Formulas

Percentage of sodium

$\%\text{Na}={\text{Na}}^{+}+{\text{K}}^{+}/\left({\text{Ca}}^{2+}+{\text{Mg}}^{2+}+{\text{Na}}^{+}+{\text{K}}^{+}\right)\ast 100$

Equation (1)

Sodium absorption ratio

$\text{SAR}={\text{Na}}^{+}/\left[\left({\text{Ca}}^{2+}+{\text{Mg}}^{2+}\right)/\text{2}\right]$

Equation (2)

Magnesium absorption ratio

$\text{MAR}\left(\text{meq}/\text{l}\right)=\frac{{\text{Mg}}^{2+}}{{\text{Ca}}^{2+}+{\text{Mg}}^{2+}}\ast 100$

Equation (3)

Residuel sodium carbonate

$\text{RSC}\left(\text{meq}/\text{l}\right)=\left({\text{CO}}_{\text{3}}^{\text{2+}}+{\text{HCO}}_3^{-}\right)-\left({\text{Ca}}^{2+}+{\text{Mg}}^{2+}\right)$

Equation (4)

Kelly’s Ratio

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

Equation (5)

Corrosivity Ration

$\text{CR}\left(\text{mg}/\text{L}\right)=\frac{\frac{{\text{Cl}}^{-}}{35.5}+2\ast \frac{{\text{SO}}_4^{2-}}{96}}{2\frac{{\text{HCO}}_3^{-}+{\text{CO}}_3^{2-}}{100}}$

Equation (6)

Permeabillity index

$\text{IP}=\left[\left({\text{Na}}^{+}+{\text{HCO}}_3^{-}\right)/\left({\text{Ca}}^{2+}+{\text{Mg}}^{2+}+{\text{Na}}^{+}\right)\right]$

Equation (7)