This Slide deals with Sources, intake structures and water demand in Water Supply Schemes in Details Manner . All the Aspects Related to Source of Wate, Water Demand Calculations, Design Period Considerations has along with the population forecasting methods has been explained
4. Estimation of Water Demand- key parameter –
planning of Water Supply Scheme
Agriculture sector – more then 80% of total water
potential created in our country
Remaining portion we have to utilize
Improvement in Life style & industrial development push
up the per capita of water
5. Prediction of precise quantity- very difficult
Certain Thumb Rules & Empirical Formulae
Types of Water Demand-
1. Domestic Water Demand
2. Industrial Water Demand
3. Institutional and Commercial Water Demand
4. Demand for Public Uses
5. Fire Demand
6. Water Loss in Thefts and Wastes
6. Vary according to the Living Conditions
50 to 60% of Total Water Consumption
IS code- limit on domestic water consumption
between 135 to 225 lpcd
Minimum Water Demand- For a town with full
flushing system-200 lpcd
Minimized up to 135 lpcd for EWS & LIG
Developed countries like USA –
usually high as 340 lpcd .
7. Industries which are existing or likely to start in
future
vary with the types & number of industries
present in the city
In Industrial Cities Per capita requirement
computed to be as high as 450l/h/d as
compared to the normal industrial requirement
of 50l/h/d
8. On an average per capita demand of 20
l/h/d is usually considered , this demand
may be as high as 50 l/h/d for highly
commercial cities
9. S.No Type of Building Avg.lpcd
1 Factories a) Where Bathrooms are required to be provided 45
b)Where no bathrooms are required 30
2 Hospitals (Including Laundry per Bed )
a) Number of Beds less than 100 340
b) Number of beds exceeding 100 450
3 Nurses Homes and Medical Quarters 150
4 Hostels 135
5 Hostels(per Bed) 180
6 Restaurants per Seat 70
7 Offices 45
8 Cinemas, Auditoriums and Theatres (per seat) 15
9 Schools a) Day Scholars 45
b) Residentials 135
10. Water requirements for parks, gardening,
washing of roads etc
Normally 5% of Total water Consumption
Usual Range – 10 lpcd while computing total
water requirement
11. 1 lpcd – 50 Lac Population
Establishment of Fire Hydrants in the City
Following Requirements must be met for the
water demand
1) The minimum water pressure available at the Hydrant-
100-150 KN/m2( 10 to 15m of Water Head) & should be
maintained for 4 to 5 Hours of Use of Hydrant
2) Out of three jet stream – discharge from single stream-
1100l/m
12. For cities having population exceeding 50,000 the water
required in kilolitres may be computed using the
relation=100√P where P= Population in Thousand
Kuichling Formula- Q=3182 √P where P is population in
Thousand and Q is amount of water requires in
litres/minute
Freemans Formula-1136[P/5 +10]
National Boards of Fire Underwriters Formula- When
population is less than 2 Lakh, Q=4637√p[1-0.01√p]
Bustons Formula- It states that, Q=5663√P
All the above formulas suffer from the drawback that they are
not related to the type of district served and gives equal
results for Industral and Non. Industrial Aress
13. Water lost in leakage due to bad plumbing or damaged
meters, stolen water due to unauthorized water
connections
These losses should be taken into account while
estimating the total requirement
May be as high as 15% of the Total Consumption –
nearly equal to 55lpcd
14. Total Maximum Water Demand = Sum of Six Water
Demands
(Domestic Water Demand) +
(Industrial Water Demand)+
(Institutional and Commercial Water Demand)+
(Demand for Public Uses)+
(Fire Demand) +
(Water Loss in Thefts and Wastes)
Per capita demand = Total Yearly water
requirement of the city in litres
(i.e.V)/365* Population
15. Use Demand in l/h/d
1) Domestic Use 200
2) Industrial Use 50
3) Commercial Use 20
4) Civic or Public Use 10
5)Wastes and Thefts etc 55
6) Fire Demand Less than 1
Total=335 = per capita demand
17. 1. Size of the City
2. Climatic Conditions
3. Types of Gentry & Habits of People
4. Industrial & Commercial Activities
5. Quality of Water Supplies
6. Pressure in the distribution system
7. Developments of Sewerage Facilities
8. System of Supply
9. Cost of Water
10. Policy of Metering & Method of Charging
18. 1. Water tight joints
2. Pressure in the Distribution System
3. System of Supply
4. Metering
5. Unauthorized Connections
20. Smaller the town more variable is the demand
1) Maximum Daily Demand= 1.8 ×Average Daily Demand(q)
2)Maximum Hourly Demand
= 1.5 ×Average Hourly Demand of Maximum Daily Demand
=1.5 × (Maximum Daily Demand/24)
=1.5 ×(1.8 × q/24)
=2.7 ×(q/24)
=2.7 × Average Annual Hourly Demand
3)Maximum Weekly Demand=1.48 × Average Weekly Demand
4)Maximum Monthly Demand= 1.28 × Average Monthly Demand
21. The GOI manual on water supply has recommended the
following values of peak factor, depending upon the
population
Sr.No
.
Population Peak Factor
1 Up to 50,000 3
50,001 – 2,00,000 2.5
Above 2 Lakh 2
2 For Rural Water Supply Scheme,
where supply is effected through
stand post for only 6 Hours
3
23. In Order to avoid future complications of Expansion
Design period should neither be too long nor should it be
too short & should not exceed useful life of the structure
The future period or the number of years for which provision is
made in designing the capacities of various components of the
Water supply scheme is known as the Design Period.
Water supply projects under normal circumstances, may
be designed for a design period of 30 years excluding
completion time of 2 years.
24. S.No
.
Units Design
Discharge
Design
Period
1 Water Treatment Units Maximum Daily
Demand
15 Years
2 Main Supply Pipes(
Water Mains)
Maximum Daily
Demand
30 Years
3 Wells and Tube Wells Maximum Daily
Demand
30-50 Years
4 Demand Reservoir Average Annual
Demand
50 Years
5 Distribution System Maximum Hourly
Demand
30 Years
27. Based upon the assumption that the population
increases at a constant rate i.e. The rate of
change of population with time is constant
Where
Pn=Perspective or forecasted population after n
decades from the present(i.e. last Known
census)
Po=Population at present(Last Known Census)
n= number of decade between now & future
X= Average( arithmetic mean) of population
increase in the known decades
Pn = Po + nx
This method is of limited application, mostly used in
large and established towns where future growth has
been controlled
28. The basic difference between arithmetic & geometric
method is that in Arithmetic method no compounding is
done and in Geometric Method Compounding id done
every decade
In this method a constant value of percentage growth
rate per decade is calculated
Where Pn= Population after n decades
Po= Initial Known Population
r= √r1.r2.r3…….rm ( Average percentage growth rate per
decade)
Pn = Po (1+ r/100)n
This method is applicable to the cities with unlimited
scope for future expansion and where a constant rate of
growth is anticipated
29. According to this method population after n
decade is given by
Where x and y are average incremental increase
of population per decade and average
incremental increase resp.
x=average increase of population per decade
= x1+x2+…..+xp/p
y= Average of Incremental Increase
=y1+y2+…..+yp/p
Pn = Po + nx +n(n+1)/2*y
This method is adopted for cities which are likely to grow
progressively of increasing or decreasing rate rather
than a constant rate
30. In this method average decrease in the % increase is
calculated and then subtracted from the last % increase
computations made for each increased year
Calculate the % increase in population in each decade
and work out the decrease in percentage increase in
each decade and find average percentage decrease say
‘r’. The population of upcoming decade from the previous
known decade is given as
Where
Po=Population of the last known decade
ro = Growth Rate of last decade
r’= Average decrease in growth rate
P1=Po+(ro-r’/100)*Po
If Population is reaching towards saturation and growth
rate is decreasing, then this method is suitable.
31. This method is suitable when past record is available for
long duration and extension is required for small
duration
32.
33. Big and Metropolitan Cities are not allowed to
develop in haphazard & natural ways, but are
allowed to develop only in planned ways
The expansion of such cities are regulated by
various by laws of the corporations and other
local bodies
Only those expansions are allowed which are
permitted / proposed in the master plan of the
city.
This method can give us when and where the given
number of houses, industries and commercial
establishments would be developed
34. This method is valid for those
whose growths are parallel to
national growth
36. Sources of Water
Surface Sources
Sub-Surface
Sources
Pond and Lakes
Streams and Rivers
Storage Reservoirs
Ocean
Springs
Infiltration Galleries
Infiltration Wells
Wells and Tube Wells
37. Are sometimes called as Horizontal Wells
Infiltration Galleries
38.
39. Are the shallow wells constructed in series along the banks of
the river in order to collect the river water seeping through their
bottom.
Infiltration Wells
40.
41.
42. The natural outflow of ground water at the earths
surface is said to form a spring.
Springs are usually formed under three general
conditions of geological formation
1. Gravity Spring
2. Surface Spring
3. Artesian Spring
Springs
50. Site Should be Selected such that
Admit water even under worst condition of the flow in the river
As near as possible to the treatment works
At a place protected from rapid currents
It is free from pollution
It should not interfere with river traffic
Good Foundation Conditions are available & scouring will be less
Further Expansion is possible
51. Intakes are classified under Three Heads
Intakes
Submerged
Intake
Exposed
Intake
Wet Intake
Dry Intake
River Intake
Reservoir
Intake
Lake Intake
Canal Intake
52. Wet type Intake Well founded near river bed
River Intake is located at the Upstream side of the City
They are mostly located sufficiently inside the river
53. Where the River Bed is soft and unstable
The Intake Tower founded slightly away from River Bed
The Intake is kept submerged under lower water level of river
54.
55.
56.
57. When the flow in the river is not guaranteed throughout the year –
dam is constructed
The Reservoir Intake – Practically Similar to River Intake except
these are located at maximum depth of water
Design depends – Type of Dam
58. When the flow in the river is not guaranteed throughtout the year
– dam is constructed
The Reservoir Intake – Practically Similar to River Intake except
these are located at maximum depth of water
Design depends – Type of Dam
59.
60.
61.
62.
63. Sometimes- source- irrigation canal passing through the town
Does not cause appreciable resistance to the canal flow
Otherwise- located inside the canal bank and Canal bank is lined
