Hydrochemistry of the groundwater resources in the northeastern part of Mafraq area, Jordan

الملخص EN

This study deals with water quality and salinization of the upper aquifer complex in NE part of Marfaq area.

The aquifer is composed of Tertiary age and silicified limestone rock unit of Upper Cretaceous age.

The studied area is characterized by the presence of intensive agricultural activity and low annual rainfall (150-200 mm).

Due to these facts groundwater is intensively exploited for irrigation purposes whereas almost two folds of the groundwater safe yield (38 MCM/year) is extracted from the aquifer.

During the last two decades more than 5000 water samples were collected and complete chemical analysis for the major cations and anions were carried out on these samples from various wells by the Ministry of Water and Irrigation and the University of Jordan.

The results were subjected to different statistical and hydro chemical evaluations in this research.

They revealed the fact that the salinity of the water has been increased from 300 µS/cm in most of the areas under investigation during early seventies to more than 8000 µS/cm in certain localities.

Similar trends of increase were also recognized for Na, Ca, Mg, K, Cl, SO4 and NO3 ions.

The increase in concentration of the ions (except nitrate) is attributed to leaching processes of the intensively furrow irrigated soils.

The increase in the nitrate concentration from 10 mg/L during the same period to 90 mg/L is believed to be due to the leaching of fertilizers (chemical and organic) which are intensively used in the area.