According to geological, hydrogeological, geophysical, hydrogeochemical, isotope and other investigations, carried out in the Borjomi-Bakuriani test area, we conclude that the waters of rivers Borjomula and Gudjaretis-tskali are formed simultaneously in the same recharge area, namely, Bakuriani-Tsikhisjvari lava plateau. After infiltration in lava sheet, "spring water" flows along ancient river valley in Quaternary alluvial and dicharges as Sadgeri and Daba springs. This is confirmed by isotope data- the stable isotope data presented above reveal that Sadgeri spring which supplies the Borjomi resort with potable water, as well as Daba springs, carry essentially fresh water, isotopically and chemically similar to that of Borjomula river and Tba borehole drilled in the lava bed. Stable isotope data also suggest that all springs mentioned above contain additional water component, recharged at higher elevation, with longer mean transit time to the discharge points. This hypothesis is supported by significantly lower tritium content in springs compared to rivers.
Water flows along breccia rocks and that is why their pathway to surface is longer than the route of waters flowing to rivers. This is confirmed by chemical data- the springs' waters are richer in magnesium than river waters. By monitoring data, maximum of season variation in the Daba spring is fixed later (30-40 days) then in river Mtkvari. It means that the pathway of water from recharge area to springdischarge area is longer then pathway to the river. Hydrodynamic modelling reveals the difference between durations of water flow for above two pathways, equal from 70 to 30 days. Thus the possibility of Borjomi city drinking water pollution in case of pipeline accident is very possible, and realistic. In this connexion, it is necessary to take effective measures for protection of water source areas.
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