Grupo

Índice

Ecuación/Descripción

Indicators

1

NSF-WQI (EU)

(Brown et al. 1970)

$\text{NSF-WQI}={\displaystyle \sum _{i=1}^{9}S{I}_i\ast W_i}$

SNF-WQI: Water quality index according to the U.S. National Sanitation Foundation; a number between 0 and 100

SI_i: Quality of the i-th parameter. A number between 0 and 100; depending on concentration or measurement (analysis result).

W_i: Weight corresponding to the i-th parameter set according to its importance for the overall conformation of quality; it is a number between 0 and 1.

Temperature, pH, dissolved oxygen, biological oxygen demand, turbidity, total solids, faecal coliforms, nitrates and total phosphates

Dinius-WQI (EU)

(Dinius 1987)

$I={\displaystyle \sum _{i=1}^{11}{W}_i\ast I_i}$

I_i: Variable sub-index

W_i: Weighted weight for sub-index i.

Temperature, pH, dissolved oxygen, biological oxygen demand, nitrates, colour, conductivity, alkalinity, hardness, chlorides, total coliforms and faecal coliforms.

CETESB-WQI (Brasil)

Rojas-WQI

(Colombia)

$\text{WQI}={\displaystyle \prod _{i=1}^n{I}_i{}^{W_i}}$

W_i: Weight or percentage assigned to the i-th parameter

I_i: Sub-index of i-th parameter.

Temperature, pH, dissolved oxygen, biological oxygen demand, turbidity, dissolved total solids, faecal coliforms, total phosphorus and total nitrogen.

CCME-WQI (Canadá)

DWQI (EU)

$\text{CCMEWQI}=100-\left[\frac{\sqrt{{\left(F_1\right)}^2+{\left(F_2\right)}^2+{\left(F_3\right)}^2}}{1.732}\right]$

Scope (F₁): Percentage of parameters that exceed the standard.

Frequency (F₂): Percentage of individual tests for each parameter that exceeds the standard.

Amplitude (F₃): magnitude by which each parameter that does not comply exceeds the norm.

F₁

F₂

F₃

3

U-WQI (Europa)

(Boyacioglu 2007)

$\text{UWQI}={\displaystyle \sum _{i=1}^n{W}_i{I}_i}$

W_i: weight or percentage assigned to the i-th parameter

I_i: i-th parameter sub-index.

Cadmium, cyanide, mercury, selenium, arsenic, fluoride, nitrate-nitrogen, DO, BOD₅, total phosphorus, pH and total coliform.