emergence of geothermally heated groundwater
that rises from the Earth's crust.
A geyser is a vent in Earth's surface that periodically ejects a column of hot water and
steam.
HYDROLOGICAL CYCLE
• Hydrologic cycle, describes the continuous movement of water on, above and below the
surface of the Earth
• It is merely a chain of events involving water as it exists in all its forms on or within the
Earth.
2
, • It is a continuous process.
• As a part of the hydrological cycle, the liquid (and solid) water evaporates from the surface
water bodies and is lost from the vegetation by transpiration. Under suitable conditions,
water vapour condenses into clouds and subsequently get precipitated in the form of rain,
snow, hail etc.
• For proper understanding of groundwater in all its aspects, the concept of hydrological cycle
must be understood clearly.
ZONAL DISTRIBUTION OF SUBSURFACE WATER
• The water that goes below the surface of land may be found to exist in two main zones, vadose
water and phreatic water (ground water).
• The vadose zone ("vadose" is from the Latin for "shallow"), also termed the unsaturated zone, is the
part of Earth between the land surface and the top of the phreatic zone, the position at which the
groundwater is at atmospheric pressure.
• The vadose zone extends from the top of the ground surface to the water table.
• Water in the vadose zone has a pressure head less than atmospheric pressure, and is retained by a
combination of adhesion and capillary action
3
Hydrogeology –
Occurrence of groundwater, aquifers and types of aquifers, confining beds, porosity and vertical
distribution of groundwater. Darcy's Law. Permeability/hydraulic conductivity. Problems
created by groundwater to civil engineering structures, Methods to control groundwater
problems, Electrical resistivity survey for groundwater exploration. Seawater intrusion in coastal
area. Ghyben Herzberg relation.
HYDROGEOLOGY
• The study of the distribution and movement of groundwater in the soil and rocks of the Earth's crust
(commonly in aquifers) is hydrogeology, also called GROUNDWATER HYDROLOGY
• Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and
operating extraction wells
• Groundwater is often cheaper, more convenient and less vulnerable to pollution than surface water
• Groundwater (or ground water) is the water present beneath Earth's surface in soil pore spaces and in the
fractures of rock formations.
• A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of
water.
• The depth at which soil pore spaces or fractures and voids in rock become completely saturated with
water is called the water table.
OCCURRENCE OF GROUNDWATER
Groundwater is one of the most important natural resources. There are three sources of groundwater:
1. Meteoric water
2. Connate water
3. Juvenile water (Magmatic water)
1. Meteoric water
• It is the water derived from precipitation (rain and snow).
• It is a reliable source of water.
• It is dependent on duration of rain, porosity of ground and nature of ground during rain.
• These factors affect movement of surface water till groundwater table.
• The process of infiltration starts immediately after a rainfall. This infiltrating water continues its
downward journey to the zone of saturation to become a part of the groundwater in aquifers.
2. Connate Water
• It is the water that were trapped in the pores of sedimentary rocks as they were deposited.
1
, • When the sedimentary rocks form in lake, sea or river, deposition is followed by compaction,
which squeezes out water between the sediments
• However, incomplete compaction causes retention of water by these rocks
• Commonly saline in nature
• Of no importance as a source of exploitable groundwater
3. Juvenile water (Magmatic water)
• Magmatic water or juvenile water is water that exists within a magma or water-rich
volatile fluids that are derived from a magma.
• Hot molten masses or magmas existing below the earth‘s surface emit steam, which
condenses to form water, which occupies the cracks and pores of rocks. This water is
called Juvenile water (Magmatic water).
• This magmatic water is released to the atmosphere during a volcanic eruption Some
hot springs and geysers are derived from magmatic water.
A hot spring is a spring produced by the emergence of geothermally heated groundwater
that rises from the Earth's crust.
A geyser is a vent in Earth's surface that periodically ejects a column of hot water and
steam.
HYDROLOGICAL CYCLE
• Hydrologic cycle, describes the continuous movement of water on, above and below the
surface of the Earth
• It is merely a chain of events involving water as it exists in all its forms on or within the
Earth.
2
, • It is a continuous process.
• As a part of the hydrological cycle, the liquid (and solid) water evaporates from the surface
water bodies and is lost from the vegetation by transpiration. Under suitable conditions,
water vapour condenses into clouds and subsequently get precipitated in the form of rain,
snow, hail etc.
• For proper understanding of groundwater in all its aspects, the concept of hydrological cycle
must be understood clearly.
ZONAL DISTRIBUTION OF SUBSURFACE WATER
• The water that goes below the surface of land may be found to exist in two main zones, vadose
water and phreatic water (ground water).
• The vadose zone ("vadose" is from the Latin for "shallow"), also termed the unsaturated zone, is the
part of Earth between the land surface and the top of the phreatic zone, the position at which the
groundwater is at atmospheric pressure.
• The vadose zone extends from the top of the ground surface to the water table.
• Water in the vadose zone has a pressure head less than atmospheric pressure, and is retained by a
combination of adhesion and capillary action
3
