Formula

Reference

Percentage of Sodium

$\%\text{Na}=\frac{{\text{Na}}^{+}+{\text{K}}^{+}}{{\text{Na}}^{+}+{\text{K}}^{+}+{\text{Ca}}^{2+}+{\text{Mg}}^{2+}}\times 100$

[15]

Kelly’s Ratio

$\text{KR}=\frac{{\text{Na}}^{+}}{{\text{Ca}}^{2+}+{\text{Mg}}^{2+}}$

[16]

Magnesium Adsorption Ratio

$\text{MAR}=\left(\frac{{\text{Mg}}^{2+}}{{\text{Mg}}^{2+}+{\text{Ca}}^{2+}}\right)\times 100$

[17]

Total Hardness

$\text{TH}\left({\text{CaCO}}_3\right)\text{mg}/\text{L}=2.5{\text{Ca}}^{2+}+4.1{\text{Mg}}^{2+}$

[18]

Residual Sodium Carbonate

$\text{RSC}=\left({\text{CO}}_3+{\text{HCO}}_3-\left(\text{Ca}+\text{Mg}\right)\right)$

[19]

Sodium Adsorption Ratio

$\text{SAR}=\frac{\text{Na}}{\sqrt{\frac{\text{Ca}+\text{Mg}}{2}}}$

[20]

Permeability Index

$\text{PI}=\frac{\left(\left(\text{Na}+\text{K}\right)+\sqrt{{\text{HCO}}_3}\right)\times 100}{\text{Ca}+\text{Mg}+\text{Na}+\text{K}}$

[21] [25]

Water Quality Index

$\text{WQI}={\displaystyle \sum _{i=1}^n{W}_i{q}_i}{\left[{\displaystyle \sum _{i=1}^n{W}_i}\right]}^{-1}$

[22]