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GROUNDWATER
DEVELOPMENT FOR PORTABLE WATER SUPPLY
ABSTRACT
Groundwater hydrology may be defined as the science of the occurrence
distribution, and movement of water below the surface of the earth.
Geochydrology has an identical connotation, and hydrogeology differs only by
its greater emphasis on geology. Utilization of groundwater dates from
ancient times, although an understanding of the occurrence and movement of
subsurface water as part of the hydrologic cycle has come only relatively
recently.
SCOPE:
Groundwater
referred to without specification is commonly understood to mean water
occupying all the voids within geologic stratum. This saturated zone
should be distinguished from an unsaturated, or earation zone where voids are
filled with water and air. Water contained in saturated zone is important
for engineering work, geologic studies and water supply development
consequently, the occurrence of water in this zones will be emphasized here.
Unsaturated zone a re usually found above saturated zones and extend uquad to
the ground surface. Because this water includes soil masture within the
root zone, it is a major concern for agriculture, binary, and soil
science. No rigid demarcation of water between the two zones is possible,
for they possess an interdependent boundary and water can move from owe zone to
the other in either direction. The interrelationships are described more
in some higher hydrogeology texts.
TABLE
OF CONTENTS
CHAPTER
ONE
1.0
Historical background and groundwater theories
1.1
Water theories
1.2
Recent centuries
CHAPTER TWO
2.0
Importance of groundwater
2.1
Groundwater in the hydrologic cycle
2.2
Occurrence of groundwater
2.3
Rock properties affecting groundwater
2.4
Vertical distribution of groundwater
2.5
Types of aquifers
CHAPTER THREE
3.0
Searching/exploration of groundwater
3.1
Methods of groundwater exploration
3.2
Groundwater basin investigation
3.3
Data collection and fieldwork
CHAPTER FOUR
4.0
Drilling for groundwater (wells)
4.1
Test whole and well logs
4.2
Methods for drilling shallow wells
4.3
Methods for drilling deep wells
4.4
Quality of groundwater
4.5 Measures of
water quality
4.6 Water
quality coterie
CHAPTER FIVE
5.0 Completion of
wells
5.1 Well development
5.2 Protection of
wells
5.3 Well
rehabilitation
5.4 References
CHAPTER ONE
HISTORICAL BACK
GROUND AND GROUND WATER THEORIES
Groundwater development dates from ancient times the Old Testament contains
numerous references to groundwater, springs, and wells, other that dug wells,
groundwater in ancient times we supplied from horizontal wells known as
QAUNATS. These persist to the present day and can be found in a band across the
regions of the South Western Asia and North Africa extending from Aghanistan to
Morocco. A cross section a long a qanat ie shown in fig 1.1 typically, a
gently sloping tunnel dug through alluvial material leads water by gravity flow
beneath the water table at its upper end to a ground.
FIG 1.1
A vertical cross section along a qanat surface outlet and irrigation canal at
its lower end. Vertical shafts dug at closely s paced intervals provide
access to the tunnel. Qanats are laboriously hand constructed by
skilld workers employing techniques that date back 3000 years.
Iran possesses the greatest concentration of qanats; here some 22,000 qanats
supply 75 percent of all water used in the country. Lengths of qanats
extend up to 30km, but most are less than 5km. The depth of the qanat
mother well (see fig 1.1) ie normally less than 50m, but instances of depth
exceeding 250m have been reported. Discharge of Qantas varies.
Seasonally with water table fluctuations and seldom exceed 100m3/hr.
GROUNDWATER THEORIES
Utilization of groundwater greatly preceded understanding of its origin,
occurrence, and movement. The writing of Greek philosophers to
explain origins of springs and groundwater contain theories ranging from
fantasy to nearly correct accounts. As late as the seventeenth century it
was generally assumed that water emerging from springs could not be
derived from rainfall, for it was believed that the quantity was in adequate
and the earth too impervious to permit penetration of rain water for
below the surface. Thus, early Greek philosophers such as Homer, Thates
and Plato hypothesized that springs were formed by seawater. Conducted
through subterranean channels below the mountains, then Aristotle suggested
that air enters cold dark caverns under the mountains where it condenses into
water and contributes to springs.
The Roman philosophers, including Seneca Pliny, followed the Greek ideas and
contributed little to the subject. An important step forward, however was
made by the Roman architect Vitnvius he explained the now accepted infiltration
theory that the mountains receive large amounts of rain that percolate through
the rock strata and emerge at their base to form streams.
The Greek theories persisted through the Middle Ages with no advances until the
end of the Renaissance. The French Poffer and Philosopher Bernard Palissy
(1510 – 1589) reiterated the infiltration theory in 1580, but his teachings
were generally ignored. The German astronomer Johannes Kepler (1571 –
1630) was a man of strong imagination, who likened the earth to a huge animal
that takes in water of the ocean, digests and assimilates it, and discharges
the end products of these physiological processes as groundwater and
springs. The seawater theory of the Greeks, supplemented by ideas of
vapourizaton and condensation processes within the earth, was restated by the
French Philosopher Rene’ Descarfes (1596 – 1650).
A clear understanding of the hydrologic cycle was achieved by the latter part
of the seventeenth century. For the first time theories were based on
observations and quantitative data. Three European countries made notable
contributions, although others contributed to and supported these
advances. Pierre Perrault (1611 – 1680) and estimated runoff of the upper
sein drainage basin. He reported in 1674 that precipitation on the basin
was about six times the river discharge, thereby demonstrating false the early
assumption of inadequate rainfall. The French Physicist Edme Mariotte
(1620 – 1684) made measurements of the same of paris and confirmed paraults
work. His publication appeared in 1686, after his death, and contained
factual data strongly supported the infiltration theory. Meinzer once
stated. Mariotte probably deserves more than any other man the
distinction of being regarded as the founder of groundwater hydrology, perhaps
I should say the entire science of hydrology”. The third contribution
came from the English astronomer Edmund Halley (1656 – 1742), who reported in
1693 on measurements of evaporation demonstrating that sea evaporation was
sufficient to account for all springs and stream flow.
RECENT CENTURIRES
During the eighteenth century fundamentals in geologic were established that
provided a basis for understanding the occurrence and movement of
groundwater. During the first half of the nineteenth century many
artesian wells were drilled in France stimulation interest in
groundwater. The French hydraulic engineer Henry Darcy (1803 –
1858). Studied the movement of water through sand. His treatise of
1856 defined the relation, now known as Darcy’s law, governing groundwater flow
in most alluvial and sedimentary formations. Later European contributions
of the nineteenth century emphasized the hydraulics of groundwater
development. Significantly contributions were made by J. Boussineq, G.A.
Daubree, J. Dupuru and A. Thiem. In the twentieth century, increased
activity in all phases of groundwater hydrology has occurred. Many
Europeans have participated with publications of either specialized or
comprehensive works. There are too many people to mention them all, but
R. Dachler, E. Imbeaux, K. Keihack are best known in the United States.
American contributions to groundwater hydrology date from near the end of the
nineteenth century. In the past 90 years, tremendous advances have been
made. Important early theoretical contributions were made by A. Hazem,
F.H. King while detailed field investigations were begun by men such as T.C
Chamberline, N.H Darton through his consuming interest in groundwater and his
dynamic leadership of groundwater activities of the U.S geological survey,
stimulated many individuals in the quest for groundwater knowledge. In
recent decadeds the publications of M.S. Hantush, C.E. Jacob. Within the
lat 20 years the surge in university research on groundwater problems, the establishment
of professional consulting firms specializing in water resources, and the
advent of the digital computer have jointly produced a competence for
development and management of groundwater resources that was nonexistent hereto
fore.
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