1. CHAPTER IV:
GROUNDWATER
BAUTISTA, GLADYS JOY B.
CE-5B

2. GROUNDWATER
Ground water is that part of precipitation that infiltrates through the soil to
the water table. An important component of water resource systems

3. SOURCES OF GROUNDWATER
Precipitation
Interception
Subsurface flow
Soil moisture

4. ZONES OF UNDERGROUND WATER
 Zone of aeration/ vadose zone
- a zone that contains both water and air
 Saturated zone
- where all the interconnected openings between rock
particles are filled with water

5.  Soil moisture- water in the upper layers of zone of aeration
 Groundwater- called the water in the zone of saturation
 Perched water table - when a small water body is
separated from the main groundwater body by a relatively
small impermeable stratum.
 Capillary fringe/ tension-saturated zone - the place
above the water table. In this region the pore space is
completely filled with water.
 Groundwater may be recharged or discharged

6. How ground water occur in rocks?

7. Two characteristics of all rocks that
affect the presence and movement of
ground water :
Porosity - size and amount of void spaces
Permeability -the relative ease with which
water can move through spaces in the rock.

8. Water table
 It is a surface of a water body that is constantly adjusting
itself toward an equilibrium condition.
 If there were no recharge to or outflow from the ground-water
basin, the water table would eventually become horizontal.

9. A 10-year well hydrograph showing climatic
effects on ground-water level.

10. Aquifer
 is an underground layer of water-bearing permeable rock or
unconsolidated materials (gravel, sand, or silt) from
which groundwater can be extracted using a water well.

11. 2 types of aquifer:
 Unconfined aquifers - are those into which water seeps
from the ground surface directly above the aquifer.

12.  Confined aquifer/artesian aquifer – are separated from the
ground surface by an impermeable layer and are generally at
greater depths than unconfined aquifers.

13. DISCHARGE OF GROUNDWATER
DISCHARGED BY:
TRANSPIRATION AND EVAPORATION
SPRINGS
SUBSURFACE FLOW
WELLS

14. Groundwater movement
 Groundwater flows underground in response to elevation
differences (downwards) and pressure differences (from
areas of high pressure to areas of low pressure).
Darcy's law relates
 the rate of the groundwater movement (Q)
 to the hydraulic conductivity (K),
 the cross-sectional area (A)
 and to the hydraulic gradient or slope of the water table (h/l)
 : The hydraulic conductivity depends on the permeability of
the rock and on the properties of the water. Water generally
flows in the direction of the hydraulic gradient and slope of
the water table.
Q= Kah/l

15. DETERMINATION OF PERMEABILITY
 PERMEABILITY
The ability of a substance to allow
another substance to pass through
it, especially the ability Of a porous
rock, sediment, or soil to transmit
fluid through pores and cracks.
 PERMEAMETERS
Device use to determine
permeability

16. Wells and Pump
Well is an excavated hole, usually a
vertical shaft, in the earth allowing
access to groundwater
Pumping a well lowers the water level
around the well to form a cone of
depression in the water table. If the
cone of depression extends to other
nearby wells, the water level in those
wells will be lowered.

17. HYDRAULICS OF WELLS
Static Water Level [SWL] (ho) is the
equilibrium water level before pumping
Commences
• Pumping Water Level [PWL] (h)
is the water level during pumping
• Drawdown (s = ho - h) is the
difference between SWL and PWL
• Well Yield (Q) is the volume of water
pumped per unit Time
• Specific Capacity (Q/s) is the yield per
unit drawdown

18. THIEM EQUATION
Unconfined Radial
Flow

19. Radial Confined Flow

20. OTHER WELL TESTS:
RECOVERY TESTS
SLUG TESTS
LEAKY AQUIFER TESTS
STEP DRAWDOWN TESTS

21. Types of Wells

22. SCHEMATIC DIAGRAM OF AUGER FLIGHT
AUGER FLIGHT
 FLIGHT – each section of
the auger

23. Sources of contamination in
groundwater
Salt contamination
Leakage and spills
Pesticides and fertilizers
Waste disposals

24.  Advection- describes movement of contaminant with and at the
speed of the moving water
 Dispersion- it leads to a spreading of concentration fronts as
they evolve over time and enhanced mixing of contaminated
water with surrounding uncontaminated water.
 Molecular diffusion- spreading of contaminants from the pore
space from regions of high concentration to low cow
concentration in response to concentration gradients
 Radioactive decay- results in the transformation of a
radioisotopes into one or more daughter products.
 Volatilization- phase transfer into soil gas in the unsaturated
zone.
 Sorption-absorption- transfer into soil and rock particles

25. MITIGATION
 Cleanup of contaminated groundwater tends to be very
costly. Effective remediation of groundwater is generally very
difficult.
 . Most of these treatment methods involve the filtration of the
contaminants of concern, and additional protection may be
garnered by installing well-casing screens only at depths
where contamination is not present.
 Well water for personal use is often filtered with reverse
osmosis water processors; this process can remove very
small particles. A simple, effective way of killing
microorganisms is to bring the water to a full boil for one to
three minutes, depending on location.

26. SHOCK CHLORINATION
Shock chlorination/well sanitation is
simply the process of adding a sanitizer to
the well in high concentrations to destroy
any bacterial growth. Shock chlorination is
effective in reducing an iron bacteria,
hydrogen sulfur, or coliform bacteria
problem