The CCME WQI has been calculated and compared with the classification of WQIs, Table 9, to evaluate the suitability of the studied groundwater for drinking purposes. A water quality map has been created using GIS, as shown in Figure 5, showing that the groundwater quality of the study area falls in two categories:
‘Fair’ (CCME WQI values range from 65 to 79) for all the Miocene aquifer groundwater samples, which could be attributed to the high salinity values of old marine deposits of this aquifer. Also this category has been noticed in some Quaternary groundwater samples as a result of over-pumping activities.
‘Good’ in Quaternary aquifers (CCME WQI values from 80 to 94), this highlighting the presence of an eastern recharge front from the Nile to the Quaternary aquifer direct recharge source and reflecting the high renewability of this aquifer.
Figure 5
Groundwater quality map for the study area using Super GIS.
Table 9
Categorization of the WQI CCME Method (Canadian Council of Ministers of the Environment 2001)
| Categorization | Index value | Water quality |
|---|---|---|
| Excellent | 95–100 | Virtual absence of threat or impairment |
| Good | 80–94 | Minor degree of threat or impairment |
| Fair | 65–79 | Occasionally threatened or impaired |
| Marginal | 45–64 | Frequently threatened or impaired |
| Poor | 0–44 | Almost always threatened or impaired |
| Categorization | Index value | Water quality |
|---|---|---|
| Excellent | 95–100 | Virtual absence of threat or impairment |
| Good | 80–94 | Minor degree of threat or impairment |
| Fair | 65–79 | Occasionally threatened or impaired |
| Marginal | 45–64 | Frequently threatened or impaired |
| Poor | 0–44 | Almost always threatened or impaired |