DEPARTMENT OF CIVIL ENGINEERING

SHREE SA’D VIDYA MANDAL INSTITUTE OF TECHNOLOGY

SUBJECT:-GEOTECHNICS & APPLIED GEOLOGY

Topic:-Hydrology Cycle and Ground Water Occurrences

PRESENTED BY:- Name Enrollment

no. Dhaval Chavda

130454106001

Fahim Patel 140453106005

Navazhushen Patel 140453106008

WHAT IS THE HYDROLOGICAL CYCLE ? The hydrological cycle is the system

which describes the distribution and movement of water between the earth and its atmosphere. The model involves the continual circulation of water between the oceans, the atmosphere, vegetation and land.

Now see little video of Hydrological cycle.

VIDEO OF HYDROLOGY CYCLE

SOURCES OF GROUND WATER1. Wells2. Spring3. Infiltration galleries4. Karez

1.WELLS It is a deep hole, generally cylindrical,

that is dug of drilled into the ground to penetrate an aquifer within the saturated zone.

Recharge the addition of new water to the saturated zone.

The water table in an unconfined aquifer rises in wet seasons and falls in dry seasons as water drains out of the saturated zone into rivers.

2.SPRING A spring is a flow of ground water at

the ground surface Springs Types:-

1. Stratum spring2. Valley spring3. Fault spring 4. Artesian spring5. Deep seated spring

Springs

3.INFILTRATION GALLERIES An infiltration galleries is a horizontal

conduit having permeable boundaries so that ground water can infiltrate into the same.

Three layers of graded around gallery are:-I. 16 cm ballast(25 to 50mm size) around

pipe.II. 16 cm large pebbles (12 to 24mm size) as

intermediate layer.III. 24 cm fine pebbles (3 to 10mm size) as

the outer layer.

Infiltration Galleries

4.KAREZ A Karez is an underground tunnel

driven into the hill side to tap water from the underground spring.

Karez channels are in use in Baluchistan and West Pakistan

KAREZ OF BALUCHISTAN

OCCURANCE OF GROUND WATER It is depended upon following

features:-I. The porosity of the rocks.II. The permeability of the rocks.

1.POROSITYI. Porosity is quantitative measures of

the voids present in the rock.II. Porosity = volume of voids x100/

total volume of metricalIII.It is classified 5 to 20% medium and

less then 5% small.

POROSITY VALUES OF FEW ROCK FORMATIONSSr.No Types of rock Formation Porosity %

1 Granite, Quartzite 1.5%2 Shale, slate 4%3 Lime stone 5-10%4 Sand stone 10-15%5 Sand and gravel 20-30%6 Only gravel 25%7 Only sand 35%8 Clay and soil 45%

2.PERMEABILITY Permeability is defined as the property

of rock or unconsolidated sediment to permit flow of ground though it.

Gravels are high permeable. Clays are less permeable. Granite rocks are impermeable.

COEFFICIENT OF PERMEABILITY(K)Sr.No Types of soil K,(cm/sec)

1 Clean gravel 1.0 and greater2 Clean sand (coarse) 1.0 - 0.013 Sand (mixture) 0.01 - 0.0054 Fine sand 0.05 - 0.0015 Silty sand 0.002 - 0.00016 Silt 0.0005-0.00001

7 Clay 0.000001 and smaller

ZONES OF UNDERGROUND WATER With respect to existence of water at

different depths, the earth’ s crust can be divided into two major zones namely.i. Zone of rock flowage.ii. Zone of rock fracture.

ZONES OF UNDERGROUND WATER

ZONE OF ROCK FLOWAGE The depth of the zone of rock flowage

is not accurately known, but is generally estimated as many miles.

Interstices are generally absent in this zone, because the stresses are beyond the elastic limits, and the rocks remain in the state of plastic flow.

Water present in this zone is known as internal water.

ZONE OF ROCK FRACTURE It this zone, the stresses are within the

elastic limits, and depends upon porosity.

The maximum depth of this zone below the ground surface, varies in the range of about 100m to 1000m or more.

The zone of rock fracture.i. Zone of aeration.ii. Zone of saturation.

TERMS RELATED TO GROUND WATER1.Aquifer:

An aquifer may be defined as geological formation that contains sufficient permeable materials which permits storage as well as movement of water through it under ordinary field conditions.

2.Aquiclude: An aquiclude may be defined as

geological formation of relatively impermeable material which permits storage of water but it is not capable of transmitting water in sufficient quantity.

TERMS RELATED TO GROUND WATER3.Aquitard:

A geological formation that has poor permeability, but through which seepage is possible, and hence, it does not yield water freely to wells. It may transmit vertically appreciable quantities of water to from adjacent aquifers.

4.Aquifuge:An aquifuge may be defined as a

geological formation of relatively impermeable material which neither contains nor transmits water.

TERMS RELATED TO GROUND WATER4.Porosity (n):

Porosity of soil or a rock may be defined as the ratio of volume of voids to the volume of the material.

5.Coefficint of Permeability (K):The coefficient of permeability is

defined as the velocity of flow which will occur through the total cross-sectional area of the soil under a unit hydraulic gradient.

TERMS RELATED TO GROUND WATER6.Coefficint of Transmissibility (T):

The coefficient of transmissibility is defined as the rate of flow of water in (m.cu/day) through vertical strip of aquifer of unit which (1m) and extending the full saturation height under a unit hydraulic gradient, at a temperature of 60 F.

TYPES OF AQUIFERSAquifers are mainly of two types:

UNCONFINED AQUIFER CONFINED AQUIFER

UNCONFINED AQUIFER Unconfined aquifer is one in which

water table forms the upper surface of the zone of saturation.

It is known as water table aquifer or Phreatic aquifer or non artesian aquifer.

CONFINED AQUIFER Confined aquifer is one in which ground

water is under pressure greater then atmospheric pressure by overlying relatively impermeable strata.

It is known as artesian aquifer or pressure aquifer.

DIFFERENCE BETWEEN CONFINED AND UNCONFINED

AQUIFER

In confined aquifer water is stored below impermeable layer at pressure higher than the atmospheric pressure

It is also called artesian aquifer.

In unconfined aquifer water is stored in the top pervious soil layers.

It is known as water table aquifer or Phreatic aquifer or non artesian aquifer.

Confined aquifer Unconfined aquifer

UNCONFINED And CONFINED AQUIFERS

GEOLOGICAL CONTROLS OF GROUND WATER MOVEMENT

Ground water movement in the zone of aeration takes place under the influence of gravity. But the factors influencing water movement in the zone of saturation are of different kinds. Most of them are geological and are as follows:-1. Permeability of rocks.2. Attitude of bedding3. Buried river channels and unconformities.4. Hydraulic gradient.

GROUND WATER EXPLORATION “Ground water Prospecting”

means searching for the ground water.

Ground water investigations are of three kinds:-1. Geological investigations.2. Geophysical investigations.3. Hydrological investigations.

1.GEOLOGICAL INVESTIGATIONS. It is the most important and e main

deciding factor. The other two provide only supplementary information

Geological investigations, comprises of the following:-i. Study of rock types.ii. Study of topography.iii. Study of weathering.iv. Study of geological structures.v. Study of intrusive rocks.vi. Geological mapping.

2.GEOPHYSICAL INVESTIGATIONS

It is the based on the fact that rock formation differ in their in gravitational, magnetic, seismic and radioactive behavior.

The sub-surface geophysical methods involve recoding variations in temperature, resistivity, conductivity, spontaneous potential and response to gamma radiation and acoustic waves with increasing depth

3.HYDROLOGICAL INVESTIGATIONS

In the hydrological investigations the following studies are made:-i. Study of depth of water table.ii. Study of surface water table.iii. Study of springs and seepage.iv. Quality of water.v. Study of rainfall and climate.vi. Pumping tests.