Piper Trilinear Digram Hydrogeology.pptx

The Piper trilinear diagram is a graphical representation commonly used in hydrogeology and geochemistry to illustrate the chemistry of water samples. It helps to visualize the ion composition of different water samples and can be used to compare the relative abundance of major cations and anions. This diagram is particularly valuable for understanding the geochemical processes that influence water chemistry and for classifying water types.

### Introduction

The Piper trilinear diagram, named after Arthur M. Piper, who introduced it in 1944, is a combination of two ternary plots (one for cations and one for anions) and a central diamond-shaped plot. Each of these plots serves a specific purpose in representing the chemical composition of water samples. The cation plot displays the relative percentages of major cations, typically calcium (Ca²⁺), magnesium (Mg²⁺), and sodium plus potassium (Na⁺ + K⁺). The anion plot, on the other hand, shows the relative percentages of major anions, typically chloride (Cl⁻), sulfate (SO₄²⁻), and bicarbonate plus carbonate (HCO₃⁻ + CO₃²⁻). The central diamond-shaped plot then combines the information from the cation and anion plots to give a comprehensive overview of the water chemistry.

### Structure of the Piper Diagram

The Piper diagram consists of three main parts:
1. **Cation Triangle**: This is the lower left-hand triangle where the relative concentrations of the three major cations (Ca²⁺, Mg²⁺, and Na⁺ + K⁺) are plotted. Each apex of the triangle represents 100% of a particular cation, while the sides of the triangle represent mixtures of the cations.

2. **Anion Triangle**: This is the lower right-hand triangle where the relative concentrations of the three major anions (Cl⁻, SO₄²⁻, and HCO₃⁻ + CO₃²⁻) are plotted. Similar to the cation triangle, each apex represents 100% of a particular anion.

3. **Diamond-Shaped Plot**: The diamond-shaped plot is located above the two triangles and is derived by combining the information from the cation and anion triangles. The points plotted here represent the overall chemical composition of the water samples.

### Understanding the Cation and Anion Triangles

#### Cation Triangle

In the cation triangle, the three vertices represent 100% concentration of Ca²⁺, Mg²⁺, and (Na⁺ + K⁺) respectively. The position of a sample within this triangle indicates the relative abundance of these cations. For example, a sample located near the Ca²⁺ vertex indicates a high concentration of calcium, whereas a sample near the Mg²⁺ vertex indicates a high concentration of magnesium. If a sample is located near the center of the triangle, it suggests a more balanced mixture of the three cations.

To plot a point in the cation triangle, the relative percentages of Ca²⁺, Mg²⁺, and (Na⁺ + K⁺) are first calculated, and then the point is located accordingly within the triangle. The sum of the percentages for each sample must always equal 100%.

#### Anion Triangle

The anion triangle operates

1. GROUNDWATER PIPER DIAGRAMS

2. Piper diagrams show the relative concentrations of six to seven ions in solutions, in this case, the cations Ca, Mg, and Na+K , and the anions Cl , SO4, and HCO3. In most natural waters, these ions make up 95 to 100% of the ions in solution. The Piper diagram includes two trilinear diagrams, one for anions (on the lower right) and one for cations (on the lower left). For each sample, the information from each trilinear diagram is projected up into the central quadrilateral. Therefore, each sample will plot in each frame of the Piper, once representing cations , once representing anions, and once representing the combination. For each constituent, the concentration (in mg/l) is converted to chemical equivalents ( meq /l) based on the valence and atomic weight. Then the percentages of each ion relative to the total are calculated, and plotted on the Piper diagram. Each trilinear diagram shows the relative percentages of the three ions. Each corner on the triangles represents 100% of the ion shown at that corner.

3. The axes of the trilinear and quadralinear diagrams are read in varying directions. Cations (in the lower left) are read with values increasing clockwise along each leg of the trilinear diagram from 0% to 100% with the axis restarting at 0% at each apex of the triangle. Ca is on the bottom axis ranging from 0% on the right end to 100% on the left end of the axis. Mg is on the left leg of the trilinear diagram ranging clockwise from 0% on the bottom of the leg to 100% on the top of the trilinear diagram. Similarly, Na plus K are added together and represented on the right side of the cation trilinear and increase in a clockwise direction. Anions in the lower right trilinear are read in a counter-clockwise direction along each axis in a similar fashion. In this case, Cl is represented along the bottom leg, SO4 along the right leg, and HCO3 along the left leg of the trilinear diagram. The location of the datapoint in each of the trilinear diagrams is then projected up into the quadrilateral, and plotted where the two projections intersect. The upper right side of the quadrilateral diagram is the sum of Ca plus Mg. The upper left side is the sum of Cl plus SO4.

4. An example of a Piper diagram is shown below. The sample represented by the black triangle contains 100% Cl for anions; 60% Na+K , 40% Ca and 0% Mg for cations . The sample represented by the red triangle contains approximately 30% Cl , 40% SO4, and 30% HCO3; 25% Ca, 30% Mg, and 45% Na+K . Note that the Piper diagram shows relative concentrations only, because the concentrations are shown on a percentage basis. No information about absolute concentrations is shown on this type of Piper diagram.

5. mg/L = meq /L × Equivalent Weight CONVERSION

6. STIFF PATTERN

7. Aim of the Experiment: Plot the chemical analysis of water sample in Trilinear diagram and represent its Stiff Pattern