2. Distribution of the World’s Water
How much of the World’s water is fresh & available?
Our main source of water is groundwater
3. Hydro Cycle Revision
Water in the world is reused
Rain
Lakes and Streams
Groundwater
As well as being the largest %
of fresh water, what else is
good about groundwater
5. Permeability of Rock
Rock
Cracks in rock
Water travels through
cracks in rocks
If no cracks then water
cannot move
6. Advantages of ground water
Sand is
Permeable
Water is filtered through sand and gravel
More chance of
water availability
in summer
Reduced risk of contamination Stays at a stable temperature
7. Ground Water Storage: Aquifers
Movement of
water through
the ground
/rocks
Storage of
groundwater
Saturated Zone
8. Unconfined Aquifer A pump is required to
overcome this head
This difference in
height is called the
head required.
Water Table
Unconfined Aquifer
Non permeable rock/clay
No cracks for water to move
9. Confined / Artesian Aquifer
If head required>
pressure in aquifer then
pump is required
No pump required if
head required <
pressure in aquifer
Water in aquifer
is trapped so
pressure builds
up
Artesian/Confined
Aquifer
Non permeable rock/clay
No cracks for water to move
10. Head
Where you
want to collect
This difference in
water from
height is called the
head required. A pump is required to
overcome this head
Where water is
(water table)
11. Where would you build your well?
Shortest well, so
smallest head
B required & also
A close to house
C
D
Non permeable rock/clay
12. Where would you build your well?
C
A B
Wastage of water?
Storage Needed?
What are the issues
with your choice?
13. Effect of well on Water table
What do you think will
happen when we build a
well?
Original Water Table
16. What type of Well?
Bored or Drilled Well
Deep narrow well
Protected from pollutants
Can safely abstract water
Hand dug-normally quite
shallow
Open to pollution
Even the bucket and rope can
contaminate the water supply
17. Digging Wells
Hand drilled
Cant get that deep
Not advised to drillamount of water
Limited into
hard rock-not easy to
Use an auger
find connecting cracks
Jetting wells
After drilling, borehole Machine drilled
Use of water to
will need casing or well boreholes
loosen soil and
will need bricks to Drilling rig & crew
carry it to surface
support it Time and money
Sand/gravel/clay
–not rock Percussion drilling
Rotary drilling
18. Machine Drilled Boreholes: Cable
Percussion Drilling
Tripod
Not good for rock
Falls by gravity
Drilling shallow boreholes
Low cost & minimum disruption
19. Machine Drilled Boreholes: Rotary
Drilling
Exerts downward pressure and
drills rotationally all the way
down
Sharp,
rotational drill
bit rotates
round
20. Well Yield
Important to know the yield of the well so we know what pump to use
Prevent drawing down the well too much or effecting other wells
The Yield of an aquifer depends on the
1. Amount of water available
2. Rate at which it can be extracted
Depends on soil type or amount of cracks in the rock
A pumping test is done to estimate the yield of the borewell
21. Pumping Test Pump well for 8 to 48 hours.
Rate of water
pumped Distance to new water
=volume/time level/time
Tests the balance between
the max volume of water
pumped out and recharge
Normally carried out by Drawdown
Recharge
specialist contractors
Balance achieved
when water level stops
Recharge dropping. This is the
yield
22. Calculating Head Required: If Pump
Below Water
Total head to overcome=Static + Friction-Suction head
Height difference
between two
water bodies
Head needed to
get to pump
Bend in pipes etc
23. Calculating Head Required: If
Water Below Pump
Total head to overcome=Static + Friction + Suction head
Height difference
between two
water bodies
Head needed to
get to pump
Bend in pipes etc
24. Types of Pump: Positive
Displacement e.g.
Handpump
Fixed
volume of
liquid
pumped up
each time
Due to pressure
Liquid is physically change, water is Liquid is physically
displaced sucked up displaced
25. Hand Pump
Heavy pump handle to
Rod connects balance with the inside
handle to of the pump to make it
piston easy for user.
Rising Main carries
Valve the water to the
outlet
Valve Pump cylinder
pushes water to
rising main
Screen
Prevents stones and Foundation prevent
gravel but allows contaminating supply
water through
Depth= 50m or less
26. Hand Pump Check valve
open from
gravity
Check valve Check valve
closed closed
Foot valve
Foot valve Foot valve closed from
open from open from weight of
suction suction water
Suction pulls Suction pulls Piston moves
water up water up through water and
displaces water
27. Hand Pump
Check valve Check valve
open from open from
gravity gravity
Check valve
closed
Foot valve
Foot valve closed from Foot valve
closed from weight of closed from
weight of water weight of
water water
Piston moves Piston reaches Piston gets pulled up and
through water and bottom of displaces the water on top
displaces water cylinder. of piston. Also sucks up
more water from borehole
30. Types of Pump: Rotodynamic
Machine which moves quickly and passes this
kinetic energy onto a liquid.
If speed of pump increases=discharge &
pumping head increases
e.g. centrifugal pump
Water Water
(little speed) (lots of speed)
31. Centrifugal Pumps
Fast water
small area
through
pushed
Casing forces
water through
small space
Shaft turned by
Impeller gives (lots of speed)
water energy electric/diesel
Water
motor
Water
(little speed)
32. Centrifugal Pumps
Casing forces speed of water to
decrease as less area, this
increases the pressure. Water
gets lifted due to this pressure
Pressure = Force
Area
Impeller spins the water round
accelerating it.
Force=mass x acceleration
33. Operation of a Surface Mounted
Centrifugal Pump
Never run pump dry
If the pump is above the waterbody
then it cannot pump only air.
It needs primed
Priming means the pump casing
has to be filled with water before
starting the pump.
Better to start the pump against a closed valve-this reduces the
power needed for start
34. Multistage Pump
If the required head cannot be met by one centrifugal pump then a
multistage pump is used
Series of centrifugal pumps
Pressure of liquid is increased in stages
Can block easily and become damaged –so only good for very clean
water
Used for boosting water pressure and in submersible borehole pumps
35. Submersible Centrifugal Pumps
Waterproof pump
Push fluid to the surface
Series of impellers
Typically multistage
centrifugal pumps
Power supply
operating in vertical
position Water enters
here
Ensure pipe does not dry out
39. Simple Jet Pump
Suction Pipe
Venturi Underwater part of a deep well jet pump
Speeds up the Q=velocity x area
water causing Low presure
a pressure Change in pressure
High velocity is related to
drop. This
sucks in more High pressure change in velocity
water .
Pressure pipe
Half of water sent back through
Cone shaped nozzel
Venturi throat
Reduce area so increase
Pressure
40. Simple Jet Pump
Jet pumps are designed to pump large
volumes of water
41. What pump to use?
Pump Type Lifting from Abstract from Distribute
wells or rivers & lakes through
boreholes pipeline
Surface
mounted
centrifugal
Electric
submersible
multi-stage
centrifugal
Hand pump
42. Selecting the correct pump
Based on head to overcome and flow need to pump
Head
(m)
Pump Curves from
suppliers
m3/s
43. Vigyan Ashram Pump Exercise
Carry out a tour of Vigyan Ashram’s pumps
Complete the below table with all the information you
can find out
Location Type of Head Power How could this pump/well be
pump Rating improved?
44. Vigyan Ashram Pump Exercise
How could you improve these
pumps? This should be your
next environment project!
45. To select the correct centrifugal
pump
1. Calculate the flow rate. This will depend on the water use.
2. Calculate the static head.
3. Calculate the friction head
This will include the friction over the length of pipe and the
friction from local bends etc
4. Calculate the total head (static + friction)
5. Use Pump curves from suppliers to find the correct pump
46. Pump Head Example
Calculate the head a submersible pump down this borehole would require
You need to fill a 900 liter tank Assume you are using a 15mm
Due to cost of running a pump internal diameter PE pipe
and unreliability of electricity,
you aim to fill this tank in 30
mins.
5m
10m
1.What is the flow
8m
needed from the
pump?
So Flow required
= 900 liters = 30 liters = 0.5 liters
30 mins 1 min second
48. Pump Head Example
3.What are the friction head losses?
Remember these are due to:
A. Losses due to the length of the pipe (affected by the type of material)
B. Local losses due to bends in the pipe and entry and exit
5m
10m
8m
49. Pump Head Example
3.What are the friction head losses? First Hf = 10.9L x Q 1.85
lets look at losses due to the length of the C 1.85 x D 4.87
pipe.
Use the Hazen Williams
formula to calculate the
5m friction losses due to length
10m of pipe
8m
50. Pump Head Example: Hazen
Williams Formula Length of pipe (m)
Flow (m3/s)
Hf = 10.9L x Q 1.85
C 1.85 x D 4.87
Frictional head
loss (m) Internal diameter
of pipe
Coefficient
51. Pump Head Example
Hf = 10.9L x Q 1.85 L= 8m + 10m +5m=23m of pipe
C 1.85 x D 4.87
Q= 0.5l/s =0.0005m3/s
C= 150 for PE & PVC Pipe
Hf = 10.9 x 23 x 0.0005 1.85
150 1.85 x 0.015 4.87
D= 15mm= 0.015m
Hf=15m
5m
10m
Friction losses from the length of
the pipe is Hf=15m
8m
52. Pump Head Example
3.What are the friction head losses? First
lets look at losses due to the length of the
pipe.
5m
10m
8m
You can also use tables Hf = 23m x 0.9
from suppliers to =20.7m
calculate the head loss
due to length of pipe
53. Pump Head Example Coefficient of
bend/entry/exit
Velocity
hL= kL v2
3.Now lets look at local losses due to 2g
bends in the pipe and entry and exit
Exit Loss gravity
kL values
90°bends =1
5m Plain suction entrance=0.9
10m
Entry Loss Sharp exit=1
8m h = (3 x k 90°bends + k entrance + k exit) x v2
L L L L
2g
hL= (3 x 1+ 0.9+ 1) x v2
2g
Need to find the
velocity of the
water. V=Q/A
54. Pump Head Example
Cross sectional area of pipe
A=Πxd2
4 0.015m
A=3.14 x 0.0152
4
A=0.000177
Q= 0.5l/s =0.0005m3/s
V= Q = 0.0005 =2.83m/s
A 0.000177
hL= (3 x 1+ 0.9+ 1) x v2 hL= (3 x 1+ 0.9+ 1) x 2.832
2g 2 x 9.81
=2m
So local friction losses
account for 2m of head
55. Pump Head Example
3. S0 the friction losses are:
hk= 15m
A. Losses due to the length of the pipe
B. Local losses due to bends in the pipe and entry and exit hL= 2m
5m
10m
8m
56. Pump Head Example
Calculate the total head required
Total head = hstatic= 23m + Hk )= 15m + hL= 2m = = 40m
(due to length of (due to local
pipe) losses)
5m
10m
The more head we have to
overcome the more energy
we need to use.
8m
Can you think of any ways to
reduce this head?
Reduce number of bends
Chose a bigger diameter pipe
Chose a smoother material
Have bell shaped entry
57. Pump Head Example
So to find a suitable
pump. You need to look
at pump curves.
Head
(m)
40m
0.0005m3/s
Suitable pump m3/s
