An attempt was made to understand how surface-groundwater interaction and impact both water quality and quantity in the area between El-Timsah Lake and Ismailia Canal, Egypt. Twenty one surface and groundwater samples were collected from the study area. Hydrochemical data revealed that total dissolved solid (TDS) of Ismailia Canal and groundwater samples ranged from 328 to 613 and 345.7-1099 mg/l respectively. Salinity of El-Timsah Lake samples ranged from 16730 to 34560 mg/l. The lowest salinity was existed in the middle and western edge of the lake which indicates the discharge of Ismailia Canal and drainage water into the lake. According to drinking water quality index (DWQI), most of groundwater is suitable for drinking purposes, but some wells in the study area were threatened due to increasing salinity. Highest values of nitrate and phosphate concentration in groundwater reached 53.4 and 1.8 mg/l respectively which are slightly above permissible limits. Also, the concentrations of trace elements (Al, B, Fe, Mn, pb, Mo, Si and Sr) in some surface and groundwater samples exceeded the international standard limits. The increase of nitrate, phosphate and some trace elements concentration may be fed rapid pollution path to the underlying, shallow aquifers which may have impact on groundwater quality. Stable isotopes(δ 18 O and δ 2 H) of groundwater samples ranged from 2.54 to 3.39‰ and 22.95 to 27.79‰ respectively. The isotopic content (δ 18 O and δD) of groundwater is similar to the isotopic content value of the recent Nile water and Ismailia Canal. This confirms that Ismailia Canal and drainage water are considered a recharge source for the unconfined aquifer.

The present work is devoted to determine sources of groundwater salinity and suitability of its use for irrigation and drinking in northwest ElMinia, Upper Egypt. This information is important for sustainable and reliable development of the groundwater resources. A hydrochemical study using results of major ions and trace elements analysis of 43 groundwater samples collected from the study area have been conducted in this work. The TDS and major ionic concentrations vary in considerably wide ranges, these increase westward and northward under effect of rock minerals dissolution and upward leakage of saline water. The water types, ionic orders, hypothetical salts combination , multivariate analysis and ions / ions relations reflect a high stage of salinity development with (SO4 2-, Cl-/Na + , Ca 2+) hydrochemical facies in 80% of the samples, the rest (20%) are less developed with higher HCO3 on expense of SO4. The groundwater salinity in the study area is developed under effects of rock minerals dissolution (halite, calcite, dolomite, and gypsum), cation exchange and mixing waters between aquifers. The hazards of increasing salinity and major ions / trace elements toxicity for groundwater use in irrigation and drinking have been evaluated using hydrochemical indexes and standard classifications.

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The northeastern part of Greater Cairo is a target for development and anthropogenic activities

The natural attenuation capacity of groundwater is considered to be an important factor for remediation purpose, it is also important for surveying suitability in the early phases of siting hazardous facilities. The present work has been devoted to explore the natural attenuation capacity of the groundwater system northeast Cairo. Some indicators (hydrogeological, hydrochemical and isotopic) have been insighted to explore the system retardability against contaminant dispersion. Groundwater flow and contaminant transport have been pointed out using GOD index which varied from 0.04 to 0.28 reflecting high protectability. The isotopic contents (18O, 3H, and 14C) showed a general comply with the GOD index and helped to delineate the sectors of high contaminate attenuation ability. Kelly index inferred significantly high adsorption potential on the aquifer clay content. The calcite and dolomite tend to precipitate on the aquifer contact providing a chance for specific contaminants to co-precipitate. The Eh-pH relation of the studied groundwater samples indicates high oxidation conditions and openness of the system. The attenuation capacity has been determined mathematically, it assumes the dispersive, advective, sorptive, and degradative processes acting on a solute in a one-dimensional flow system. The value of attenuation capacity increases by decreasing groundwater velocity and completely vanishes at a certain high velocity; determined for the relevant radioactive contaminants.