Divalent ion chemistry as an indicator of groundwater flow type through the carbonate aquifer in el-Arish – Rafah area

الملخص EN

The main object of this work is to study the chemistry of groundwater hardness in the carbonate aquifer in EL Arish- Rafah area and its relationship with the groundwater flow type.

Generally, the water chemistry including the salinity, hardness (total, temporary and permanent) and the controlling factors affecting them (leaching, dissolution, CO2, water pH, temperature and ion exchange processes) were studied in details.

The study revealed that the total hardness of the continental kurkar groundwater is generally less than that of marine kurkar groundwater.

The groundwater hardness in the continental kurkar aquifer is more temporary than that of permanent hardness and vice versa in case of the marine kurkar aquifer.

The effect of leaching, dissolution, longer residence time in continental and old marine sediments, CO2, alkaline pH (7-9).

Water temperature and action exchange leads to an increase of total hardness compared to the marine faces groundwater types more than that of the continental faces.

Also, the permanent hardness of marine faces groundwater types exceeds permanent hardness of the continental faces and the reverse is true in case of temporary hardness.

The variation coefficient of hardness has been used to detect the mode of water circulation within the carbonate aquifer.

The high temporal variation coefficient of groundwater hardness of continental kurkar aquifer at EL–Sheikh Zewied–Rafah coast and marine kurkar at the southern parts, indicates fast flowing system.

On the other hand, the low temporal variation coefficient of groundwater hardness of continental kurkar aquifer at South Rafah inland and marine kurkar of west EL-Kharouba indicates slow flowing system.

These results are also confirmed by determination of the velocity groundwater movement from the hydraulic parameters of both continental and marine kurkar aquifers.

Another trial was performed by using the variation in total hardness relative to salinity (TH / TDS).

The obtained data follow the same pattern obtained by variation in total hardness.