WASH Cluster – Groundwater Development and Drilling
GWD2
Session Plan
GWD2 – Characteristics of Groundwater Systems
Timetable
GWD1 - Occurrence
1 hour
GWD2 Characteristics of
Groundwater
Systems
1 hour 45 mins
GWD3 - Identifying
Potential Groundwater
Sources
GWD4 - Developing
Groundwater
Sources
40 mins
1 hour 45 mins
GWD5 - Protecting
Groundwater Sources
1 hour 10 mins
Timetable
Session-at-a-Glance
Session Activities
How groundwater enters aquifers
Approx. Time
15
Instructional Activity
EXERCISE 1: Groundwater flow
20
Groundwater movement through aquifers
25
Recharge Quiz, Discussion
and slides
Exercise in understanding
water levels
Discussion and slides
Groundwater Discharge
5
Slides, Q&A
EXERCISE 2: SPRINGS
10
CASE STUDY 1:
10
Refer to handout in exercise
2
review of case study
Climatic influences on groundwater
10
Variability of water quality
10
Total time for Session 2
Group Discussion on Climate
change
Slides and examples
1 hour 45 mins
Session Aims

To provide an understanding of how groundwater occurs in nature and how this can
influence the location of potential groundwater sources and the means of developing
the source
Session Objectives
By the end of the session participants will be able to:

List different geological features and how they influence the flow of groundwater
through the subsurface

Describe concepts of permeability - aquifers and aquitards

Describe groundwater flow through aquifers

Explain the influence of climate on groundwater occurrence and replenishment

Discuss the relationship of groundwater to topography and surface water
WASH Cluster – Groundwater Development and Drilling
GWD2
Session Materials

Computer and projector

Flip chart paper and pens

Clear plastic 1.5L bottle full of sand, with the cap covered with gauze, fine wire
mesh or coarse cloth

2L coloured water (red, blue or dark green)

Three clear 1.5 L plastic water bottles the same size, with the neck removed), ¾
Filled with 1;Coarse sand, uncooked wheat, rice (something with particle size
around 2-3 mm), 2; small pebbles (gravel) 3; alternating pebbles (gravel) and
fine material such as clay , talcum powder, flour

Three kettles – Plugs for the spout: a cork, rolled paper, a sock,

4 Samples of water with different salinity - A) fresh water, B) slightly salty
1000mg/L, C) 3000mg/L and D) 10,000mg/L (make these up by adding salt to
fresh water). Note the units are milligrams

Handouts:
- Bore location map
- Table of water level data
- Case study 1 handout
Session Plan
Trainer:
Present the slide and note each point –
Write on flipchart for later comment that the myths are
de-bunked
point 1 – already noted in the previous session, and see
below
Present the slide on Interconnection of pores and flow
Refer to the posters made in session 1 and the rock
samples if available
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Recharge Quiz: Refer to trainer notes for answers
Q1: What is the most likely SOURCE of water that might
get into the ground?
Q2: What do participants think the main factors
contributing to recharge will be
Q3: Consider which type of climatic environments are
most likely to have least recharge
Q4: In areas of limited recharge from infiltration. how
might aquifers be replenished?
Trainer:
Explain the means by which rainfall enters aquifers using
the slide
The slide is animated so it is self explanatory
Trainer: Introduce groundwater flow through aquifers
Have a clear plastic bottle full of sand, with the cap
covered with gauze, fine wire mesh or coarse cloth
Comment that this is a porous material that water flows
through (like an aquifer)– the exercise is to show that
water flows through an aquifer under an hydraulic gradient
Pour coloured water into the bottle so that the sand is
saturated and the water between the pores can be seen:
Lay the bottle flat – participants to note that little water
flows out
Tilt the bottle– participants to note that water seeps out
more rapidly
Q: What does this mean?
A: Groundwater flows from highest level to lowest level
and the higher the tilt (ie the gradient) the more the flow
Summarise by reference to the slide:
Do the following EXERCISE to show how real data is used
to work out flow directions
EXERCISE 1: Working out flow directions
Q: Why is it important to know groundwater flow
directions
A: To understand where groundwater is likely to be
flowing
Where groundwater might be closer to the surface
including where it might discharge
Direction of pollution sources
Trainer: hand out the maps of bore locations and table of
groundwater levels
See hand out details in the exercise below
An important point to bring out is that the elevation of the
water table needs to be understood – just like surface
water, groundwater flows from higher elevation to lower
So participants are to work out the groundwater elevation
in each bore, plot them on the map and work out the
direction of higher to lower groundwater elevation
Trainer: Use a flip chart to show how the information in
the table can be used to work out the groundwater
elevation – ie the difference between depth to
Session Plan – GWD2
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groundwater and elevation of groundwater
Participants to prepare a cross section to help visualise the
groundwater flow
Trainer:
Show cross section
Q: What is evident from the section?A: The groundwater level roughly approximates to ground
level
Q: What does this mean?
A: Groundwater flows from areas of highest level to areas
of lowest level
TRAINER:
Conclude with a comment that:
an aquifer is a like a layer of sponge
water fills the sponge
it seeps through the sponge from the highest point
to the lowest
You may want to demonstrate soaking a dry sponge and
tilting it to show the way the groundwater flows Refer back
to debunked myths – have we debunked myth 2
Groundwater is not static – it flows through pores in rocks
Trainer – demonstrate the seepage rate through different
materials:
ACTIVITY:
Have three clear plastic bottles the same size, (the bigger
the bottle the better – suggest around 1.5L water bottle
with the neck removed) Drill a few holes around the sides
near the bottom to allow drainage
Fill to around ¾ full with different material –
1;Coarse sand or uncooked wheat, rice (or something with
particle size around 2-3 mm
2; small pebbles (gravel)
3; alternating pebbles (gravel) and fine material such as
clay , talcum powder, or flour
All jars to be filled to the same height –
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GWD2
Three groups, each group with one of the jars and 1 to 2
cups (250 – 500 ml) of coloured water. Participants pour
into their jar gradually and see which seeps down most
quickly – it should be the pebbles, then sand then layered
material
Groups to comment on their observations
Trainer: Explain that the permeability of a rock
formation has an important impact on how groundwater
flows to shallow and deep aquifers. Essentially, the more
permeable layers allow more rapid and greater volume of
groundwater flow. Some materials have little permeability
and there is limited movement of groundwater - these are
known as Aquitards. In the case where there is no ability
for seepage to pass through a rock or soil this material is
considered to comprise an aquiclude. The aquitards are
the layers of fine material in jar 3 in the previous exercise.
The relative permeability of naturally occurring materials
is shown in the table (after Bear and Verruijt, 1987).
Note that the permeability of different consolidated rock
types is also reflected in the degree of fracturing that may
occur as discussed previously which provides a
“secondary” porosity.
Discuss the concept of permeability based on the previous
exercise – the water should have greatest difficulty
passing through the bottle with the finest material
Refer to the table and Point out:
Red line - shows decreasing permeability
Green line – shows most suitable aquifer
Trainer: Ask about consolidated rocks –
Q: why have they low aquifer potential
A: because the porosity and permeability depend on
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presence of fractures
The serious point to be made is that fractured rocks
are “hit and miss”, depending on the location and
extent of the fractures.
Trainer:
Refer to the slide – talk about which materials have best
ability to yield water in a well
The slide is animated to show the best yielding layers
Note: clays are very fine grained. They contain a lot of
water because they have very small particles BUT clays
have low permeability so water is not easily released
The lesson is that a well dug in sand or gravel will
yield much more water than one that is dug through
clay.
Going back to geology –areas where there is sand or
gravel have very good potential for extracting groundwater
Trainer: Use slide to mention
Confining layers are often clays or other low permeability
material
ACTIVITY: to show restriction to flow through an aquifer:
In groups; Each group to have a Teapot or small kettle.
Take the lid off for this exercise:
Fill slowly with water – keep it filling at the same rate as
water flows freely through the spout
Plug the spout with a cork: – keep trying to fill the kettle
– observe that water can’t get out through the spout and
tries to find an easier way out so it will spill over the top
(through the gap for the lid)
Take out the cork: plug with a range of materials with
different permeability - could try cotton balls, piece of
sponge, a piece of cloth (eg a clean sock?) or even rolled
up (toilet) paper
Each group to note qualitatively the different rate at which
water passes through the spout –
Comments on observations:
Imagine the spout as an aquifer:
The lesson here is:
When there is no restriction to flow, water will flow
though the aquifer without restriction
When there is restriction, the water tries to flow
through the spout but will either flow at a slower
rate or be forced to spurt out of the top (imagine it
as the ground surface)
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Trainer: refer to Slide;
Participants to discuss how the kettle acts like the aquifer
(the blue layers in the slide) and and is trying to find its
way out through the easiest pathway which could be the
spout or if there is no way out, through the space for the
lid.
The two brown layers (low permeability) act like the walls
of the kettle are the confining layers and confine the flow
and water is forced into the blue layer – as water
continues to enter the aquifer (blue layer) it builds up
pressure
When a bore is drilled the pressure forces the water to
flow up the bore towards the surface to release the
pressure
If there is a natural fracture, the water under pressure
forces its way to the surface
THIS IS A COMMON OCCURRENCE AND NEEDS TO BE
UNDERSTOOD
Trainer: To get participants thinking about where
groundwater seeps to the surface (often referred to as
groundwater discharge) ask the following:
Q: if groundwater flows from areas of higher head to
lower head, where do participants think it will ultimately
end up?
A1: Ultimately the sea but also rivers or lakes
A2: Could also be at springs where the water table
actually intersects the ground surface to allow the
groundwater to seep or flow out at springs
Follow up with the diagram below
Trainer: Use the slide to reinforce the idea that:
Water seeps into rocks and “recharges” aquifers
Groundwater flows down a hydraulic gradient (point out
the blue lines)
Then discharges at different parts of a landscape
Exercise 2:
Go back to the cross section we drew – look at the water
levels for January
Groups to Sketch the watertable in boreholes 1 and A to
be two metres below the surface
Refer to red line in the slide (it is animated so you can see
the comparison
Q: Would the water table intersect the ground surface?
What would be the result of this?
A: Springs would develop
What are the implications as a water source for an
emergency?
This is another important concept:
Participants are to hear that some spring sources
are not always going to be available or the flow can
reduce if the groundwater level drops
Introduce the concept that water levels can rise and
fall depending on climate and recharge –
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It is not that water just flows along a new path
Trainer:
Show the slide to show when we monitor water levels the
groundwater level can change due to climate and also due
to increased use of groundwater
Lesson is that water levels are not static and can be
influenced by natural and man made factors
Relevance to an emergency is that groundwater is not
“always there” at the same volume
Trainer:
Go back to the bottle with the coloured water that was
used above.
Have one participant tilt the bottle again and another put a
small hole in the plastic where the water can be seen
Observe that water will seep out of the hole: make the
hole bigger and see if the flow increases
Draw similarity to a spring in which the water in the
aquifer (ie the sand in the bottle) has a pathway to the
surface and discharges
FLIP CHART:
Draw a river as cross section
Present the 3 different scenarios–
Water table above the river
River at high flow and above water table
River well above water table
3 groups each with a separate scenario (each to draw the
cross section on flip chart) to describe how the
groundwater would flow into or away from the river or the
other way around
Groups to attempt to draw the flow lines on their cross
sections and explain flow
Discuss relevance to an Emergency Water supply for
discussion
A reduction in the amount of groundwater migrating to the
stream can limit the available supply particularly in dry
periods.
In wet seasons, flow of water in rivers (eg wadis in Africa)
can be a direct source of water, as the layers of sand in
the river bed are recharged – this provides a groundwater
Session Plan – GWD2
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GWD2
supply once the floods recede, (note the Chad case study)
Flood waters allow seepage from the river into surrounding
rocks to replenish groundwater resources taken from
bedrock.
Trainer: to point out that in coastal settings:
There is a salt water wedge beneath the fresh water
There is the potential for saline water to move landward as
better quality groundwater is pumped
Care is needed to avoid contamination of these aquifers
with salty water in coastal areas.
This is a problem that needed to be dealt with in response
to the Indian Ocean Tsunami where pumping of
groundwater from shallow wells caused up-coning of salty
water into the wells in some areas
Handout Tsunami case study if you have time (See
GWD2_HO_Tsunami case study)
Group Discussion on Climate change
What are the potential implications of climate change on
groundwater ?
Discussion points:
 Reduced recharge in areas where there is lower
rainfall
o lower availability
o also potential for increased demand
o perhaps increase in evaporation
 Some wetter areas to have higher rainfall and
greater intensity
o perhaps increased recharge
o not necessarily increased groundwater
recharge in the immediate area because of
increased surface runoff
o May be more recharge remotely from
increased stream flows and leakage
o with higher surface runoff, possible drainage
into existing wells (will mention again later
in pollution section),
 Changing water demand
o
as agriculture changes with climate change
o perhaps as population moves
Q: What defines drinkability
A: Primarily salinity
Have separate samples of A) fresh water, B) slightly salty
1000mg/L, C) 3000mg/L and D) 10,000mg/L (make these
up by adding salt to fresh water). Note the units are
milligrams
Label as A, B, C, D. Allow participants to taste (the water
is safe if it is only salt) – and point out which water is
drinkable, marginal or unpalatable. Using the flip chart
discuss the taste and salinity
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Q: What are the implications for an emergency?
Q: What factors will influence the quality of the
groundwater in an aquifer?
Participants to reflect on influence of recharge, and flow
through the aquifer:
Recharge – close to a river – controlled by salinity of
the river water
Recharge – if rainfall can enter quickly there will be
little evaporation at the surface before it recharges and
it will be in large enough volumes to keep the water
fresh
Proximity to the sea – if close could have salt water
intrusion from pumping
Evaporation of groundwater if groundwater is close to
the surface (can get salt pans, lakes etc)
The aquifer the water flows through – minerals that can
release different chemicals
Pollution (talk about in section 4)
Complete the session
Refer back to initial flipchart of Myths about groundwater –
Have we shown these are not true??
Did we meet the objectives?
Session Plan – GWD2
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WASH Cluster – Groundwater Development and Drilling
GWD2
QUIZ1: RECHARGE: (10 minutes)
See trainer notes for answers
EXERCISE 1: Bore Data Analysis Exercise
Hand out of: 1) Bore location map , 2) Table of water level data
Q: What features are shown on the map
A: Ground elevation contours, a river, scale, locations of bores, direction indicator
Things to note about the data –
Different names of the wells – can occur because of different sources, different bore
owners (eg Govt well, NGO, local community owned well etc)
This is a good data set with depths and elevations of all bores /wells known from
surveyed levels. If the elevations weren’t known, how could they be approximated
(Answer: estimated from the top contour)
Depth to water is the most easily measured piece of data (we’ll talk about that in
Monitoring)
The figure shows how to work out groundwater elevation – see whether the
participants can do this before putting this on a flip chart
Tasks:
Using the data from the table, work out the water table elevation for June
Plot the water table elevation at each bore / well on the map
Contour the water table elevation - work out flow direction based on the groundwater
elevations –
Q: Which direction is the hydraulic gradient? A: Generally southeast
What topographic feature is the likely discharge point for groundwater in this area –
Work out the groundwater elevations for January
Q: Are the levels the same? What are the differences?
A: There is clearly a seasonal variation of around 1-2m lower seasonal variation. Do all
bores show the same variation
What are the differences and what could they mean?

Bore 4: is 5.8m higher – this is possibly a bad measurement or the bore could be damaged
Session Plan – GWD2
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WASH Cluster – Groundwater Development and Drilling


GWD2
Bore B has had no change – suggests an incorrect reading or missed when the
measurements were taken so the June reading was copied
HDW(2) has much greater decline than nearby bores/ wells (HDW(1) and bore 5) – could be
due to much greater use, lower rate of recovery after use suggesting lower yield. in this
particular case it would indicate limited potential for this well as a large volume source.
Prepare a cross section of the water table and the ground surface – work out the depth
of water in each bore at both June and January
Q: How is the water table related to the topography What inferences can be drawn?
A: The water table tends to mimic the ground surface and tends to flow towards
drainage lines such as the river in this exercise
Participants are to appreciate that it is important to collect good quality
monitoring data (see later section) as erroneous measurements may be
misinterpreted. This is needed for proper planning such as predicting if a resource
is likely to run dry or change quality (by reversal of hydraulic gradient).
Q&A: Different terrains in which groundwater might be possible source – how would
you tell?
Session Plan – GWD2
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WASH Cluster – Groundwater Development and Drilling
GWD1A
Session Plan
GWD1A – Occurrence
13
Groundwater Development and Drilling
GWD1A
EXERCISE 2: Springs
Go back to the cross section we drew – look at the water levels for January
Now Sketch the watertable in bores 1 and A to be two metres below the surface
Q: Would the water table intersect the ground surface? What would be the result of this?
A: Springs would develop
What are the implications as a water source for an emergency?
References
Bhattacharya, & al, e. (2008). Groundwater for Sustainable Development: Problems, Perspectives and Challenges.
London: Taylor and Francis Group.
Cooray, P. (1967). An Introduction To The Geology of Ceylon. Colombo: The Government Press.
Leclerc, J.-P., Berger, C., Foulon, A., Sarraute, R., & Babert, L. (2007, May 7). Tsunami impact on shallow
groundwater in the Ampara district in Eastern Sri Lanka: Conductivity measurements and qualitative
interpretations. Retrieved March 10, 2010, from Science Direct: www.sciencedirect.com
Lytton, L. (2008). Deep Impact: Why post-tsunami wells need a measured approach. ICE , 42-48.
Panabokke, & Perera. (2005, January). Groundwater Resources of Sri Lanka. Retrieved March 2010, from
http://tsunami.obeysekera.net/documents/Panabokke_Perera_2005_Sri_Lanka.pdf
Piyadasa, R., Weerasinghe, K., Lakmal, H., & Maier, D. (2006). Groundwater quality changes in the tsunami
affected coastal belt - Southern Sri Lanka. 32nd WEDC International Conference (pp. 320-326). Colombo:
SUSTAINABLE DEVELOPMENT OF WATER RESOURCES, WATER SUPPLY AND ENVIRONMENTAL SANITATION.
Saltori, R., & Giusti, A. (2006). Challenges of tsunami and conflict affected rural water supply in Sri Lanka. 32nd
WEDC International Conference (pp. 523-529). Colombo: SUSTAINABLE DEVELOPMENT OF WATER RESOURCES,
WATER SUPPLY AND ENVIRONMENTAL SANITATION.
Tamil Information Centre. (2006, March 15). Sri Lankan Tsunami Situation Report: Report Number 6. Retrieved
April 2010, from UNEP: http://www.unep.org/tsunami/reports/Tsunami_Report_No_6.pdf
UNICEF. (2005). Guidelines for the rehabilitation of tsunami effected wells. Galle: UNICEF.
Villholth, K., Manamperi, A., & Buergi, N. (2006). Chemical Characteristics of Tsunami-Affected Groundwater and
Lagoon on the East Coast of Sri Lanka. 32nd WEDC International Conference (pp. 334-340). Colombo:
SUSTAINABLE DEVELOPMENT OF WATER RESOURCES, WATER SUPPLY AND ENVIRONMENTAL SANITATION.
Session Plan – GWD1A
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