Graphical presentation and classification for assessment of Ground water Quality by ISM Ravi Kiran JP
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The document discusses various graphical techniques for presenting and classifying groundwater quality, emphasizing the significance of understanding hydrogeological systems and groundwater contamination. It highlights methods such as Stiff diagrams, Piper diagrams, and Schoeller diagrams for visualizing complex chemical data, facilitating easier comparison and assessment of water quality. Additionally, the paper emphasizes the importance of graphical analysis for managing groundwater resources and detecting pollution sources.
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Graphical presentation and classification for assessment of Ground water Quality by ISM Ravi Kiran JP
- 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.
- 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
- 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.
- 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
- 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.