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` The Dâmbovicioara Passage consists of awide syncline structure that extends between themountains Leaota and Bucegi to the east, and thecrystalline body of the Southern Carpathians tothe west. Within its fan-shaped domain, widelyopened toward Braºov Depression (to the north),and closed (to the south) by the crystalline base-ment uplift of Dragoslavele area, two distinctgeomorphologic units occur: Piatra Craiuluimountains body and Rucãr-Bran trench.

1. PhysiographyThe rough topography of the passage, with its

western limb uplifted in Piatra Craiului mountainsbody, includes a folded structure that consists of asuccession of synclines and anticlines, highly dis-sected by transverse and longitudinal faults whichdelineate three large tectonic depressions: Bran,Podul Damboviþei and Rucãr.

Piatra Craiului mountains body, shaped en-tirely in a Tithonic limestone substratum, is strik-ing mainly north-south and reaches its maximumelevation (2238.7 m) in the peak �La Om�. Thenorthern section of the mountain-ridge exhibits agradual clockwise bending, so that eventually, start-ing from Turcului peak (1923 m), the ridge assumesan overall southeastward-directed strike, in a regionthat is designated as Piatra Craiului Micã.

The mountains body topography is domi-nated by the main ridge, which extends betweenthe settlements Zãrneºti and Podu Dâmboviþei(Fig. 1). With its jagged appearance and a widththat occasionally does not exceed 1 m, the ridgedominates the region where the junction betweenthe Eastern and the Southern Carpathians occurs.The total length of the ridge amounts to 23 km,while the width of the carbonate deposits whichbuild it up ranges between 0.4 and 2 km. The con-sidered limestone outcrops occupy an area extend-ing over 25 km2.

Rucãr-Bran trench lies sunken about 1000 mbelow the stone cliffs which border it to the east

3.5. DÂMBOVICIOARA PASSAGEby Iancu ORêEANUIancu ORêEANUIancu ORêEANUIancu ORêEANUIancu ORêEANU

Romanian Association of Hydrogeologists, ianora@hotmail.com

and to the west, its elevation being symmetricallydistributed with respect to a maximum altitudecentral axis that strikes NW-SE, along the linea-ment Fundata-La Table-La Om peak. Divergentlyfrom that lineament, the ground elevation gradu-ally falls by roughly 600 m to the NE, down toZãrneºti embayment � a distinct section of Braºovinter-mountain depression - and to the SE, downto the sub-Carpathian depression of Câmpulung.Considered as a whole, that region breaks the geo-graphical continuity of the Southern Carpathians,being recognized and intensely used as a travelingpass since ancient times.

The limestone ridge Gâlma Pleºii, which ex-tends between Vlãduºca valley and the settlementCiocanu, is the central topographic feature of thepassage area. Between that ridge and the mainridge of Piatra Craiului there occur the upperreaches of the Dâmbovicioara stream catchmentarea.

Streamflows located in the northern sectionof the passage - Prãpastiei, Turcului (Sbârcioarei),Moeciu and Simion - are tributaries of Bârsa river,while those occurring further to the south aretributaries of Dâmboviþa. That latter river has en-trenched in the Late Jurassic limestone depositsbelonging to the Piatra Craiului syncline southernsector a couple of spectacular gorge sections, whichare separated from one another by the tectonicdepression of Podu Dâmboviþei, where the junc-tion with Dâmbovicioara stream occurs. Tributar-ies are absent along the gorge section designated as�Cheile de Sus�, which precedes the above-indi-cated depression; conversely, two significant tribu-taries, Cheia and Ghimbavu, join the main river inthe gorge section located further downstream(�Cheile de Jos�).

The commissioning of Clãbucet hydropowerstation and of the associated reservoir-lake atPecineagu (1983) has induced in the Dâmboviþastream discharge a pulsatory regime. In terms ofkarst-related processes, the latter circumstance re-sulted in enhanced seepage through the streambed

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- a consequence of alluvial deposits being washedout and of cracks becoming un-clogged. Conse-quently, nowadays, during the low water season,about 200 l/s of the total discharge of the riverDâmboviþa is sinking in the underground in thegorge section �Cheile de Sus�.

The upper reaches of Dâmbovicioara streamoccur south of the La Table area (1376 m eleva-tion), with the corresponding various stream sec-tions being designated as Valea Lupului (down tothe junction with Grind brook), Seaca Pietrelorvalley (down to the junction with Valea cu Apã),Brusturet valley (down to Gâlgoaie). In that latterspot, the Gâlgoaie - La Bile group of springs con-tribute with substantial amounts of water-inflows,while further downstream the watercourse bearsthe name Dâmbovicioara. During most part of theyear, Valea Lupului and Seaca Pietrelor valley sec-tions are devoid of water, which is sinking throughthe streambed alluvia into the conglomerate orlimestone substratum. Actually, every right-sidetributary coming from Piatra Craiului mountainsbody (namely Valea cu Apã, Valea Muierii, ValeaPeºterii, Valea Popii) is subject to a hydrologicalregime analogous to that of the above mentionedvalley sections. There occur no landforms whichcould be ascribed to the classical �swallet� or �blindvalley� types.

At the junction with Valea Peºterii, inflowsprovided by the springs �din Plai� result in a sig-nificant increase of the flow-rate of Dâmbovicioarastream. Still further downstream, there occur onlytemporary and low discharge tributaries, both onthe main stream left side (Valea Izvoarelor) andright side (Valea Popii, Brãtoaia valley).

Dâmbovicioara stream catchment area ex-tends over 49.1 km2, at an average altitude of 1195m, with the elevation drop between the head wa-ter area (La Table, 1376 m) and the junction withDâmboviþa river (737 m), amounting to 639 m.When considered only down to Gâlgoaie region,the catchment area of Dâmbovicioara streamamounts to 24.4 km2, extending at an average al-titude of 1450 m.

1.1. Climate dataA significant number of meteorological sta-

tions (6) and rainfall gauging stations (14) occurwithin the Rucãr-Bran trench realm, a circum-

Figure 1. Hydrogeological map of DâmbovicioaraPassage. (Geological data after R. Dumitrescu et al.,1971, 1974, D. Patrulius et al., 1971, M. Sãndulescuet al., 1972).

Legend:1 Thick series of Mesozoic carbonate deposits,

highly fractured and moderately karstified, dis-playing very high effective infiltration values andbeing subject to intensive groundwater flows. Im-portant water resources in large karst systems;

2 Coarse, prevalently carbonate molasse depositsof Late Aptian age (carbonate conglomerates andbreccia), subject to groundwater flows throughfissured, porous and karst media. High effectiveinfiltration values are suggested by the temporarycharacter of the surface flows. Important re-sources supplying the underlying karst aquifer;

3 Vraconian-Cenomanian molasse deposits(sandstones, conglomerates, shales) subject togroundwater flows through porous-fissured me-dia. Aquifer accumulations supplying the underly-ing karst aquifer and permanent surface flows;

4 Quaternary unconsolidated detritic deposits(sands, gravels, occasionally clays) of reducedthickness and extent, subject to intensivegroundwater flows and hosting reducedgroundwater resources of local importance (1-Holocene; 2a-Pleistocene; 2b-slope debris);

5 Metamorphites with extensive fracture networksand a well-developed weathering zone, whichprovide a continuous and important supply towardriver flows and binary karst systems;

6 Marly and argillaceous deposits, devoid ofgroundwater flows;

7 Perennial stream course;8 Temporary stream course;9 Fault;

10 Abrupt;11 Watershed;12 Underground flow connection proven by tracer

tests;13 Road;14 Direction of hydrogeological cross section;15 Swallow hole, swallet;16 Site of tracer injection into flow sinking diffusely

through the streambed;17 Group of springs of 20 l/s cumulated discharge;18 Karst depression;19 Saddle;20 Tourist and forestry chalet;21 Shelter;22 Shephards� hut.

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stance which contributed to a proper knowledge ofthe topoclimate (local climate) of that area. Thattopic has been addressed in detail in the work ofELENA TEODOREANU: �Rucãr-Bran trench.A study of its climate and topoclimate�, publishedby the RSR Academy publishing house in 1980,and having served as a basis for the presentation ofthe data below.

The prevalent atmospheric circulation occursfrom the west, and together with its associatedcomponents, from the northwest and from thesouthwest, it contributes to a total of 56% of theoverall frequency of atmospheric circulation direc-tions. The western air-circulation is chiefly associ-ated to mild winters and to frequent precipitationsthat occur mainly as rainfall, while turning, athigher altitudes, into sleet and snow. There is aremarkable degree of thermal instability during thewarm season, when rainfall is also accompanied bythunderstorms.

The areal distributions of the average annualair temperature and of the average amount ofprecipitations are a function of the variations in thetopography elevation (Fig.2). The average annualtemperature is 7.2°C at Rucãr and 4.4°C at

Figure 2. Distribution of the average air temperature (left) and of the average amount of precipitations(right) across Dâmbovicioara Passage (after Elena TEODOREANU, 1980).

Fundata, being estimated to reach about 0-2°C onthe Piatra Craiului ridge, with thermal gradientsvarying from 0.49°C/100m in the lower section ofthe passage, to 0.60°C/100m on the borderingmountain slopes.

Up to 1700-2000 m elevation, the atmos-pheric precipitations amount increases along withthe altitude, while further up it starts to decrease.By considering the passage as a whole, there hasbeen estimated that the precipitations amountincreased from south to the north, and from est tothe weast. Precipitations reach their maximumamount in June, the lowest monthly amount beingrecorded in February-May. At Podu Dâmboviþei,the largest number of rainfall days is recorded inthe month of May, while March and Septemberare the months when the smallest number ofrainfall days occurs.

During the X.1979-IX.1980 time-interval,when a temporary meteorological station had beeninstalled at Dâmbovicioara settlement, the poten-tial evapotranspiration (PET) was estimated toreach 42% of the total rainfall amount, while thereal evapotranspiration (RET) amounted to only22.4% of the same reference quantity.

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2. A brief history of geographical andgeological research

The distribution and the evolution of thelandforms of Piatra Craiului mountains body havebeen addressed by detailed investigations conductedby A. BÂRSAN (1969), M. CONSTANTINESCU(1941), E. NEDELCU and ª. DRAGOMIRESCU(1963). Several papers concerning the landforms, theflow network, and the overall evolution of thatmountains body have been published by T.CONSTANTINESCU, the derived results beingconcentrated in that author�s PhD thesis, the pres-entation of which was delivered at the University ofBucharest in 1994.

A study of Rucãr-Bran trench in terms of cli-mate and topoclimate has been conducted byELENA TEODOREANU (1980), who consideredclimate data series extending as recently as 1970.

The present-day knowledge concerningDâmbovicioara Passage in terms of geology is theresult of a multitude of studies and investigations.An early stage of research has been carried out be-tween 1888 and 1940, including paleontologydata inventories and monographic works devisedby HERBICH (1888), Gr. COBÃLCESCU(1890), I. SIMIONESCU (1897-1899), and E.JEKELIUS (1926).

A new stage in the geological research of thatarea has been initiated by the publication of thedetailed geological maps devised by N. ONCESCU(1943) and by D. PATRULIUS (1955, 1960,1963, 1969); it has been later continued by inves-tigations conducted by GR. POPESCU (1952), FL.MARINESCU (1955), I. NEDELCU (1957) ad-dressing limestone and dolomite deposits, by inves-tigations focused on stratigraphy and on paleon-tology, undertaken by ILEANA POPESCU (1966,1969), and by geological prospecting for phosphatesaccumulations, performed by MAGDALENARADU and ALEXANDRINA ANTONESCU(1977).

The sheets Bârsa Fierului, Zãrneºti, Moeciuand Rucãr, of the geological map of Romania atthe 1:50,000 scale, illustrate the current geologi-cal and structural concepts regarding that area.

Over the time-interval 1979-1980, the Geo-logical Company for Solid Mineral SubstancesProspecting (presently S.C. Prospecþiuni S.A.) has

conducted a detailed hydrogeological survey ofDîmbovicioara Passage (IANCU ORêEANU,NICOLLE ORêEANU, N. TERTELEAC), ad-ditional contributions in terms of hydrologicaldata collection and processing having been provid-ed by the Institute of Meteorology and Hydrolo-gy (AL. BULGÃR, ª. DÃSCÃLESCU, S.CRÂNGAªU, V. BÃDESCU, I. MUNTEANU,GH. HOÞOLEANU, P. HOÞOLEANU and D.DEMETRIAN). Besides, T. CONSTANTINES-CU from the Institute of Speleology �EmilRacoviþã� in Bucharest, has contributed to the as-sessment of the soil groundwater reserve, while E.GAªPAR and T. TÃNASE, from the Institute ofNuclear Physics, have contributed to conductingtracer tests by means of radioactive and activabletracers. A series of limited results derived from theabove-mentioned broad-scale hydrogeologicalstudies have been published by I. ORêEANU,AL. BULGÃR, E. GAªPAR, N. TERTELEAC(1984). Over the time interval 1989-1990, S.C.Prospecþiuni S. A. resumed hydrogeological inves-tigations addressing Dâmbovicioara Passage (IAN-CU ORêEANU, NICOLLE ORêEANU),then, between 2003-2005, S.C. Cheresta SRLDâmbovicioara has funded additional hydrogeo-logical studies aimed at the certification of Gâlgo-aie spring as a still water source (I. ORêEANU,S.C. Cheresta SRL Dâmbovicioara archives.).

3. Geological frameworkThe crystalline basement of the passage has a

continuous dip to the north, interrupted by atransverse uplift extending between Coacazeibrook and La Om peak. It underlies a thick se-quence of Jurassic and Cretaceous deposits, includ-ing in their lower half highly fractured, 700-1200m thick Kimmeridgian-Tithonic limestones, mostof it compact and layered.

In the western part of the passage, limestonesbuilds up a north-south striking structure, desig-nated as Piatra Craiului syncline: its western limbis dramatically turned up, to build up PiatraCraiului ridge, the eastern limb is outcropping inGâlma Pleºii ridge, while within the syncline axisthere occurs a filling of Late Aptian carbonate con-glomerates.

The Late Jurassic limestones is underlain bydeposits which disconformably overlie the crystal-

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line schists, and which consist of Bajocian-Callovian deposits (marly limestones, carbonatesandstones, carbonate marls, of 60 m cumulatedthickness) and of Medium Oxfordian-Calloviandeposits (limestones with cherts, arenitic lime-stones, of 40 m cumulated thickness), occurring astwo parallel stripes on the western slopes of PiatraCraiului. Within the passage, they occur aroundthe crystalline schists outcrops and their overallhydrogeological behavior is similar to that of thelimestone.

The Late Jurassic limestones is overlain bylimestone, marls and marly limestones of Hauteriv-ian age, which underlie a thick stack that includesimpervious Barremian marls and marly limestones,as well as Bedoulian marls and reef limestones.

Late Aptian deposits include carbonate andpolymictic conglomerates, and carbonate breccias(designated by ILEANA POPESCU, 1961, as�Gura Râului conglomerates�), which outcropover large areas in the Dâmbovicioara syncline axis.They are crossed by dense networks of cracks, theirpermeability is high, and valleys for which theyprovide the substratum are commonly dry, becauseof the fast infiltration rates favored by those rocks.They exhibit a mixed hydrogeological behavior,the high porosity induced by cracks and inter-granular spaces being additionally associated witha karst component, induced as a result of the dis-solution of the limestone pebbles and of the car-bonate cement they are made of.

Vraconian-Cenomanian deposits includemassive sandstones and polymictic conglomerates,micaferous sandstones and carbonate breccia, alter-

nating with marly shales. They disconformablyoverlie older formations and extend over large ar-eas, bordered by fractures, in the western and thesouthern regions of the passage. The aquifer accu-mulations they host are discharging through amultitude of low flow-rate springs.

4. Water budgetEnsuing to activities carried out in cooperation

by S.C. Prospecþiuni S.A., INMH and ISER, therehave been collected data concerning precipitations,surface runoff, and variations in the soil groundwa-ter reserve which had occurred within Dâmbovicio-ara Passage during the time-period 1979-1980, thecollected data being further used in devising thewater budget of both surface and undergroundflows, over the water-year XI.1979-X.1980. A lim-ited amount of the corresponding results has beenpublished by ORêEANU I., AL. BULGÃR, E.GAªPAR and N. TERTELEAC (1984).

The devised water budget has once againproven that in terms of specific discharges, karstprocesses result in major alterations, which mirrorthe absence of correlation between the extensionof the topographic watersheds, and the actual ex-tension of the karst systems. Specifically, by takingas a reference the specific discharge recordedwithin the catchment area of Râuºor steam, a wit-ness catchment area that extends over imperviousrocks, there can be noticed that in terms specificdischarges, major deviations occur in the case ofcatchment areas extending prevalently over a lime-stone substratum (Table 1 and Fig. 3).

F - surface of the catchment area; H - mean altitude of the catchment area; Qmean - mean annual discharge;q - mean annual specific discharge. (No. 1, 2 and 3 after AL. V. STÃNESCU, 1966.)Table 1. Morphometric and hydrometric data.

No. River Flow rategauging station

Period Fkm²

Hm

Q meanm³/s

ql/s/km²

1 Dâmboviþa Valea lui Ivan 1954-1964 165.4 1530 3.82 23.1

2 Dâmboviþa Podu Dâmboviþei 1949-1964 251 1375 4.73 16.8

3 Dâmboviþa Malu cu Flori 1931-1949 679.7 1131 9.22 13.5

4 Râuºor Rucãr X.1979-IX.1980 52 1201 0.91 17.5

5 Dâmbovicioara Podu Dâmboviþei X.1979-IX.1980 49.1 1195 0.615 12.6

6 Prãpastiei Zãrneºti X.1979-IX.1980 22.6 1390 0.857 37.9

7 Turcu Moeciu X.1979-IX.1980 45.5 1250 0.328 7.2

8 Dâmboviþa Dragoslavele X.1979-IX.1980 450 1310 8.39 18.6

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Rainfall occurring on the surface occupied bythe sedimentary deposits of Dâmbovicioara Pas-sage (approximately 230 km2) has generated dur-ing the time-interval XI.1979-X.1980 a wateramount of 570.3 mm (4.1 m3/s) available for run-off and infiltration. Out of it, 75% (3.1 m3/s) in-filtrated in the underground, while 25% wasevacuated outside the surveyed area by surfaceflows. The infiltrated water amount has contrib-uted to restoring the groundwater reserves, con-stantly drained by the springs which discharged atthe passage-region boundaries. Out of the infil-trated water amount, almost half is dischargedthrough three main groups of springs, those inPrãpãstiile Zãrneºtilor (790 l/s), those in �Cheilede Jos�, along the streamcourse of Dâmboviþa (800l/s), and those of Gâlgoaie, in the catchment areaof Dâmbovicioara (320 l/s).

For the catchment area of Prãpastia stream, theannual water budget of the surface and undergroundflows outlines additional inflows exceeding by 3 mil.m3 the water amount which would be available ifsolely the area bounded by the surface watershed(22.6 km2) was taken into account. In fact, the flowdischarged by this specific catchment area corre-sponds to a surface of 52 km2. If there is in additiontaken into account also the surface of about 5km2corresponding to the recharge area of Topliþaspring (which discharges about 100 l/s of water fromthe same structure, along a transverse fault) the actualrecharge area amounts to a total of about 57 km2.

The additional recharge of those groundwateroutlets derives from a region extending over a sur-face of about 34 km2, which includes the limestonesoutcrops on the northwestern slopes of PiatraCraiului (about 9 km2) and a large part of the catch-ment area of Turcului (Sbârcioarei) stream.

Figure 3. The relationshipbetween the mean annualspecific discharge (q) andthe mean altitude ofcatchment area. Signifi-cance of numbers as intabel 1.

The catchment area of Turcului stream ex-tends over 45.5 km2 and its annual discharge, asrecorded by Moeciu flow gauging station, amountsto 10.35 mil. m3. That catchment area is subjectto a flow deficit of about 12 mil. m3, the corre-sponding water volume being diverted towardPrãpastia valley. The underground water dividebetween the groundwater flow systems associatedto Prãpastia and Turcului streams cannot be tracedaccurately, except for the western segment, whereit follows the crystalline schists outcrop boundary.

Over the time-interval XI.1979-X.1980, rain-fall occurring in the Dâmbovicioara catchmentarea (that extended over 49.1 km2) amounted toan average value of 849.2 mm (41.7 mil. m3/year),out of which real evapotranspiration eliminated277.6 mm (13.6 mil m3/year; 32.7 % of the rain-fall amount), while 19.55 mil m3/year (620 l/s;46.9 % of the rainfall amount) discharged as sur-face flow.

The water budget of the surface and under-ground flows of the Dâmbovicioara stream catch-ment area indicated a deficit of 8.6 mil.m3

(272.7 l/s = 5.55 l/s/km2; 17.4 % of the rainfallamount), that groundwater amount being divert-ed out of the Dâmbovicioara stream catchmentarea, to finally emerge as part of the discharge(800 l/s) of the outlets in �Cheile de Jos�, along thestreamcourse of Dâmboviþa.

Out of the total surface flow discharged byDâmbovicioara catchment area (620 l/s), the320 l/s contribution of Gâlgoaie springs represents51.6 %, which amounts to 24.2 % of the rainfalloccurring in that catchment area.

There is estimated that within the catchmentarea of the Dâmbovicioara stream segment whichextends upstream the springs-group Gâlgoaie

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(F=24.4 km2, H med=1450 m), there is availablefor runoff and infiltration a water amount of 440l/s, out of which 40 l/s flow down the streamBrusturet, 320 l/s are discharged by the springsGâlgoaie, while the remaining 80 l/s assumedlyflow underground, underneath Gâlgoaie springs,further downstream.

There are 24.7 km2 of additional catchmentarea which belong to the segment of Dâmbovicioarastream that extends 7 km downstream the springs-group Gâlgoaie, down to the junction with the riverDâmboviþa. That stream section is subject to oppos-ing actions, induced by two distinct factors: (a)water inflows provided by spring discharges (e.g.Izvoarele din Plai) and by precipitations falling onthe catchment area, the overall result being an in-crease in the flow-rate of the surface stream, and (b)diffuse infiltrations of surface waters into the car-bonate deposits and/or the conglomerates, occur-ring both through the streambeds of the maincourse and of its tributaries, as well as through theentire surface of the catchment area, the overall re-sult being a reduction of the flow-rate of the surfacestream. The rainfall regime controls the positive ornegative balance between those two factors.

During the years 1979 and 1980, along theriver Dâmboviþa and along its main tributaries,flow gauging has been conducted both perma-nently and occasionally (during field trips), thatundertaking resulting in a large amount of signifi-cant information concerning the karst flow regime.Specifically, along the �Cheile de Sus� gorge sec-tion, streambed seepage results in a reduction ofthe Dâmboviþa river flow-rate. Apart from contri-butions provided by the Dâmbovicioara and Cheitributaries, the same flow-rate reduction regime isnoticeable also along the �Cheile de Jos� gorgesection; it is only about 300 downstream the junc-tion with Cheia stream that the river flow startsincreasing, due to inflows which extend down tothe gorge termination and which provide a total of800 l/s (supplied by a springs lineament and bygroundwater discharges located beneath the riverwater-level).

Groundwater discharged by the outlets in the�Cheile de Jos� gorge section of Dâmboviþa river isderived not only from infiltration occurring in thecatchment area of Dâmbovicioara stream, but alsofrom infiltration occurring within the limestonearea of the western mountain-slopes of Piatra

Craiului ridge, southward of the peak La Om(5.5 km2), and within the areas covered by sedimen-tary deposits in the catchment areas of the streamsCheia (19 km2), Ghimbav (5 km2) and of the riverDâmboviþa (10 km2 in Podu Dâmboviþei-Rucãrarea). Additionally, the indicated outlets are alsosupplied by seepage occurring in the streambeds ofthe brooks Cheia and Ghimbav, which are for mostpart supplied by runoff occurring on the crystallineterrains which provide the substratum of their up-per catchment areas.

For the karst domain of the Dâmboviþa rivercatchment area there has been plotted a variationdiagram of the effective infiltration values, whichindicated springtime maxima, followed by sum-mertime minima; however, since the surfacesbounded by positive, and respectively negativeinfiltration values were similar (175.6 mm against-169 mm), a good accuracy has resulted for thewater budget of that catchment area.

None of our observations appears to substan-tiate the occurrence of any significant hydrogeo-logical connection between the karst aquifers inthe northern part of Dâmbovicioara Passage andthe groundwater accumulations in the Braºov de-pression. We assume that such connections arelargely prevented by the occurrences of Vraconi-an-Cenomanian sandstones and of Turonian-Se-nonian shales, which transgressively overlie thelimestones.

5. Hydrogeology ofDâmbovicioara Passage

5.1. Hydrogeological characteristicsThe deposits building up the lithological as-

semblage of Dâmbovicioara Passage exhibit a widelithological diversity and they were subject to vari-ous degrees of tectonic deformations impact, cir-cumstances which in terms of hydrogeology re-sulted in various kinds of groundwater recharge,storage, and discharge, consequently leading to theidentification of 5 formation types with distinctgeological-structural and hydrogeological charac-teristics (Fig.1).

A. Thick series of Mesozoic carbonate depos-its, highly fractured and moderately karstified, dis-playing very high effective infiltration values andbeing subject to intensive groundwater flows.Groundwater accumulations occurring in this type

64

of deposits discharge through a multitude of largeflow-rate springs. This class includes carbonate de-posits occurring in the lower half of the sedimentarystack of Dâmbovicioara Passage, Hauterivian agelimestone included. Crystalline schists occurringwithin the basement provide the impervious bed forthe karst groundwater accumulations.

B. Coarse, prevalently carbonate molasse de-posits of Late Aptian age (carbonate conglomeratesand breccia), subject to groundwater flows throughfissured, porous and karst media. Surface flowsoccur only temporarily, as rainfall water is subjectto fast seepage, the latter process also supplyinggroundwater to karst aquifers hosted by the under-lying Kimmeridgian-Tithonic limestones.

C. Vraconian-Cenomanian molasse deposits(compact sandstones, polymictic conglomerates,shales) subject to groundwater flows through po-rous-fissured media. The groundwater accumula-tions supply permanent surface flows by means oflow-yield springs. In the underground, the corre-sponding aquifers are drained through karst flowsoccurring in the Kimmeridgian-Tithonic lime-stone.

D. Quaternary unconsolidated detritic depos-its (sands, gravel, occasionally clays) of reducedthickness and extent, subject to intensive ground-water flows and hosting groundwater accumula-tions of local importance. Such deposits occupyextensive areas along the main streamcourses.

E. Crystalline schists and prevalently marlydeposits, within which groundwater accumulationsare minor, or just missing. Surface flows derivedfrom crystalline terrains adjoining the passage-re-gion provide limited supplies to karst aquifers, bysinking either completely (Fundãþica, Crovului,Cheia, Raþei), or just partially (Ghimbavul,Rudãriþa). The same role is played by the crystallineschists outcrops in the central part of the passage-region (Coacãzei valley).

Piatra Craiului syncline incorporates a complexhydrogeologic structure, with groundwater discharg-ing both to the north, in the Prãpastia valley catch-ment area, and to the south, in the catchment areaof the river Dâmboviþa. The underground water-di-vide between the two indicated groundwater reser-voirs is provided by the crystalline basement upliftarea that occurs along the lineament Sbârcioarei val-ley-Coacãzei peak-La Table-La Om peak.

5.2. Groundwater outlets in Prãpastia valleyThe northern section of the aquifer hosted by

the Piatra Craiului syncline is discharging mainlythrough the groundwater outlets of Prãpastia val-ley. Those outlets occur both in Kimmeridgian-Tithonic limestones, as well as in Late Aptian con-glomerates, the latter deposits building up thematrix of the same aquifer, which had been sub-ject to a complex folding and fracturing tectonicregime.

Along Prãpastia stream, two distinct groups ofsprings occur. The first group, also known as �The6th of March� springs, is located within the mediansection of the streamcourse, to the northwest ofMãgura village (Fig. 1, no. 2). The entire ground-water discharge is tapped in closed water-intakechambers and conveyed to the town Zãrneºti, whereit is used for industrial purposes. Fluoresceine tracertests performed by T. CONSTANTINESCU in1976 have indicated that the recharge of thosesprings was partly derived from infiltration occur-ring in the catchment area of Vlãduºca brook.

The second group, known as FântânileDomnilor, is located at the downstream end of thegorge excavated by Prãpãstia stream (Fig.1, no.3)and it consists of 3 outlets having their entire flow-rate tapped for the water supply of Zãrneºti town.One outlet discharges from a small cave passageoccurring on the left side of the stream, while asecond one is located on the opposite bank and itconsits of several upflows surging from the floor ofthe water intake chamber, 3 m below the groundlevel. The third outlet, of temporary character, islocated downstream the second one.

Over the water-year X. 1979-IX. 1980, thetapped average flow-rate of the Prãpastia valleysprings amounted to 576 l/s, while contemporar-ily, the average flow-rate of the actual Prãpastiastream was 239 l/s. Over the water-year X. 1989-IX. 1990, the springs discharge has dropped to halfthe above-indicated value, while Prãpastia streamflowed only sporadically.

5.3. Topliþa water intakeAt the bottom of the northern slopes of Piatra

Craiului, in the prolongation of Topliþa fault,there occurs the water intake that bears the samename, which consists of a 300 m long draininggallery, striking N45°W and being excavated in

65

slope debris, at 5-8 m depth (Fig. 1, no. 1). Wa-ter enters the gallery through the weep holes lo-cated in its northwestern wall. The average annualflow-rate amounts to 100 l/s, while the averagewater temperature is 7.8°C.

5.4. Gâlgoaie groundwater dischargeGroundwater accumulations within the south-

ern section of Piatra Craiului syncline dischargemainly through the outlets designated as �LaGâlgoaie� and �Izvoarele din Plai�, located withinthe Dâmbovicioara stream catchment area. Thesame groundwater accumulations also contribute tothe recharge of the springs located in the �Cheile deJos� gorge section of the river Dâmboviþa.

Gâlgoaie groundwater discharge (Fig. 1, no. 6)is located in the central section of the Dâmbovicioaracatchment area, at the bottom of the right side slopeof Dâmbovicioara stream, just upstream the junctionof the latter with the brook Izvorul Uliului (950 melevation). Groundwater discharges from depositsconsisting of intensely fractured and karstifiedTithonic limestones, overlain by sub-lithographiclimestones with glauconite and by Hauterivianmarls, covered at their turn by a thick stack ofBarremian marls (Figure 4). Groundwater up-flowsalong the fault-gauge filling of the �Gâlgoaie� frac-ture zone, discharging via several outlets distributedover 5 m length, and being also accompanied by gasexhalations whose composition resembles that of at-mospheric gas. Several additional springs occur fur-ther upstream, the most significant being the one �LaBile� (Fig.1, no. 5).

Over the time-interval X.1979-XI.1980, theaverage discharge of Gâlgoaie amounted to 317.8 l/s,the corresponding minimum and maximum valuesbeing 180 and 430 l/s respectively. Over the periodApril 2003 - March 2005, the groundwater dis-charge ranged between 151 and 463 l/s, the associ-ated average flow rate amounting to 221 l/s, whilethe corresponding base flow index value (Bf=0.738)indicated that spring as being one of the most stableamong the major karst outlets of Romania.

Parameters obtained through the processingof the discharge recession curves are indicated inTable 2. The very low values (0.0016-0.0063) ofthe α recession coefficient are characteristic to frac-ture permeability karst systems, which only to asmall degree undergo the karst processes impact.The period ti during which the discharge is sub-ject to fast recession extends over a rather longtime-interval (23-49 days), this feature addition-ally emphasizing the gentle, gradual character ofthe flow rate reduction process. The groundwatervolumes flowing across the aquifer (Vdyn) are verylarge, amounting to more than 10 million m3. Thegroundwater volumes that the spring dischargesduring the fast recession period (v inf) amount toonly a very small fraction (0.18-1.68 %) of thetotal groundwater volumes (V).

Gâlgoaie spring discharges a fraction of thetotal amount of groundwater supplied by aquiferslocated in the Piatra Craiului syncline extendingwithin the Dâmbovicioara stream catchment area.In 1980, the author together with E. Gaºpar haveconducted a tracer test by injecting Br-82 tracerinto stream-losses located in the upper reaches of

Table 2. Results of the recession curves processing.

Recession no. 1 2 3 4

Time period 02.01.1980-11.03.1980

15.05.2003-10.10.2003

13.12.2003-03.03.2004

19.04.2004-20.07.2004

α 0.0063 0.0016 0.0046 0.0052

QO, l/s 300 232 242 463

Q'O, l/s 240 179 194 275

ti, days 23 49 27 30

Recession period, days 69 148 80 92

V dyn., mc 3 830 000 10 500 000 4 090 000 5 330 000

v inf., mc 6900 61 000 12 000 91 000

V, mc 3 836 900 10 561 000 4 102 000 5 421 000

v inf. (% din V) 0.18 0.58 0.29 1.68

66

Seaca Pietrelor valley, consequently outlining anunderground flow directed toward Gâlgoaiesprings, which were located 4.4 km downstreamand 325 m below the sinking point.

In 1990, another tracer test has been per-formed in cooperation with members of the cav-ing club �Hades� of Ploieºti, by releasing 80 g ofIn-EDTA in the underground stream that flowedacross the pothole in Grind (Fig.1, no. 4), a cav-ity of 540 m total depth (POPESCU G. 1988).For the next 30 days, water samples have been col-lected from the springs Fântâna Domnilor ofZãrneºti, Gâlgoaie, as well as from the riverDâmboviþa, at the downstream end of the �Cheilede Jos� gorge section, in the town Rucãr. Accord-ing to analyses performed by E. Gaºpar in theIFIN laboratories, no detectable concentrations oftracer have been recorded in the collected samples.

5.5. Izvoarele din PlaiIzvoarele din Plai are groundwater outlets lo-

cated on the right side of Dâmbovicioara stream,downstream the junction of the latter with Peºterabrook (Fig.1, no.7). The supply of those springs ispartly derived from flows sinking in the upperreaches of the brook Peºtera, and of two tributariesof the latter brook, the valleys Vopselelor andUlucelor (T. CONSTANTINESCU, 1985). Thegroundwater outlets, one permanent, amounting to60 l/s flow rate, and a temporary, over-flow one,that is located some 10 m away, discharge from theLate Jurassic limestone bedding planes. During the

drought period of the 1990 fall season, the flow rateof the permanent spring had dropped to 10 l/s.

5.6. The springs in the �Cheile de Jos� gorgesection of Dâmboviþa river

The springs are located at the southern extrem-ity of the sedimentary deposits of DâmbovicioaraPassage, close to the boundary with the crystallineterrains, in an area which displays noticeable tracesof intense tectonic deformation, where the crystal-line basement together with the Late Jurassic lime-stones are uplifted in a stepwise manner along a sys-tem of transverse-faults. Those springs occurdownstream the junction with Cheia stream, beingspread over about 2 km, on both banks of the riverDâmboviþa, both above the water level and in thestreambed.

On 28.07.1980, in cooperation with E.GAªPAR and T. TÃNASE from IFIN, a tracertest has been performed by injecting I-131 radio-active tracer in the region where Izvorului brook,a tributary of Dâmbovicioara (Fig. 1, no. 8) under-went diffuse total sinking (at 975 m elevation). Fortracer detection, filters provided with Vionit ion-exchangers have been placed in three locations - inthe upstream, median and downstream sections ofthe spring lineament. The tracer has been detectedin the groundwater discharges of the �Cheile deJos� gorge section, which were located, on the av-erage, 4250 m away and 250 m below the injec-tion point. The tracer reached the springs 60-70hours after being injected and it remained in de-

Figure 4.Hydrogeological crosssection across PiatraCraiului syncline.Legend as in Figure 1.Section line indicated inFigure 1.

67

tectable concentrations for about 160 hours after-wards, the largest amount of tracer being identifiedin the middle section of the spring lineament.

The groundwater discharge of the springs in the�Cheile de Jos� gorge section of the river Dâmboviþahas been assessed by processing the flow gauging datarecorded by the stations Podu Dâmboviþei andRucãr during periods when the hydropower reten-tion facilities were not operating, and by conductingspinner measurements at the upstream, and respec-tively downstream extremities of the springs linea-ment. Groundwater inflows have been thus assessedto range between 0.8 and 1.75 m3/s.

The karst system associated to the spring oc-currences in the �Cheile de Jos� gorge section ofthe river Dâmboviþa probably extends as far as theupper reaches of the catchment area of Ulmuluistream, and it might also discharge flows that aresinking into the swallet of ªirnea (Fig.1, no.9).

5.7. Fântâna Ulmului (Fig. 1, no. 10)On the right side of Ulmului stream, out of

a limestone cliff which displays noticeable traces ofintense tectonic deformation, a spring lineamentdischarges under drought conditions a total ofabout 15 l/s. The corresponding outlets are likelysupplied by diffuse infiltration occurring in the up-per catchment area of Grãdiºtea valley, within thegrounds of Fundata village.

5.8. The springs in Sbârciorii valleySeveral springs discharge from alluvia located

in Sbârciorii valley, close to the junction of thelatter with Coacãzei valley, in an area consisting ofa 150 m long and 40-50 m wide alluvial plain, thatoccurs at the bottom of a Late Jurassic limestonepinnacle (Fig.1, no.11). Among those springs,those designated by the letters b and d dischargethe highest flow-rates (40-50 l/s), while each of theoutlets designated by the letters a and c dischargesonly about 10 l/s. The above-mentioned alluvialplain is bounded by a gorge section: further down-stream there occurs a line of springs which areperched about 1 m above the streambed and dis-charge about 5 l/s.

On 19.09.1990, the cumulated discharge ofall those springs amounted to 125 l/s. Their re-charge is probably derived from infiltrations into

the Vraconian-Cenomanian sandstone outcrops ofthe Peºtera settlement area, as well as from waterinfiltrated in the catchment area of Coacãzeistream (which downstream the crystalline schistsoutcrops is subject to a temporary flow), and fromseepage occurring in the streambed of Ulmuluibrook, upstream its junction with Coacãzei stream.Those outlets occurrences are controlled by thecrystalline basement uplift which is situated down-stream the springs, the same structural setting be-ing also responsible for the spring occurrence(Fig.1, no.12, 10 l/s) on the lower course of Nenustream.

5.9. The spring of Uluce CaveUluce Cave is located on the left side of Cheia

stream, about 300 upstream the junction of the lat-ter with Fundãþica stream (Fig. 1, no. 13). The caveprovides the outlet for flows sinking into theRudãriþa stream swallet (Fig.1, no.14), as well as far-ther beyond that swallet, just into the streambed (I.Orãºeanu et al., 1984, Al. Bulgãr et al., 1984). Thedischarge of that outlet amounts to about 70 l/s.

Opposite to Uluce cave, a group of springsoccurring in the same Late Jurassic limestone depos-its discharge a cumulated flow-rate of 30 l/s. Unlikethe flow discharged by Uluce cave, those springswater is constantly clear and probably originates inthe catchment area of Crovului brook.

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