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Hydrological Peculiarities of the Kura River Basin


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Introduction
Despite the abundance of water resources in whole in Georgia, significant negative economic changes (destabilization) are emerging in the catchment area of the Kura River due to the constantly increasing loads to the river system.
As known, ecological destabilization has an effect not only on the internal policy of the country, but also on international relations, as it infringes the interests, sometimes vital, of neighbouring countries. The Kura River basin encompasses rather large areas of four states – Turkey, Armenia, Georgia and Azerbaijan (Armenia is completely in this basin), and, hence, solution of water problems of the Kura River becomes of international importance. Without any doubt, due to constantly aggravation of negative effects of ecological changes, solution of the issue of ecological destabilization is becoming urgent.
At present the issue of the reconsideration of water economy policy of the country is acute (critical), the basis of which should become the complex use of surface and ground water resources envisaging, along others, both strong control of water intake and transition to water use management. With the purpose of geological and hydro-geological substantiation of such a scheme complete survey of surface and ground waters is necessary. Below is given a general description of hydro-geological conditions of the Kura Basin which should serve as a basis for the assessment of its resources.


Hydrological Peculiarities of the Kura River Basin

According to the geological structure and geo-morphological and hydro-geological conditions in the Eastern Georgia within the basin of the Kura River the following first priority hydro-geological regions of ground-water are distinguished:



  1. The pressure-water systems of the Greater Caucasus;

  2. Artesian basins of eastern submergence of Trans-Caucasian intermountain trough or the Kura artesian basin;




  1. The pressure-water systems, ad-artesian basins and hydro-geological bodies of the Lesser Caucasus

Within the pressure-water systems of the Greater Caucasus are distinguished the following second priority hydro-geological areas: Kazbegi-Mtatusheti (I1) and Mestia-Tianeti (I2) pressure-water systems and the area of interstitial water of Keli-Kazbegi lava flows (I3).


Within the Kura artesian basin the following artesian basins are distinguished: Kartli (II1), Alazani (II2) and Iori-Shiraki (II3) artesian basins.
Within the territory of the Lesse Caucasus are distinguished Akhaltsikhe (III1), Tbilisi (III3), Marneuli-Gardabani (III4) ad-artesian basins, Trialeti pressure-water system (III2) and Samtskhe-Djavakheti (III5) hydro-geological bodies (Fig. 1).
Intensive development of exogenous and tectonic fissuring, porosity, facies-lithologic diversity of rocks, intense rugosity, plicate (folded) and breaking (discontinuous) tectonics – all this taken together condition the richness of ground-water resources and heterogeneity water-bearing horizons and complexes distinguished by individual hydro-dynamic features and mineralization peculiarities and chemical composition of ground-waters.
Particularly important role in the accumulation and movement of ground waters play the tectonic structure and geo-morphological conditions – synclinal feature, interchange of non-watertight and retainer (water-proof) rocks, high hypsometric position of supply (feeding) areas condition wide spread of pressure water-supply horizons and complexes within the artesian basins.
Disjunctive (Alternative) transgressions, splitting the whole thickness of sedimentary deposits, in its turn, contribute to the movement of ground waters from the deep horizons into the upper ones, being favourable to hydro-geological connection (link) between them, conditioning hydro-chemical and geo-thermal anomalies in the upper floors of hydro-geological section.

Description of Main Horizons and Complexes
1.1. Water-bearing horizon of contemporary (present-day, new) alluvial sediments are developed in the vallies of the Kura River and its big tributaries: Liakhvi, Ksani, Aragvi, Alazani, Iori, Khrami and others. It is composed of pebbles with the sandy and sandy-uliginous filler with the layers and sand lenses, clay sand, loams and clay, encompassing flood-lands and above flood-lands river terraces. Horizon capacity varies, mainly within 3-10, seldom reaching 15 meters. Filtration coefficient (factor) amounts to 10-100, more rarely to 200-500 m/24 h.
The horizon is fed with the rivers water and at the same time, being unloaded into river, consequently – the waters of the horizon are in the hydraulic relation with the rivers waters. Water-bearing horizon is rich in water, while the water of the horizon is of high drinking quality.
On the basis of the ground waters of this horizon big water intakes of centralised economy and drinking water supply for Tbilisi and Mtskheta (on the Aragvi and Ksani rivers) Gori (on the Liakhvi river) Akhaltsikhe and Khashuri (on the Kura river) Telavi and Gurjaani (on the Alazani river), Sagaredjo and Tianeti (on the Iori river), Marneuli (on the Khrami river) and other settled areas have been constructed.
Operating (Operational) supply of the horizon varies (fluctuates) mainly within 0,2-3,0 m3/sec. Particularly large deposits (Bulachauri, Misaktsieli, Natakhtari, Saguramo) with the overall operational supplies up to 10 m3/sec., belong to the Aragvi river valley (table 12).
Underground waters are characterised with good drinking quality, low mineralization (0,3 – 0,65 g/l), hydrocarbon-calcium content; total hardness – 3-4 mg/equiv, temperature – 12-160C, pH – 6,8-7,0.
1.2. Water-bearing horizon of old quaternary alluvial and proluvial sediments is particularly widely spread within Tirifino-Mukhrani, Marneuli-Gardabani, Alazani valleys and the Iori plateau – Iori valley. The horizon is comprised of boulder pebbles, mellow (porous) conglomerates, shingle, sand, clay sand, and loam. The horizon capacity is 10-500 m.

Within the area of Tifino-Mukhrani valley – Kartli artesian basin – the water-bearing horizon is represented mainly by mellow (porous) conglomerates in the lower part of the section and pebbles with the clay and loam layers – in the upper one. Similar situation is observed in Mukhrani valley.


Because of Igoeti and Kartalini elevations the under-ground waters of the horizon are devided into two flows – Tirifino-Saltvi and Mukhrani ones. In the northern strip of the valley the Bazaleti and Ertsoi troughs form independent basins of underground waters with comparatively small capacity.
Ground waters - filtrates of the main water-way of the Kura river tributaries from the left side – after the debouchments (outflow from the gorge) overflow the depression bottom comprising of the low-penetrating conglomerates of myo-pliocene age forming high-capacity ground-water flows. In the northern part of the valley the groundwater surface sharply declines southwards, depositing at the depth of 10-25 meters below the soil surface. Still southwards, in parallel with the plateauing, pebbles are replaced in facies with clay and loam and downstream horizons of ground waters are formed being discharged (unloaded) southwards of the axial line of the depression in the form of high-capacity Degot-Urbnis-Bebnis, Mukhrani-Natakhtari group sources with the total debit over 3, 0 m3/sec.
Particularly should be stressed the presence of trough-shaped reservoir of ground-water downstream waters situated within the Mukhrani depression area and containing high quality drinking water with approximate statistical operating supplies up to 2 billion cubic meters. Mineralization of the waters varies between 0, 2-0, 3 g/l, temperature – 9-110C.
Within the area of Kartli artesian basin in the water-bearing horizon at the depth of 50-250 meters boreholes (wells) of downstream sub-artesian waters with the piezometric (pressure gradient) level from – 12 to + 10 meters have been bored.
Chemical content of the water predominantly is hydro-carbonate, calcium and sodium with the mineralization up to 1 g/l.
Old Quaternary alluvial and proluvial deposits are mostly spread in the Alazani valley within the area of the Alazani artesian basin. Here the formations of debris cones of the Alazani river tributaries make (compose) high-capacity water-bearing layer (30-500 meters) on the both banks of the river, particularly large-scale being on the left embankment and the central part of the valley (fig. 2, 3).
Presence in the section of these sediments with the facial replacing each other water-proof and non-water-tight layers create conditions for the formation of hydraulically inter-related water-bearing strata. At the tops of debris cones, mainly in the left inflows of the Alazani River, where the river water and atmospheric precipitation is intensively absorbed, ground waters lie down at the depth of 10 to 60 meters. As moving the one (single) flow of ground waters become divided forming several downstream strata, however, as a whole – one so called Kvareli water-bearing horizon.
This horizon, containing about 11 water-bearing strata (layers) with the total capacity up to 90 meters, is observed, mainly along the left bank of the Alazani river and partially getting across to the right bank, lying down to the depth of 5 to 200 meters.
The debit of self flowing wells varies from 0, 2 to 165 l/sec, specific debit – 0, 1-5 l/sec, debit factor (coefficient) of water conductivity – 500-1500 m2/24 h.

Chemical water contain is hydrocarbon-sulphate-calcium-magnesium; hydrocarbon-calcium-magnesium and sodium-calcium. Mineralization here equals 0, 2-1, 0 g/l, hardness – 1, 8-6, 5 mg/equiv, temperature – 13-16,50C, pH – 6, 5-7, 2.


The basic feeding area of Kvareli horizon is situated along the foothills of the South slope of the Main Caucasus ridge and encompasses the tops (peaks, crests) of debris cones of the Alazani River left inflows.
Feeding sources of this horizon are rivers (8, 8 m3/sec), fissure and karst inflow from the southern slope of the Big Caucasus ridge, atmospheric precipitation, (3,1 m3/sec) and downstream waters underlying Apsheron-Akchagil deposits. For the assessment of the amount of feeding resources at the expense of the inflow of fissure and karst and downstream waters of the Apsheron-Akchagil deposits, it is necessary to undertake special testing and hydro-geological and thematic work.
Within the horizon two zones of the ground water movement are distinguished: 1) zone of active movement – the area of supply characterised by sharp decrease of piezometric level of water (inclination – from 0, 006 to 0,15) and 2) zone of slow movement, occupying the central part of the basin with the inclination of the ground water surface – 0, 0001.
The area of Kvareli water-bearing horizon unloading is located in the Alazani river valley. The horizon is unloaded into the ground water through the hydro-geological openings and relatively waterproof roofing at the expense of excess pressure. This causes, on the one hand, swamping of rather big territories, and on the other – soil salination at the right bank of the Alazani river (area of Milari steppe (fig. 2) at the border with Azerbaijan.
The amount of drained water of the Alazani river equals 14 m3/sec. For the assessment of the amount of water unloaded due to the excess pressure to the direction of Azerbaijan, it is necessary that special filtration testing and thematic work is carried out.
Operational resources of ground waters of Kvareli water-bearing horizon amount to 29, 46 m3/sec. Particularly, it should be mentioned that at the boarder with Azerbaijan within the area of the right bank of the Alazani river to the depth of 50 meters the ground water of this water-bearing horizon is mineralised, with the content of salts mostly over 1, 0 g/l and, thus, useless for industrial and drinking purposes. At the same time, mineralization is increasing upstream along the strip and reaches 30-35 g/l.. Chemically, the waters mostly contain chloride sodium-magnesium.
Old quaternary alluvial-proluvial sediments are widely spread also within Iori-Shiraki artesian basin in the region of Sagaredjo-Mtsvane Mindori (left bank of the Iori river).
Here within the debris cones of the Iori tributaries (Sagaredjos Khevi and Lakbe rivers) power (capacity) of pebbles with the sandy and sandy clay filler and sands reaches 100 meters.
Within the debris cones of the Sagaredjos-Khevi old quaternary alluvial and proluvial sediments are filling up the synclinal structure, the axis of which extends along the right-bank of the Iori river almost in parallel with the river-bed. They are rather abundant in water.
In the upper part of the debris cone proluvial sediments are represented by pebbles characterised with high water permeability. This is the main part of the area of ground waters feeding at the expense of precipitations and absorption of river water. Ground waters here have free surface. In the same area the main intake facility of economic and drinking water supply of Sagaredjo city is situated.
To the southwards comes the zone within which occurs gradual facial replacement of boulder-pebble sediments by sandy filler and pebbles with loamy and sand-loamy filler by clay. Thanks to this the water acquires pressure and there occurs their partial unloading in the form of group ascending springs here and there causing the soil swamping. With the help of wells it has been defined that in this strip the capacity of the described horizon varies within 37 and 72 meters, the average capacity amounting to 61,5. The waters are mainly self-emitting with the debit from 1,5 to 8,5 and specific debit from 1,5 to 13,0 l/sec. Average water conductivity value – 270 m2/24 h, filtration factor – 3,9 m/24 h, average gradient of piezometric surface – 0,01, using (operational) resources – 27950 m3/24 h, piezometric level – from minus 3 to +4 m.
Chemical contents of the horizon waters include hydrocarbon-calcium-sodium. Mineralization does not exceed 0, 7 g/l; common hardness – 1, 8-6, 5 mg/equiv., temperature – 13-140C, pH – 6, 8-7, 1. The water is suitable for economic and drinking purposes.
The horizon under the consideration is widely spread also within Marneuli-Gardabani valley, as well as in its peripheral parts and in all places is represented by weakly (feebly) sintered conglomerates with the lenses of loam and pebbles. They mainly compose plinth terraces and are characterised by rather weak sporadic watering.
In the central, submerged part of the valley in these sediments at the depth of 20 meters are circulating rather powerful Tamari, Gardabani, Kodi, Tselaskuri flows of ground waters with the total natural resources amounting to 36 802 m3/24 h. The most powerful out of them are Tselaskuri and Gardabani flows with the debit of 7242 and 25258 m3/24 h respectively.
By chemical composition the waters are hydro-carbon-sulphate and sulphate-hydro carbonic calcic with the mineralization up to 1, 0 g/l and total hardness 7-10 mg/equiv. The least mineralization (0,3-0,4 g/l) is observed in Tamari flow which is fed by the Khrami river.
1.3. Water-bearing horizon of middle-quaternary- upper-Pliocene lava cover is widely spread mainly within Samtskhe-Djavakheti volcanic plateau – hydro-geological body of interstitial waters. It is represented by dolerites, basalt, andesite, dacites; in the upper part – by interlayer and lenses of lake sands, clay sand and clay, and mellow (porous) tufa formations between the cover, and volcanic ashes. Capacity of these sediments exceeds 1000 meters. They are developed on small areas also within The Greater Caucasus at the upper reaches of the rivers Terek, Aragvi and Liakhvi, while min Adjara-Trialeti – in the canyons of the rivers Gujaretis-tskali and Borjomula.
Lava layers are characterised by high fissuring cooling and weathering, here and there being tectonic which conditions its abundance in water. Atmospheric precipitation (600-1000 mm per year) and favourable morphological conditions for leakage and condensation contribute to this as well, particularly at the central strips of lava flow.
Manifestation of ground waters at the surface of the plateau is insignificant. Powerful interstitial sources (particularly – formation) are belonging to the cornices of canyon-type gorges or to the contacts of outcrop relatively waterproof formations. The following sources belong to the last: Bejano with the debit of 390 l/sec, Ablari – 924, Ikhtila – 440, Ozni – 1085, Dashbash – 3760 l/sec and others. High debits of these sources and their stable regimes within Djavakheti plateau are conditioned by the presence of underground reservoirs of significant size, by all means playing the regulating role.
In the eastern part of Tsalki depression so called Beden lava stream goes descends towards Marneuli valley of the Khrami river occupying its middle course. Here this andesite-basalt stream submerges under the quaternary alluvial-prolluvial sediments and forms two downstream layers with the significant debit of interstitial ground waters.

Lava areas of the Kels Plateau-Kazbegi descending as far as 10-12 kilometres along the gorges of the rivers Terek, Ksani, Aragvi and Liakhvi, in the contact with underlying waterproof shale clay of Jurassic age are forming the outlet of big sources (Gudarekhi, Khorisari) with the debit of several hundred of litters per second.


Lava formations of the gorges of the Borjomula and Gujaretis-tskali, originating in Bakuriani-Gudjareti area, are stretched along 20-25 kilometres and are deposited on the old quaternary alluvial sediments having the capacity up to 100 m. To these streams are belonging big interstitial sources – so called “Melnichni” and many others.
The water contains hydrocarbon-sulphate sodium-calcium with the mineralization equaling 0,2-1,0 g/l,. Total hardness does not exceed 0, 5-2, 5 mg/equiv. Only Marneuli valley downstream water is characterised with the mineralization up to 1 g/l with sulphate-hydro-carbon-calcium-sodium composition under the common hardness up to 12 mg/equiv.
Natural resources of ground waters of the given horizon are extremely big. In particular, within Samtskhe-Djavakheti hydro-geological body they reach 34, 5 m3/sec, in the area of Kelski plateau – 3, and in Gugjareti-Bakuriani stream equal 0, 2-0, 3 m3/sec.
Taking into consideration geological, structural, geo-morphological conditions and the character of the formation of surface and underground flow, it is not excluded that in the areas near the borders of Armenia and Turkey ground waters spill over to the direction of the territories of these countries. According to our predicted assessment in the area of the lake Madatap the underground spillage over to the direction of Armenia amounts approximately to 0,4 m3/sec, while in the area of the lake Khozapin this occurs to the direction of Turkey coming to 1,5 m3/sec. Nevertheless, this issue requires special study - our opinion is that more detailed study of formation of hydro-geological conditions of the Samtskhe-Djavakheti hydro-geological ground water resources should be carried out, since this body is very promising with regard to the presence of high quality fresh drinking waters at the same time being the biggest hydro-geological structure at the border
1.4. Water-bearing complex Apsheron-Akchagil continental sediments is represented by the interchange of conglomerates, pebbles, sands and loam with the common capacity up to 2000 m. They are particularly largely spread in Alazani valley getting widely revealed on the northern slope of the Kakheti range. Here Telavi and Gurdjaani water-bearing horizons are distinguished (fig. 2, 3).
Telavi water-bearing horizon becomes revealed from Kogoto to the village of Red Sabatlo over 150 km. It contains about six water-bearing layers with the total capacity up to 50 m. The horizon is formed from coarse-grained sand and fine pebbles with the sandy filler. Water conductivity fluctuates within 100-200 m2/24 h.
The horizon is deposited at the depth from 90 to 360 m, gradually submerging towards north-east and south-east directions, to the central part of Alazani valley. Wells disclosing water-bearing layers of this horizon, are characterised with highly excess pressure (plus 15-25 m) and debits exceeding 1,0 l/sec. Debits from 10 to 60 l/sec are not rare here. Specific debits fluctuate within 0, 14-2, 2 l/sec under the decrease of piezometric level by 50-60 m. The radius of influence equals 700-800 meters.
Chemically the water of the given horizon comprises of hydro-carbon calcium and magnesium with the 0, 3-0, 6 g/l mineralization. In the area of the horizon the submerging mineralization increases to 4 g/l which is caused by the increase of sulphate and, even, chlorine-ion. Hardness is within 1, 0-10, 5 mg/equiv., water temperature is 12-170C.
Gurdjaani water-bearing horizon belongs to the upper part of the middle section of the Alazani. It submerges at the depth of 125-500 meters and is observed from the Velistsikhe station to the Gumbati village over 140 km. This horizon submerges to the same direction as the Telavi one.
Gurdjaani horizon is formed by porous gravely sediments with sandy fillers. Its capacity reaches 80 meters, gradually turning smaller towards the south –east direction. In its section about nine water-bearing layers are distinguished capacity of which fluctuates from 1 to 60 meters. The maximum number of these layers is observed in Gurdjaani-Kardanakhi region. Almost the whole horizon is covered by the above described Telavi water-bearing horizon.
Water conductivity coefficient of the Gurdjaani horizon amounts to 150-300 m2/24 h. Debits of boreholes at the well-spring predominantly equals 1-5 l/sec, specific debits range from 0, 13 to 2, 15 l/sec.
According to the chemical content, the pressure waters of the Gurjaani horizon are represented mainly by the waters of moderate mineralization (0,6-1,32 g/l), belonging to the hydrocarbonate calcium-natrium, hydrocarbonate-chloride natrium-calcium or the hydrocarbonate-sulphate natrium-calcium types. Total hardness is 1-6, 5 mg/equiv. In the lower water-bearing layers of Kardanakhi-Tsnori mineralization of the waters reaches 18 g/l with hydrocarbonate-chloride natrium chemical content which may be explained by the spilling over of underground highly mineralised chloride-natrium waters from infra-lying mezo-cainozoic sediments. Gurdjaani and Telavi water-bearing horizons are fed at high mountaneous part of Kakheti range north-eastern part, which is the south side of the Alazani artesian basin.
Common decline of piezometric surface (that is unloading of water-bearing layers) occurs in the north-eastern direction towards the central strip of the artesian basin. Therefore (Consequently), it should be supposed that eastwards of Lagodekhi meridian the ground-waters from this water-bearing horizon spill over to the Agrichai part of the Alazani-Agrichai artesian basin across the area bordering with Azerbaijan.
For the purpose of assessment the amount of spilling over ground-water the special thematic hydro-geological work should be carried out.
In contrast to the rest of artesian basins, features of Iori-Shiraki artesian basin lies that within this basin water-bearing horizon of Akchagil-Apsheron sediments, not widely spread, is developed locally within the boundaries of monoclinal and synclinal structures to which are attributed the following, even lesser in size, artesian basins of the third order: Sartichala, Sagaredjo, Mtsvanemindori, Shairaki, Olei and Djeiran-Choli. Hydro-geological characteristics, as well as quantitative and qualitative assessment of ground-waters of the water-bearing horizon under consideration are given separately in Table 1.

As it is obvious, the water-bearing horizon concerned is the most rich in water and perspective promising both with regard to the amount of natural resources and qualitative indices of ground waters within Sagaredjo and Mtsvanemindori artesian basins. Filtrating features of the whole water-bearing horizon as well as its separate water-bearing layers, two-three times exceed these features within other artesian basins of the same order (that is of the third order) of the Iori-Shiraki artesian basin.


Sagaredjo and Mtsvanemindori basins are also distinguished by rather favourable conditions of feeding areas which are mainly situated high, in the mountainous part of the axled zone of Kakheti range, while the areas of pressure and unloading are situated much more lower – in the valley area which conditions significant superfluous pressures of artesian waters, intensive flushing of water-bearing layers and low mineralization of ground waters.
1.5. Sporadically water-bearing lagoon-continental sediments myopliocene are widely spread within the Kartli Tiriphono-Nukhrani, and Marneuli-Gardabani artesian basins. They are represented by the conglomerates on clay-lime cement, more rarely – sandstones and clay. Sometimes porous conglomerates with arenaceous fillers occur. The latter, as well as cracked sandstones are water-bearing. Total capacity of this complex increases eastwards and reaches 3000 meters.
In Kartli artesian basin at the depth of 500 meters with the help of boreholes three water-bearing layers have been revealed with the total capacity from 3 to 70 meters. Water-bearing layers do not differ from others by their areal spread and capacity. Debits of boreholes (wells) fluctuate within 0, 1-5, 7 l/sec at the well-spring. Most of the wells are sub-artesian with piezometrical levels up to 42 meters lower the soil surface. Excess pressure in the wells reaches 10 meters.
Within Tiriphon plain the area of water-bearing horizons feeding is situated on the eastern spurs of the Surami range and southern foothills of the Greater Caucasus range. In Mukhrani valley and to the east the feeding is occurring both from the north and south.
Ground waters are unloaded in the southern and central parts of the depression of the Kura, Liakhvi, Ksani, Medjuda, Aragvi rivers valleys, etc.
Mineralisation of downstream waters is from 0, 3 to 1 g/l. Main chemical composition of the given horizon is hydrocarbon calcium-magnesium, hydrocarbon-sulphate-natrium-calcium. Common hardness is within 2-3 mg-equiv.
In Marneuli-Gardabani artesian basin in the southern-east part of Gardabani plain with the boreholes to the depth of 200-450 meters in porous sandstones four artesian horizons have been revealed with the total capacity from 9 to 20 meters. Their piezometric level fluctuates within plus 10-12 meters, water conductivity coefficient equals 6,5-135 m2/24 h. Specific debits (discharge) of the wells reach 0,5 l/sec, in the lowest horizons there are mineralized chloride sodium waters.
1.6 Water-bearing complex lower-pliocene-miocene volcanic-continental sediments is spread within Akhalkalaki and Erusheti lava plateaus and is represented by andesite, andesite-dacides, liparites lavas and their pyroclastic deposits.

Most abundant in water are the andesite and andesite-dacides lavas. The depth of deposition of interstitial waters fluctuates from 20 to 150 meters. The highest discharging sources (up to 100 l/sec) situated in the upper cource of the rivers Kvabliani, Uraveli, Indji-Su and others, belong to the lava streams of andesites.


Sediments of the horizon contain exceptionally gravity (free-flow) waters, only on the territory of the Tabatskuri lake in the andesites blocked by the sandy-clay lake sediments, fresh drinking waters are revealed with the help of boreholes (wells).
ground waters of the complex are distinguished for their low mineralization mainly up to 0,3 g/l and hydro carbonate-calcium or calcium-sodium composition.
The water-bearing complex is fed predominantly at the expense of atmospheric precipitation and some places at the expense of ground waters of upper-nepliocene-middle-quaternary lava coverings. The areas of feeding and unloading often coincide with each other. The regime of the sources situated in deep canyons is rather steady.
Ground waters of the given horizon are widely used for water-supplying purposes of big settled areas (Akhaltsikhe, villages Adigeni, Uraveli and others).
1.7. Water-bearing complex of middle-eocene marine volcanogenic deposit sediments is particularly widely spread within the Lesser Caucasus in Adjaro-Trialeti folded system and is represented by the coverings of lava andesites, tuff-sandstones, terrigenous sandstones. Capacity of the complex constitutes 3 km on average. Paleocene-lower-eocene flysch sediments serve as its waterproof bed, while waterproof powerful clay-marly formations of upper Eocene serve as its roofing.

II. fractured ground, zone


In the zone of weathering, in particular in the pivotal parts of anticlines, volcanogenic layers are characterized by intensive fracture, due to which this zone is rich in ground waters, formation and unloading of which is taking place upstream the local base of erosion.
Deeply penetrating fracture is observed in the zones of tectonic break-ups, due to which in this complex is formed rather big quantity of fracture-vein and fracture-bedded waters, circulating, mainly, below (lower) the zone of erosion shear mainly forming thermal waters, the most significant of which are high-debit Tbilisi, Asureti, Akhaldaba, Tashiskari, Aspindza, Abastumani, Zekari and other sources of thermal waters (Table 2).
In these deposits boreholes have been laid on different structures causing the well-spring of thermal waters, very frequently with significant debits – up to 25 l/sec (Table 3).
Ground waters under consideration are mainly characterized by low mineralization (0,2-1,0 g/l), which is caused by the wide opening of hydro-geological structures of Ajara-Trialeti folded system. Chemical composition of water is distinguished by diversity; however prevailing type here is hydrocarbon-sulphate calcium-natrium. At the deeply submerged areas of hydro-geological structures (eastern part of Tbilisi source and others) chloride-sodium waters with relatively increased mineralization (up to 5 g/l) have been revealed (bored) (Table 3).
Out of gas composition of low-mineralized waters dominant role plays nitrogen of atmospheric origin with low composition of hydrogen sulphide, while in the mineralized waters of closed structure – methane.
The water-bearing complex contains significant resources of ground-waters, which are fed by atmospheric precipitation and surface waters at elevations and open strips of permeable layers.
1.8. Water-bearing horizon of paleogenetic and upper-Cretaceous carbonate deposits is formed by thin-layer (coating) limestone and marl, seldom - by clay marls with the capacity up to 1600 meters. The layers of this horizon are becoming uncovered at a lot of strips of the Trialeti range, particularly – in the districts where the sources of Borjomi mineral waters are fed, Tbilisi artesian basin, along Surami-Gokishuri deep-laid break-up, canyon type ravine of the Khrami river and crest part of the Kakheti range.
To the upper zone of exogenous fissuring belong multiple interstitial and interstitial-karst sources of ground waters with significant debits (30 and more l/sec).
Ground waters of this zone are characterized by low mineralization from 0, 15 to 0, 5 g/l, predominantly hydro-carbon-calcium-magnesium composition.
Water-bearing horizon in the central part of Trialeti range is highly elevated, though submerging to the eastern direction along several kilometers in troughs, is elevating at the same time, and sometimes becomes uncovered in anticline (arches). Thanks to this, favorable conditions are created for the formation of deeply circulating, diverse according to mineralization, chemical and gas composition of ground mineral waters, rather valuable from the point of view treatment and drinking purposes (usage). Particularly should be distinguished the fields of soda mineral water “Borjomi”, “Ude”, “Zanavi” and saline-alkaline waters like “Esentuki-Vardzia” (Table 4).

Table 3



Name of


Water-development


Interval of

water-development



Geological

index


Water

temper. 0С



Debit

l/sec


Water

miner


ali

zation, g/l


Dominant


content of

solute


gases

1

2

3

4

5

6

7

Akhaltsikhe ad-artesian basin




Tskhaltbila, well (borehole) 4

34-380

Pg22

23

6

0,2

Nitrogen

Tsinubani source (Atskuri)




Pg22

26

1

0,16

Nitrogen

Tsinubani (Atskuri)

25-477

Pg22

38

16

0,2

Nitrogen

Akhaltsikhe, well (borehole) 1

935-1006

Pg22

37

10

10,3

Carbonic acid

Tskhaltbila, source (Rustavi)




Pg22

22

0,5

0,6

Nitrogen

Abastumani, “Hercules” source




Pg22

48

12,5

0,5

Nitrogen

“Aspindza” source




Pg22

38

3

0,9

Nitrogen

Aspindza, well (borehole) 8

361-365

Pg22

42

10

1,5

Nitrogen

In total over the region












59







Trialeti pressure-water system




Tsikhisdjvari, well (borehole) 19

55-300

Pg22

32

12,1

0,1

Nitrogen

Dviri, well (borehole) 14

720

Pg22

29

2,7

0,3

Nitrogen

Likani, well (borehole) 26

487-800

Pg22

33

4,2

0,1

Nitrogen

Likani, well (borehole) 2

800-850

Pg1-Pg12

40

2

5,4

Carbonic acid

Sadgeri, well (borehole) 10

51-653

Pg22

33

2,4

0,5

Nitrogen

Akhaldaba, well (borehole) 16

354-385

Pg22

32

6

0,2

Nitrogen

Tashiskari, well (borehole) 7

800

Pg22

34

2

0,2

Nitrogen

Baniskhevi, well (borehole) 27

500

Cr2

27

5

0,7

Carbonic acid

Borjomi, well (borehole) 35

400-500

Pg1-Pg12

28

1

0,34

Nitrogen

Kvishkheti, well (borehole) 28

900-1044

Pg1-Pg12

28

2,5

0,37

Methane

Rveli, well (borehole) 39

1200

Cr2

26

12

0,9

Methane

Kvibisi, well (borehole) 38

1200

Cr2

39

22

6,4

Carbonic acid

Zanavi, well (borehole) 40

1000

Pg22

30

0,5

1,2

Methane

Vashlovani, well (borehole) 25

850-1050

Cr2

41

12,5

7,2

Carbonic acid

Kvibisi, well (borehole) 47

1200

Cr2

38

25

4,8

Carbonic acid

Kvibisi, well (borehole) 37

1200

Cr2

36

7

7,0

Carbonic acid

Borjomi, well (borehole) 4а

400-960

Cr2

32

0,5

6,9

Carbonic acid

Borjomi, well (borehole) 1

194

Cr2

35

6

5,9

Carbonic acid

Borjomi, well (borehole) 41а

130

Cr2

32

1,5

6,3

Carbonic acid

Borjomi, well (borehole) 5

915-1200

Cr2

37

1

6,6

Carbonic acid

Papa, well (borehole) 1

500

Pg1-Pg12

28

1

3,5

Carbonic acid

Mitarba, well (borehole) 18

60-540

Pg22

26

0,5

2,8

Carbonic acid

Nunisi, group of sources




Pg22

28

2,3

0,2

Nitrogen

Nikabeti source




Pg22

24

2,6

2,5




In total over the region














134,3










1

2

3

4

5

6

7

Tbilisi ad-artesian basin




Tbilisi, well (borehole) 1

24-43

Pg22

34

10,2

0,39

Nitrogen

Tbilisi, well (borehole) 2

35-75

Pg22

42,5

1,5

0,42

Nitrogen

Tbilisi, well (borehole) 4

39-55

Pg22

44

0,7

0,33

Nitrogen

Tbilisi, well (borehole) 6

40-140

Pg22

29

1,2

0,93

Nitrogen

Tbilisi, well (borehole) 7

58-76

Pg22

38

1,9

0,7

Nitrogen

Tbilisi, well (borehole) 8

40-80

Pg22

46

5,4

0,3

Nitrogen

Tbilisi, well (borehole) 1 гл.

350-1245

Pg22

48

4,0

0,3

Nitrogen

Tbilisi, well (borehole) 5 гл.

23-1300

Pg22

44

7,0

4,7

Methane

Tbilisi, well (borehole) 7 гл.

1485

Pg1-Pg12

27-52

8,1

3,0

Methane

Tbilisi, well (borehole) 3 гл.

500-1300

Pg22

38

0,9

0,8

Methane

Tbilisi, well (borehole) 8 гл.

250-968

Pg22

50

5,8

0,39

Methane

In total over the region














46,7






As the depth of disclosure of the water-bearing horizon increases, total mineralization of water grows up to 10-15 g/l and its type comes close to chloride-natrium (sodium). However, in some zones, particularly in the zone of Borjomi mineral water deposit in the deep parts of the horizon in the Banis-khevi river canyon in the borehole (well) N27 at the depth of 1200 meters, laid at the roof part by Lomismtis anticline, hydro-carbon-sodium waters with the mineralization up to 0, 3 g/l and debit 5 l/sec. have been revealed. On the same structure 5 km eastwards from the above-mentioned place with the borehole of 1 400 meters depth between the depth of 950-1200 meters have been revealed chloride hydro-carbon sodium-calcium water with the mineralization up to 0, 8 g/l.


All said witnesses the fact that Borjomi mineral water field is typical example of hydroinerttia-impulsive fields the resources of which are formed through the mixing of infiltrogenic fresh ground waters of paleogen- upper-cretaceous carbonate deposits with the incoming through the tectonic breaks from depth of carbonic, mineralized (15-25 g/l) chloride-hydrocarbon-sodium waters.
1.9. Water-bearing horizon upper-cretaceous carbonate flysch of the Southern slope of the Greater Caucasus is stretched at a great distance along the border of Georgian lump, between two rivers Ksani-Alazani, becoming uncovered in the form of narrow strips elongated at the troughs of synclinal folds. Lithologically the horizon consists of limestone, marl and sandstones. Deposits of the horizon are intensely folded, as a result of which the layers are represented in the form of compressed isoclinal and inverted to the south and thrust torn folds. The strata, because of intensive fissuring and karst, are characterized by high water permeability and water abundance.
Because of the absence of boreholes it is possible to characterize the water content only of the zone of active circulation. The most significant water-development is observed between Ksani and Aragvi ( Pshavi and Mtiuleti). Here to the limestones of upper-cretaceous are related outlets of high-flow-rate springs near the villages Bibiloiani, Tsinamkhari and others. The most powerful are karst sources of Saboloki, Sodeva and Meniso villages (Table 5), feeding, basically, side inflows of the main water-ways.
Ground waters of the horizon, are mainly characterized by low mineralization (0,2-0,6 g/l), hydrocarbon sodium-magnesium or calcium-sodium. They are widely used for industrial and drinking purposes of settled areas, cattle breeding farms and summer distant-pasturing cattle-breeding.

Table 5

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