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ثسن الله الطحوي الطحين

NETWORKS of WATER

3/)شبكبث المُبه ومعذاتهب(rd

- Class Dr. Sataa A. Al-Bayati (10-11)

INTRODUCTION )المقذمت(

Facts about water:

1. To ensure our basic needs, we all need 20 to 50L of water free from

harmful contaminants هلىثبد() each and every day.

2. 2005, Drinkable water is becoming increasingly scarce ًبزض() . By the

year 2025, it is predicted that water deficit عجع() will increase by 50%

in developing countries ثلساى ًبهيخ() and 18% in developed countries ثلساى )

.as population growth & development drive up water demand ,هتقسهخ(

3. Every 8 seconds a child dies from drinking contaminated water (that is

10 000 a day).

Fig. (1) Water Distribution in the Earth

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The Hydrologic Cycle)دورة المياه(

Fig. (2) water cycle

The water cycle contains the following elements:

1. Precipitation السقيظ() of all forms of water which falls from the

atmosphere to the earth's surface.

2. Infiltration التسطة() of precipitation deep into the ground, will

replenishing the ground water supply.

3. Runoff of precipitation across land surfaces and to streams, lakes, &

ocean.

4. Evaporation from surface water, soil and vegetation, returning

water vapor to the atmosphere.

5. Transpiration التعطق() by plants through their roots to their leaves, will

returning water vapor to the atmosphere.

Objectives of Water Supply Systems )أهذاف أنظمت تجهُز مبء الشرة(

1. Safe supply.

2. Adequate quantity

3. Available at any time.

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Elements of Water Supply System )عنبصر نظبم تجهُز المبء(

A. Source of supply هصسض التجهيع() .

B. Collection system ًظبم التجويع() .

C. Treatment plant هحطخ الوعبلجخ() .

D. Distribution system ًظبم التىظيع() .

A. Source of Supply

Waters come in form of precipitation.

1. Surface water supply

Water is running across the surface of ground, e.g. rivers, streams,

lakes, ponds, & reservoirs.

2. Groundwater supply

Water seeps into the ground, e.g. springs, wells, etc.

Fig. (3) Source of Supply

WT

P

Source Intake Pumping

station

Transmission

main

Treatment

plant

Distribution

system

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Water Source Requirements)هتطلجبد تجهيع الوبء( :

1. Quantity

Enough quantity at any time.

2. Quality

Safe & free from pollution.

3. Cost

B. Collection System

It conveys water from a source to a treatment plant.

a. Intake)الوأذص(

It is a structure placed in a surface water source to permit the

withdrawal)سحت( of water from this source.

Factors of designing intakes:

i. Location of the best water quality.

ii. Fluctuations تصثصثبد() of water level.

iii. Characteristics of intake site, e.g. water depth, river bed, waves

effects, formation of sand bars, navigation requirements,

currents, & floods.

iv. Pollution sources,e.g. wastewater treatment plants, factories,

etc.

Types of intakes:

i. Intake tower ثطجي() , Fig. (4)

ii. Submerged intake هغوىض() , Fig. (5)

iii. Intake pipe أًجىثي() , Fig. (6)

iv. Movable intake هتحطك() , Fig. (7)

v. Shore intake سبحلي() .

Fig. (4) Tower water intake for a reservoir or lake water supply

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Fig. (5) Submerged intake used for both lake and river sources

Fig. (6) Pipe intake

Fig. (7) Movable intake

b. Low Lift Pumping station

It pumps water to treatment plant.

c. Transmission main

A pipeline used to deliver water to treatment plant.

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C. Treatment Plant )محطت المعبلجت(

All water used for supply originates from the atmosphere as precipitation

(rain, snow and hail). This collects either above ground in rivers, natural

lakes, man-made impounding reservoirs or below ground in aquifers. Water

rapidly absorbs both natural and man-made substances generally making the

water unsuitable for drinking prior to some form of treatment.

The objective of water treatment is to produce an adequate and continuous

supply of water that is chemically, bacteriologically and aesthetically

pleasing. More specifically, water treatment must produce water that is:

(a) palatable (i.e. no unpleasant taste);

(b) safe (i.e. does not contain pathogens or chemicals harmful to the

consumer);

(c) clear (i.e. free from suspended solids and turbidity);

(d) colourless and odourless (i.e. aesthetic to drink);

(e) reasonably soft (i.e. allows consumers to wash clothes, dishes,

themselves, without use of excessive quantities of detergents or soap);

(f) non-corrosive (i.e. to protect pipework and prevent leaching of metals

from tanks or pipes);

(g) low-organic content (i.e. high-organic content results in unwanted

biological growth in pipes and storage tanks).

Groundwater is generally much cleaner than surface waters and so does not

require the same degree of treatment, it is required to remove:

Hardness, iron, & sometimes bacteria.

Surface water requires more complex treatment due to poorer quality, it is

required to remove:

Turbidity, color, taste, odor, & bacteria.

Treatment units )وحساد الوعبلجخ(:

Screening → Chemicals addition → Sedimentation → Filtration

↓

H.L. Pumping station ← Storage ← Disinfection

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Fig.(8) Water Treatment Plant

D. Distribution System

After treatment the finished water has to be conveyed to consumers. This is

achieved using a network of pipes known as water mains. This system must

supply water with the required quantity & pressure. It includes: pipes,

storage tanks, pumps, fire hydrants, & valves.

Distribution mains are the network of pipes that bring the water from the

service reservoir to the consumer's property. The network is highly

branched, to which connections to individual houses are made. Distribution

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mains form loop systems, which equalize the pressure, and ensures the water

is used rapidly and kept mixed. The distribution network comprises of pipes

of various sizes ranging down from 18 to 6 in.

Classification of distribution systems )تصٌيف أًظوخ التىظيع(:

1. Gravity distribution )التىظيع ثبلجبشثيخ(

High level lake or reservoir supply water to the system. It is safe &

reliable.

Fig.(9)Gravity-fed system. (Source: Julian Thornton.)

2. Direct pressure distribution الوجبشط ثىاسطخ الوضربد()التىظيع

Water is pumped directly into system.

Problems are due to failure in power-supply & pressure fluctuation.

It required number of pumps of varying capacities & good O & M.

3. Pumping & storage system (Direct-indirect system) (Dual system)

)التىظيع الوعزوج هي ضد هجبشط وذعى(

When the demand exceeds the pumping rate, the flow into the

distribution system is from pumping station & elevated reservoir. When

the pumping is more than the demand, the excess of water is stored in the

reservoir.

This system is economic & reliable.

It provides uniform pumping rate & chances of damage to pipe

appurtenances due to pressure variation is reduced and the stored water is

used for fire demands & pump breakdown.

Minimum pressure in the pipeline at the highest point can be guaranteed.

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Fig.(10)Pump-fed system. (Source: Julian Thornton.)

Well Types

A. Open wells

They are used mainly for three purposes:

(1) to extract ground water from fine grained aquifers of shallow depth,

which requires a large area of contact with the aquifer, and

(2) to serve as reservoirs for ground water slowly replenishing the well.

The yield potential of a well is evaluated on the basis of hydrological

conditions of the area—rainfall, runoff and recharge.

Advantages:

1. They do not require sophisticated equipment & skilled personnel for

construction. Different masonry materials, such as stones, bricks & concrete

blocks, are used as lining materials.

2. They can be operated by indigenous water lifts driven by man or animal

power, or low-cost mechanically operated centrifugal pumps.

3. Open wells can be revitalized by deepening or providing bores at the

bottom or sides.

4.Open wells may be either circular or rectangular in cross-section.

Limitations:

1. Large space is required by the well structure and for dumping excavated

material.

2. Construction of well is slow & laborious.

3. They are susceptible to contamination or pollution from surface sources,

unless properly protected.

4. Due to shallow water table there are large water level fluctuations & there

is possibility of the well drying up, especially during drought periods.

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Open well types

(i) Unlined wells

Well dug for purely temporary purposes, Fig.(11). To ensure stability, the

depth of unlined wells is limited to about 6.5 m.

(ii) Wells with pervious lining

They are usually lined with dry bricks or stone masonry. Water flows from

the surrounding aquifer into the wells through the sides of the well. Pervious

lining is suitable when the water-bearing formation consists of gravel or

coarse sand deposits. When the formation consists of layers of fine sand, the

sand particles escape along with water into the well, through the pervious

lining. As a result, a hollow space or cavity is formed behind the well lining,

thus endangering the structural stability of the well. The annular hollow

space around the well lining will be self-sealing in loose formations but, in

cohesive materials, it must be filled with brick or stone ballast. The ballast is

about 2 cm in size and packed behind the lining. It should extend at least

upto the static water table. Fig.(11) shows the typical cross-section of a well

with pervious lining. The following procedure can be adopted to construct

wells with stable pervious linings:

A 30 cm deep lining is constructed over the well curb, in cement mortar. The

remaining part of the well lining, upto the static water level, is laid dry

without mortar, with the exception that 30 cm strips of lining in cement

mortar are provided after every 1.25 m of dry lining.

Above the water table, the lining is constructed in cement mortar up to the

top.

When the rate of withdrawal of water from the well is not excessive, and

where aquifer and subsoil conditions permit, pervious lining is economical

and lasting.

Fig.(11) Unlined & with pervious lining

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(iii) Wells with impervious lining

Open wells with permanent masonry lining, laid in cement mortar, are

commonly used in alluvial formations (Fig.12).

Once constructed, they form a permanent structure for tapping water, as long

as ground water conditions remain favorable. Though wells with impervious

linings are usually deeper than the two types described earlier, their depths

generally do not exceed 30 m as, beyond that, the cost becomes excessive

and the well tends to be uneconomical.

Such linings are provided with weep holes for the lateral entry of water.

Wells with Reinforced Cement Concrete (RCC) linings are also sometimes

used, especially for higher depths. In some shallow watertable regions, RCC

collar wells, sometimes referred to as ring wells are used, though mainly for

domestic water supply.

Fig.(12) Well with impervious lining

(iv) Dug-cum-bore wells

Dug wells are sometimes provided with vertical bores at their bottom, to

augment their yields, Fig.(13).

Boring consists essentially of drilling small diameter holes of sizes ranging

from 7.5 to 15 cm in diameter, through the bottom of the well, and extending

them upto or into the water-bearing formation lying underneath the bottom

of the dug well.

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Fig. (13) Dug-cum-bore well

B. Tube wells Tube wells are classified:

1. Entry of water

(a) Screen wells

(i) Strainer wells

(ii) Slotted pipe gravel pack wells

(b) Cavity wells

2. Method of construction

(a) Drilled wells

(b) Driven wells

(c) Jetted wells

3. Depth

(a) Shallow wells

(b) Deep wells

4. Type of aquifer

(a) Water table wells

(b) Semi-artesian wells

(c) Artesian wells

1. Based on Entry of water

a) Screen wells

They using screens to permit the entry of water from the surrounding aquifer

may either be strainer wells or slotted pipe gravel-pack wells.

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Plain pipes and screens are lowered into the bore hole. The screens are

located opposite the water bearing strata. A bail plug is provided at the

bottom of the pipe and strainer assembly.

Fig. (14) Screen well

b)Cavity tube well

It (Fig.15) is a shallow tube well drilled in an alluvial formation. It does

not have a strainer, but draws water through the bottom of the well pipe.

Fig. (15) Schematic sketch of a cavity well

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2. Based on Method of construction

(a) Drilled wells

They are constructed by making bore holes, using percussion and rotary

drilling methods.

Plain pipes and screens are lowered into the bore hole.

Tube well construction involves drilling the bore hole, installing the casing

and well screen, and developing the well to ensure sand-free operation at

maximum yield.

(b) Driven wells

A driven well consists of a pipe and well point which are forced into the

water-bearing formation by driving with a wooden maul, drop hammer or

other suitable means. Driven tube wells usually vary from 3 - 7.5 cm in

diameter. They develop small yields and their construction is limited to

shallow depths

(c) Jetted wells

They are constructed with hand-operated equipment or power-driven

machines, depending upon the type of formation and the size and depth of

the well.

3. Based on Depth

(a) Shallow wells

They are of low capacity. The average depth of the well is usually less than

35 m.

(b) Deep wells

They are wells of high capacity, tapping more than one aquifer. Their depth

usually ranges from 60-300 m.

4. Based on Type of aquifer

(a) Water table wells

These are installed in unconfined aquifers which are under water table

conditions

(b) Semi-artesian wells

The water is under pressure, but not so high as to flow out of the well.

(c) Artesian wells

A flowing well gets its supply from an aquifer where the water is under such

high pressure that it overflows at the top.

WATER REQUIREMENTS )أحتُبجبث المبء(

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Volume: gal (U.S) = 3.79L

Pressure: bar = 10m = 98kPa (SI)

Pressure: psi = 1b/in2 = 6.9kPa (E-SI)

Area: ha = 10,000m2

Area: acre = 4047m2

Consumption = use = demand = استهلاك

The consumption of water can be calculated by, gpcd or Lpcd.

gpcd = gallons per capita per day غبلىى هبء لكل شرص يىهيب"() .

Lpcd = litter per capita per day لتط هبء لكل شرص يىهيب"() .

gpcd = Total annual consumption, g / (Population × 365)

or

Detail calculation for each activity.

Why we do not take the consumption of any day?

Design period = 25 - 40 years.

Factors Affecting gpcd:

1. Size of city)حجن الوسيٌخ(

Increase of size → more water consumption

As increase industrial use, more parks, more commercial use, etc.

2. Characteristics of people (economic conditions))الوستىي الوعيشي(

High-class residential areas consumed more water than others. For

gardening, car washing, air cooling, & pools.

Increase of economic status of people → more water consumption.

3. Climatic Conditions)الوٌبخ(

More water is used in warm, dry climates, than humid & cold

climates for bathing, gardening, air cooling, etc.

Regions subject to extreme cold (e.g. north of Iraq) has high

demand to prevent freezing of water lines.

4. Commerce & Industries )التجبضح والصٌبعخ(

Industry uses large volumes of water:

To produce → 1-ton paper → water: 2,000 – 100,000g

1-ton aluminum 35,000 – 56,000g

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1-ton steel 1,500 – 50,000g

Commercial areas include offices, shops, warehouses, & stores.

Commercial use ≈ 10gpcd, or

10,000 – 50,000g/acre/day, (50- 1500m3/ha/day)

5. Water Pressure )ضغظ الوبء(

More pressure: a) greater loss through leaks

b) increase volumes of flow through fixture units

per time.

More pressure → more water consumption.

E.g. water-use rate increased by 30% for a 20psi change in line

pressure.

6. Water Quality)ًىعيخ الوبء(

Improvement of water quality → more water uses & feeling safety

↓

More water consumption

7. Sewerage Facilities )تىفط شجكخ هبء هجبضي(

Sewers availability → no limitation on water use

↓

More water consumption

8. Water Rates & Metering )تىفر تسعُرة ومقبَُس للمبء(

Meters with high cost water → repair leaks & good water using

↓

Low water consumption

Using meters with certain cost of water in some countries reduce

water use by 40%.

9. Nature of Supply)طجيعخ التجهيع(

Intermittently water supply (parts of day) → decrease losses &

good water use

↓

Low water consumption

10. Availability of Private Supplies)تىفط هصبزض تجهيع ذبصخ(

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People & industries may develop their own private supplies from

wells or rivers. This will reduce water consumption.

11. Efficiency of the Management )كفبءح الازاضح(

Good management → Control of losses→ Low water consumption

12. Environmental Education )الىعي الجيئي(

Reduce water consumption.

Municipal Consumption of Water )الاستهلاك البلذٌ للمبء(

1. Domestic use ()الوٌعلي

Houses & private buildings.

Uses: drinking, bathing, cooking, sanitation, etc.

2. Industrial & Commercial Use

Offices, stores, hotels, factories, & refineries.

3. Public Use

Schools, colleges, hospitals, cinemas, theatres, mosques, parks,

gardens, fire fighting, sprinkling streets, public fountains, etc.

4. Loss & Wastes

Bad plumbing, pipes breakage, unauthorized connections, etc.

PREDICTION OF POPULATION )تنبؤّ السكبن(

Population may be predicated from knowledge of the city and its

environments, commerce & industries, etc.

A Swiss company (Electrwatt) in 1980 studies the population in Baghdad

city based on the data of censuses of 1965 & 1977. They find out the

average rate of increase of population is 3.4% & estimated population on

2000 will be 6.5 to 7.5million person.

In Baghdad city, 2000, the prediction of population depends on information

obtained from Ministry of Planning from the two last census of population

of 1965 & 1977.The information is,

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Total population = 5 423 964person.

Population growth rate = 2.3%

Population density = 1191person/km2.

The population changes due to;

1. births

2. deaths

3. migration

Main detailed factors for population change;

1. period of forecast: period increase → accuracy decrease, why

2. population of the area: population decrease → accuracy decrease, why

3. rate of increase of population: rate increase → accuracy decrease, why

Prediction Methods

1. Uniform Growth Rate( Arithmetical Progression) )معذل النمى المىحّذ(

A constant increment of growth is added periodically.

Example (1):

If the population increased from 90 000 to 100 000 during years 2005

to 2010 respectively, find the population at 2015.

Solution:

At 2005 → 90 000

2010 → 100 000

Increment = 100 000 – 90 000 = 10 000

At 2015 → population = 100 000 + 10 000 = 110 000

2. Uniform Percentage Growth Rate )معذل نمى النسبت المئىَتِ المىحّذ(

A constant percentage of growth is assumed for equal periods of time.

Example (2):

If the population increased from 100,000 to 110,000 during the past

decade (2000 – 2010), find the population at 2020.

Solution:

Increment, % = (110 000 – 100 000) / 100 000 = 10%

At 2020 → population = 110 000 × (1 + 0.1) = 121 000.

3. Graphical Extension (Curvilinear) ) ٍالإمتذاد التخطُط(

The population time curve is extended into future date by eye-

estimation.

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4. Graphical Comparison (Modified Curvilinear) )المقبرنت التخطُطُت(

The population-time curve of the city is extended into the future based

on a comparison with population-time curve of similar cities.

5. Empirical Method (Geometrical Progression) )الطرَقت التجرَبُت(

Hardenberg equation,

Pf = Pp (1 + r)n

Where:

Pf = future population,

Pp = present population,

r = rate of yearly increase,

n = number of years.

When the population data of the past years are available, then r can be

computed,

______

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r = n√ P2 / P1 – 1

Where:

P1 = population data in a year

P2 = population data in a later (n) year.

Example (3):

The population of a city was 124 000 in 1995 and 156 000 in 2005.

a) What was the annual rate of increase?

b) What will be the population in 2015?

Solution:

_______________

r = 10

√ 156 000 / 124 000 – 1

= 0.023

= 2.3%

Pf = 156 000 (1 + 0.023)10

= 196 000

6. Least Square Parabola )قطع مكبفًء المربعبث الصغري(

The population-time curve is assumed to be parabolic,

Y = a + bX + cX2

Where:

X = year

Y = population at year X,

a, b, c = constants.

To find a, b, & c use the following normal equations by applying

actual data,

∑Y = aN + b∑X + c∑X2 --- (1)

∑XY = a∑X + b∑X2 + c∑X

3 --- (2)

∑X2Y = a∑X

2 + b∑X

3 + c∑X

4 --- (3)

Where:

N = number of observations.

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Example (4):

The following table shows the population of a country during the

years 1910 – 2010, in ten years intervals.

a) Find the equation of the least square parabola fitting the data.

b) Compute the trend values for the years given in the table &

compare with the actual values.

c) Estimate the population in 2020 & 2030.

Year 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

Popu.,

million

23.2 31.4 39.8 50.2 62.9 76 92 105.7 122.8 131.7 151.1

Solution:

Make the following table,

year X Y X2 X

3 X

4 XY X

2Y Y

`

1910 -5 23.2 25 -125 625 -116.0 580.0 21.6

1920 -4 31.4 16 -64 256 -125.6 502.4 31

1930 -3 39.8 9 -27 81 -119.4 358.2 41.2

1940 -2 50.2 4 -8 16 100.4 200.8 52.2

1950 -1 62.9 1 -1 1 -62.9 62.9 64.0

1960 0 76.0 0 0 0 0 0 76.6

1970 1 92.0 1 1 1 92.0 92.0 90.0

1980 2 105.7 4 8 16 211.4 422.8 104.2

1990 3 122.8 9 27 81 368.4 1105.2 119.2

2000 4 131.7 16 64 256 526.8 2107.2 135

2010 5 151.1 25 125 625 755.5 3777.5 151.6

∑ 0 886.8 110 0 1958 1429.8 9209.0 886.6

N = 11

Y` = the computed population from the new equation.

Substitute in the normal eqs. (1), (2), & (3),

11a + 110c = 886.8 --- (4)

110b = 1429.8 --- (5)

110a + 1958c = 9209 --- (6)

Eq. (5) gives,

b = 13

From eqs. (4) & (6)

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a = 76.64, & c = 0.3974

Y = a + bX + cX2

Y = 76.64 + 13X + 0.3974X2

From this equation we can calculate Y` (Col. 9).

At 2020 → X = 6

Y = 76.64 + 13(6) + 0.3974(6)2

= 168.9million person

At 2030 → X = 7

Y = 187million person

Dictionary:

Contaminants هلىثبد() , scarce ًبزض() , deficit عجع() ,

developing countries ثلساى ًبهيخ() , developed countries ثلساى هتقسهخ() ,

Precipitation السقيظ() , Infiltration التسطة() , Transpiration التعطق() ,

withdrawal(سحت), Fluctuations تصثصثبد() , ,censuses )أحصبءاد( ,

Indigenous = أهليخ, revitalize = احيبء, laborious = هجهس, lasting = زائن,

tap water =هبء شطة , pervious = هسبهي, weep hole =فتحخ ًبضحخ , collar =طىق ,

percussion =زق , maul =هسقخ ,climate =هٌبخ , sewerage =هيبح فضلاد ,

commercial =تجبضي , industry =صٌبعخ , meter =هقيبغ , sanitation = عوليخ الترلص

, تأسيسبد صحيخ= plumbing , هي هيبح الفضلاد

References:

1. Michael, A.M., S.D. Khepar, & S.K. Sondhi, 2008, "Water Wells & Pumps", 2nd Ed,

2. Steel, E.W. & T.J. McGhee, 1979,"Water Supply & Sewerage", 5th

Ed., McGraw-

HILL.

3. Gray, N.F., 2005, "Water Technology", 2nd

Ed, Elsevier.