Classification either on quality or type based for groundwater can offer great advantages especially in regional groundwater management. It provides a short, quick processing, interpretation for a lot of complete hydro-chemical data sets and concise presentation of the results. There is a demonstrable need for a quality assurance, with the advanced usage of world's largest fresh water storage i.e Ground water. Its getting depleted over the years and the quality of the same degrading with a rapid pace. Ground water Quality is assessed mainly by the chemical analysis of samples. The data obtained from the chemical analysis is key for the further classification, analysis, correlation etc. Graphical and Numerical interpretation of the data is the main source for Hydro-chemical studies. In this paper we test the performance of the many available graphical and statistical methodologies used to classify water samples including: Collins bar diagram, Stiff pattern diagram, Schoeller plot, Piper diagram, Durov's Double Triangular Diagram, Gibbs's Diagram, Stuyfzand Classification. This paper explains various models which classify, correlate etc., summarizing the water quality data. The basic graphs and diagrams in each category are explained by sample diagrams. In addition to the diagrams an overall characterization of hydro-chemical facies of the water can be carried out by using plots which represents a water type and hardness domain. The combination of graphical and statistical techniques provides a consistent and objective means to classify large numbers of samples while retaining the ease of classic graphical presentation.

1. Graphical Presentation and Classification
for assessment of Groundwater Quality
presented by
Ravi Kiran JP
Email : kiran.ravi382@gmail.com
Department of Environmental Science &
Engineering
Indian School of Mines(ISM), Dhanbad
Jharkhand- 826004

2. Source of this Paper:
Study on spatial distribution of geochemical
characteristics in Groundwater of North Bengal
using GIS and its evaluation using statistical and
graphical techniques under NIH ROORKEE in
association with MINISTRY OF WATER
RESOURCES INDIA.
SR kumar, Scientist H, NIH Roorkee.
Assisted by Anshul Jain & Prashanth.

3. Ground Water
Water present in the subsurface environment of earth is
called Groundwater, an important component of water
resource systems.
Groundwater is the largest reservoir of fresh water that
is readily available to humans( 90% of Earth’s fresh
water).
Extracted from aquifers through pumping wells and
supplied for domestic use, industry and agriculture.
With increased withdrawal of groundwater, the quality of
groundwater has been continuously deteriorating.

4. Groundwater as an integral part of
Hydrological Cycle

5. Ground Water Quality Significance
Helps us understand the hydro-geologic
system.
Indicates comingling of groundwater and
surface water.
Helps us interpret groundwater flow
dynamics
Delineates groundwater contamination.

6. Ground Water contamination

7. Sources of GW Pollution

8. Effects of Ground water Pollution
Ground water contaminated with bacteria,
chemicals, pesticides, gasoline or oil can
result in various human health problems,
Ecological Imbalance etc.
It costs far less to prevent contamination
than to clean up.

9. One Example: Landfill Effects
• Waste acts as rectors to form Toxic Products
• These landfills also breeds harmful insects and organisms
• Spreads contagious diseases
• Ultimately Groundwater pollution

10. Groundwater resources
Management by Water Classification
How?
Compare ions with ions using chemical
equivalence
Making sure anions and cations balance
Use of diagrams and models.

11. Ground Water resources
Management by Water Classification
Why?
Helps define origin of the water
Indicates residence time in the aquifer
Aids in defining the hydrogeology
Defines suitability

12. Graphical Classification
Presentation of chemical analysis in graphical
form makes understanding of complex
groundwater system simpler and quicker.
The chemical parameters of groundwater play a
significant role in classifying and assessing water
quality.
The hydro chemical study reveals quality of water
that is suitable for drinking, agriculture and
industrial purposes

13. Contd..
Tables showing results of analyses of chemical quality of
ground water may be difficult to interpret, particularly
where more than a few analyses are involved.
To overcome this, graphical representations are useful for
display purpose, for comparing analyses, and for
emphasizing similarities and differences.
Graphical classifications can also aid in detecting the
mixing of water of different compositions and in
identifying chemical processes occurring as ground water
moves (Todd, 1980).

14. Graphical Presentation and classification for
assessment of GW Quality

15. Stiff Diagram
Stiff diagrams are graphical representation of water
chemical analyses, first developed by H.A. Stiff in 1951.
A polygonal shape is created from three or four parallel
horizontal axes extending on either side of a vertical zero
axis. Cations are plotted in milliequivalents per liter on
the left side of the zero axis, one to each horizontal axis,
and anions are plotted on the right side.
Stiff patterns are useful in making a rapid visual
comparison between water from different sources.

16. Stiff Diagram
Stiff Diagram –sample
Mg SO4
Ca
Na
HCO3
Cl
0

17. Typical Sample
Diagram

18. ADVANTAGES
• Can help visualize ionically related waters from which a
flow path can be determined, or;
• If the flow path is known, to show how the ionic
composition of a water body changes over space and/or
time.
DISADVANTAGE
• Only one analysis per plot.

20. Horsetooth Dam, Colorado-Big Thompson Project, Ft. Collins, Colorado

21. Piper Trilinear Diagram
A piper diagram is a graphical representation of the
chemistry of a water sample or samples.
The cations and anions are shown by separate ternary
plots.
The apexes of the cation plot are calcium, magnesium and
sodium plus potassium cations. The apexes of the anion
plot are sulfate, chloride and carbonate plus bicarbonate
anions.
The two ternary plots are then projected up onto a
diamond. The diamond is a matrix transformation of a
graph of the anions and cations

22. In Piper diagrams the concentrations are expressed as %meq/L.
Figure: Classification of hydrochemical facies using
the Piper plot.

23. % meq/l

25. A- Calcium type B- No Dominant type
C- Magnesium type D- Sodium and potassium type
E- Bicarbonate type F- Sulphate type
G- Chloride type
Subdivision of the diamond Characteristics of corresponding
subdivisions of diamond-shaped fields
1-Alkaline earth (Ca2++Mg2+) exceeds alkalies (Na++K+).
2- Alkalies exceed alkaline earths.
3- Weak acids (CO2-
3+HCO-
3) exceed Strong acids (SO2-
4+Cl-).
4- Strong acids exceed weak acids.
5- Magnesium bicarbonate type.
6- Calcium-chloride type.
7- Sodium-chloride type.
8- Sodium-Bicarbonate type.
9- Mixed type (No cation-anion exceeds 50%).

26. ADVANTAGES
• Many water analyses can be plotted on the same diagram.
• Can be used to classify waters by hydrochemical facies.
• Can be used to identify mixing of waters.
• Can track changes through space and temporal
relationships.
DISADVANTAGES
• Concentrations are renormalized.
• Cannot easily accommodate waters where other cations or
anions may be significant

27. Plotting a Piper Diagram
Ca + Mg
SO4 + Cl
Groundwater
Facies
SO4
HCO3 + CO3
Na + K
Cations Anions
Ca
Mg
Na + K HCO3 + CO3 Cl

28. Plotting a Piper Diagram
Cations Anions
Calcium-Magnesium
Sodium-Potassium
Chloride-Sulphate
Chloride-Sulpahte-Bicarbonate
Bicarbonate-Bicarbonate
Chloride-Sulphate
Calcium-Sodium
Sodium-Calcium

29. Plotting on a Piper Diagram
Ca
Mg
SO4
Ca + Mg
SO4 + Cl
HCO3 + CO3
Na + K
Na + K HCO3 + CO3 Cl

30. Classification
Ca
Mg
SO4
Ca + Mg
SO4 + Cl
HCO3 + CO3
Na + K
Na + K HCO3 + CO3 Cl
Grouping of waters on the
Piper Diagram
suggests a common
composition and origin.
Red: Ca-Mg-SO4
Yellow: Ca-Mg-Na-Cl-
SO4

31. APPLICATION

32. Schoeller Diagram
A Schoeller Diagram is a semi-logarithmic diagram of
the concentrations of the main ionic constituents in water
(SO4, HCO3, Cl, Mg, Ca, Na/K) in equivalents per million
per kg of solution (mEq/kg).
• Concentrations of each ion in each sample are represented
by points on six equally spaced lines and points are
connected by a line.
• The diagram gives absolute concentration, but the line
also gives the ratio between two ions in the same sample.

33. Schoeller Diagram

34. Key note:
Because of logarithmic scale, if a straight
line joining the two points of two ions in
one water sample is parallel to another
straight line joining the other two points of
the same two ions in another water sample,
the ratio of the ions in both analyses is
equal.

35. Studies that use Schoeller Diagram

36. cations anions
[semi-logarithmic axis]

37. Durov’s Double Triangular Diagram
Description/ Type of data : a composite plot consisting
of 2 ternary diagrams where the cations of interest are
plotted against the anions of interest (data is normalized to
100%); sides form a binary plot of total cation vs. total
anion concentrations (this plot can be contoured);
expanded version includes TDS (mg/L) and pH data
added to the sides of the binary plot to allow further
comparisons.
• Primary: Cations (i.e. Na + K, Ca and Mg) and Anions
(i.e. Cl, HCO3 and SO4), and total cations vs. total anions
only.
• Expanded: TDS and pH added

39. Applications
To graphically illustrate cation/anion concentrations, relative
to TDS and pH.
For example, using samples IC and AAS data, we can
plot the ion concentrations, then calculate the TDS
from our specific conductivity field measurements, and
use the pH field measurements. Because we sampled at
several locations (i.e. causeway, pond, etc.), we can
use those as data groups to see if there are any spatial
variations in water chemistry , and if so, could they be
related to a different TDS content, different pH, or both

40. The intersection of lines
extended from the two sample
points on the triangle to the
central rectangle gives a point
that represents the major-ion
compositions on a percentage
basis. From this point, lines
extending to the adjacent
scaled rectangles provide for
representations of the analyses
in terms of two parameters
selected from various
possibilities, such as total major-ion
concentrations, total
dissolved solids, ionic strength,
specific conductance, hardness,
total dissolved inorganic carbon,
or pH.
Durov SA, 1948, Natural waters and graphic representation of their composition

41. Collins bar Diagram
Display of concentrations (not ratios) for
individual samples
But as it is a cumulative chart the values are
not readily apparent
Total height ~ reflects TDS
Easier to compare samples than pie charts

42. Collin bar Diagram

43. Collin Bar Diagram
These are vertical bar diagrams. Each sample is
represented by two bars, one for cations and other for
anions. The height of each bar is proportional to the total
concentration of cations or anions in meql-1.
The concentration of cations and anions can be plotted
either in absolute values or as the percentage of total epm.
The Collin’s bar chart was used to show the concentration
of various major ions of the analyzed samples.
The cations are represented as Ca2+, Mg2+, Na+, K+, and
the anions as Cl-, SO2- and CO2-, HCO2- .
4
3
3

44. Gibb’s Diagram
Many aspects of the over all mechanism are still poorly
understood of Ground water. Therefore, Gibb's suggested a
graphical diagram to understand the water chemistry
relationship of the chemical components of the water
from the respective aquifers, such as chemistry of the rock
types, chemistry of the precipitated water and rate of
evaporation.
Based on Gibbs variation (ratio – I) i. e. anions dominant
and Gibbs variation (ratio – II) i. e. cation dominant nature,
the groundwater samples of the area are plotted separately
against respective values to know the nature of the
groundwater chemistry of the area .

45. Gibb’s Diagram

46. Gibb’s Diagram
The Gibbs plot depicted that the chemistry of waters were
modified by chemical weathering piloted by precipitation
as the major factor controlling the chemistry of the sub-surface
waters
It illustrates the three major mechanisms that regulate the
chemistry of the world's water:
(1) Evapo-concentration
(2) selective mineral precipitation
(3) rainfall of variable composition

47. Stuyfzand Classification
A new hydrochemical classification of water types.
This subdivides the most important chemical water
characteristics at 4 levels. The primary type is determined
based on the chloride content (Table I).
The type is determined on the basis of an index for
hardness (Table II). The classification into subtypes is
determined based on the dominant cations and anions.
Finally, the class is determined on the basis of the sum of
Na, K and Mg in meq/l, corrected for a sea salt
contribution.

48. Primary Classification (Table I)
Fresh water Class Code Chloride (mg/L)
Very oligohaline G <5
Oligohaline G 5-30
Fresh F F 30-150
Fresh-brackish f 150-300
Brackish B 300-1000
Brackish-salt b 1000 – 10,000

49. Index of Hardness (Table II)
Hardness Code Hardness (Ca+Mg)
meq/L
Very soft * 0-0.5
Soft 0 0.5-1.0
Moderately Hard 1 1-2
Hard 2 2-4
Very Hard 3 4-8
Extremely Hard 4 8-16
Extremely Hard 5 16-32
Extremely Hard 6 32-64
Extremely Hard 7 64-128
Extremely Hard 8 128-256
Extremely Hard 9 >256

50. Conclusion
It provides a quick processing and interpretation of a lot
of complete water analysis and a short, concise
presentation of the results in graphical form makes
understanding of complex. groundwater system simpler
and quicker.
This study illustrated the usefulness of multivariate
statistical techniques in the water quality assessment and
identification of pollution sources.
Accuracy assessment of the classification process using
different classification algorithms is always recommended
for the assessment of Ground water quality.

51. Conclusion
A graphical classification approach by
using geochemical analysis of the ground
water in order to estimate potential quality
of the groundwater resources.