الخصائص الهيد وكيمائية و درجة التحلل الكارستي في نبع غين الفيجة : سوريا

الملخص EN

Though it is quite difficult to deal in a comprehensive manner with all aspects of the ka؟stgic activity and its geomorphological manifestation in the limited space of a single !■esearch paper؛ yet an attempt has been made in this study to expose the meagre extent of the velocity and magnitude of the karstic corrosion in Ain A1 Fijah Karstic spring which supplies Damascus with water and also feeds the Barada River.

The study will also aim to examine the ineffectiveness of the Karstic corrosion in explaining the presence of both internal and external features.

Such features as ^piez, Dolines and Ouvalas have developed and spread over the versant basin, the catchment area for Ain AL-Fijah.

The Ineffectiveness of the corrosion is, definitely, attributed on one hand to the lack of a dense vegetational cover over the basin that would have been able to provide the organic acids badly needed for the Karstic activity.

It is also owed, on the other hand, to the ever inereasing joint effect of the relative decline of the precipitation values that record only 497 mm per annum and the relative increase of temperature that reacheds an annual average of 13,2°c which consequently causes higher rates of evaporation reaching 428,3 mm per annum and results in a net precipitation value of 68,5 mm annually.

Building on all that it is safe to surmise that the emergence and development of those Karstic features, with no doubt, date back to intervals between the four glacial periods, however the early appearance of their internal stages could be traced down to the latter part of the Tertiary.

This fact could will be explained by the present slow rate of the Karstic corrosion of 3,96 mm/1000 years, a rate that does not allow the emergence of the younger Karstic features such as Lapiaz due to its limited magnitude.

The spring water not only loses all its energy while running underground to dissolve the carbonic rocks; but also as evident the chemical mathematics, that it is a saturated water