Erratum to: Aquifer vulnerability and groundwater quality in mega cities: case of the Mexico Basin

Erratum to: Environ Earth Sci DOI 10.1007/s12665-009-0434-5

The original version of this article unfortunately contained some mistakes. The presentation of Eqs. 6 and 7 was incorrect. The correct versions are given below.

$$ \text{WQI} = k{\frac{{\sum {C_{i} P_{i} } }}{{\sum {P_{i} } }}} $$

(6)

$$ \text{CI} = \sum\limits_{i = 1}^{n} {C_{{\text{f}}i} } $$

(7)

The last sentence of paragraph “Defining parameters for SINTACS” should read “WQI indices range from 0 to 100, and some authors have defined quality scales as indicated in Table 4”.

In the tablehead of Table 4, it should read “WQI scale” instead of “ICA scale”.