P37_copertina_R_OK C August 20-28,2004 Florence - Field Trip Guide Book - P37 Associate Leader:A.Vernier Leader: G.Barrocu (ITALY) THE ISLANDOFSARDINIA HYDROGEOLOGY OF 32 Volume n°5-fromP37toP54 GEOLOGICAL CONGRESS Post-Congress nd INTERNATIONAL P37 26-05-2004, 11:03:05 The scientific content of this guide is under the total responsibility of the Authors

Published by: APAT – Italian Agency for the Environmental Protection and Technical Services - Via Vitaliano Brancati, 48 - 00144 Roma - Italy

Series Editors: Luca Guerrieri, Irene Rischia and Leonello Serva (APAT, Roma)

English Desk-copy Editors: Paul Mazza (Università di Firenze), Jessica Ann Thonn (Università di Firenze), Nathalie Marléne Adams (Università di Firenze), Miriam Friedman (Università di Firenze), Kate Eadie (Freelance indipendent professional)

Field Trip Committee: Leonello Serva (APAT, Roma), Alessandro Michetti (Università dell’Insubria, Como), Giulio Pavia (Università di Torino), Raffaele Pignone (Servizio Geologico Regione Emilia-Romagna, Bologna) and Riccardo Polino (CNR, Torino)

Acknowledgments: The 32nd IGC Organizing Committee is grateful to Roberto Pompili and Elisa Brustia (APAT, Roma) for their collaboration in editing.

Graphic project: Full snc - Firenze

Layout and press: Lito Terrazzi srl - Firenze

P37_copertina_R_OK D 26-05-2004, 11:02:12 Volume n° 5 - from P37 to P54

32nd INTERNATIONAL GEOLOGICAL CONGRESS

HYDROGEOLOGY OF THE ISLAND OF (ITALY)

AUTHORS: G. Barrocu, A. Vernier, F. Ardau (Editor), N. Salis, F. Sanna, M.G. Sciabica, S. Soddu (Università di - Italy)

Florence - Italy August 20-28, 2004

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Leader: G. Barrocu Associate Leader: A. Vernier

Introduction Because of its position in the centre of the The fi eld trip focuses primarily on the hydrogeological Mediterranean, Sardinia is practically exposed to aspects of some areas in central-southern Sardinia, all winds, the northwesterly maestrale, being the taking in the coastal aquifers of the alluvial plains prevailing wind. Because of intense insolation during of Capoterra, Cagliari, Muravera and Oristano, the summer, when maximum temperature may reach and the karsts of -. The route 42°C, and wind frequency and intensity, actual comprises some of the island’s most scenic routes, evaporation is very high, often higher than potential in a succession of cliffs, beaches with wetlands and evaporation. The role of hoar frost and dew as dunes, and rugged mountains. supplementary hydrometeors in the hydrologic cycle In particular the effects of saltwater intrusion due to is still not fully understood. natural processes and especially human disturbance On the basis of mean temperature and precipitation, (river damming and mismanagement) will be Pinna (1954) has established four climatic sub-types considered. of the Mediterranean climate in Sardinia: Besides its specifi c and general hydrogeological interest, the trip will provide an opportunity 1. subtropical with a semiarid variety; to appreciate some signifi cant geological, 2. warm temperate; environmental, archaeological and historical features 3. sub-humid; of Sardinia. Sardinia is the second largest island in the 4. humid. Mediterranean (23,833 km2 or 24,089 km2 including Suspended between Europe and Africa, Sardinia the small coastal islands), and is mostly mountainous. was largely bypassed culturally, and many ancient There is only one large plain, the Campidano, which traditions survive here among its population (1.5 separates the mountains in the south-west from the million, with a density of 60 persons/km2), while rest of the island. Minor lowlands are located around only recently has the island been incorporated into the the river mouths on all Sardinia’s coasts, especially at mainstream of modern civilisation. its northwestern tip. The general relief is characterized by massifs, mostly Regional geologic setting rounded or almost fl at-topped, often separated by deep and impenetrable valleys. The highest peak Geological outline is Punta Lamarmora (1,834 m) in the Practically all the geological events of the Mountains in the central eastern part. The average Mediterranean basin, from the Pre-Cambrian to the altitude of Sardinia has been calculated at 334 m present day, are documented in this relatively small above sea level. island (24,089 Km2), with its 1,849.2 km of coastline, From a geological and hydrogeological point of a quarter of the total length of Italy’s coasts. view Sardinia may be considered one of the most Like its neighbouring island Corsica, Sardinia interesting regions in the world. In its relatively constitutes the remnant of a crustal fragment that small area, practically all the geological events of has closer geological affi nities with some parts of the Mediterranean basin are documented, from the the Iberian Meseta and of Hyeres, Provence, than Precambrian up to the present day. Almost all of the with Italy. most well known petrographical types of rocks are The crucial period was the Palaeozoic (Figure 1). represented. It was during that long era that Sardinia passed, Sardinia has a typical Mediterranean climate, not unscathed, through two great orogenies: the Volume n° 5 - from P37 to P54 n° 5 - from Volume characterized by hot, dry summers and mild rainy Caledonian, which affected Cambrian and Silurian winters. Mean annual precipitation is 780 mm, of sediments, and the Hercynian, which also affected which less than 11% is distributed in the period Devonian and Carboniferous deposits. During this June-September. Most of the yearly precipitation falls era, lithologically-varied sedimentary sequences, in the remaining 8 months of the year. Topography attaining a thickness of thousands of meters, were affects precipitation signifi cantly, annual rainfall deposited, intruded by granite then partially covered ranging from 1250 mm in the Gennargentu mountains by porphyry fl ows and fi nally by magnifi cent forests to less than 500 mm on the south-western coast. of which only traces of fossil fl ora now remain.

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu hiatuses occurred. periods oftime,althoughrepeatedsedimentary the depositionalenvironment varied littleover long was very oftenbalanced bysedimentarydeposition, over areasofvaried extent. As therateofsubsidence island nevertheless underwentprogressive subsidence Although Sardiniawas notsubmerged completely, the Mesozoic Sardiniabehaved asacratonic area. of priordisequilibrium.ContrarytothePalaeozoic, only affected byisostaticadjustmentasaconsequence phase oftheHercynian orogeniccycle, the islandwas was partofarelatively stable platform. After thefi Cambrian sedimentscropout.InMesozoictimes,it Sardinia istheonlyregion inItalywheretheearliest Figure 1-Geologicalsketch mapofSardinia. nal geological events necessarytounderstandtheearliest makes itdiffi The overlapping oftheeffects ofrepeatedorogenies nearby regions have beeninvolved init. subsequent Alpine orogeniccycle, even thoughvast which hasbeenalmostorentirelyunaffected bythe present comprisethesedimentaryandvolcanic cover units fromtheUpperCarboniferous-Permianto and theHercynian orogenies. The lithostratigraphic Carboniferous, was affected byboththeCaledonian Palaeozoic formationsfromtheCambriantoLower the basement,consistingofpre-Cambrianrocksand region. This seemstobethecaseinSardinia.Here none oftheorogenicphenomenaaneighbouring becomes morestable,orcratonic,laterexperiencing history, aregion atfi relative orogeniccalm.Duringitslonggeological short sedimentaryhiatusescorrespondtoperiodsof modifi phases ofanorogeniccycle andthegeodynamic of transgressionandvolcanism indicatethevarious transgressions, thefewer thehiatuses. The phenomena others. For instance,thegreaterandlongerlasting of thesephenomenavaries ininverse proportionto can change(Figure2).Insomecasestheintensity earth’s crustandtheboundarybetweenearthsea hiatuses prove towhatextent theconditionsof Transgressions, discordancesandsedimentary Tectonics from thatoftheItalianpeninsula. history ofthisregion hasevolved quitedifferently the coast.Itisevident thatthemostrecentgeological traces ofUpperPleistocenemarinedepositsalong sediments remaininginSardiniafromthetimeare signifi western partoftheislandthatunderwentmost During theCenozoic,asinMesozoic,itwas the to reappearmoreextensively throughouttheMiocene. covered partofthearea,retreatinginOligocene, transgression duringtheLower Eoceneonceagain of localportionstheearth’s crustsothatmarine its cratoniccharacter, withonlyvertical oscillations Campidano andCixerri. The Mesozoicareapreserved deepening somegrabens,suchasthoseofthe permitting effusions ofcalc-alkalinemagmasand that deformedtheMesozoicsedimentaryrocks, minor movements ofthe Alpine orogeniccycle orogenic cycles, theislandwas stillaffected by In fact, longaftertheCaledonianandHercynian considered amilderrepetitionofprecedingevents. Sardinia’s mostrecentgeologicalhistorymaybe cant paleogeographicalchanges. The only cations consequenttoit.Ontheotherhand cult torecognisethegradualchangesin rst clearlyorogenicgradually 26-05-2004, 11:09:21 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

phenomena.

The chronology of the tectonic phenomena may be summarised as follows:

The Caledonian Cycle Sedimentation in subsiding basins with “external” and “internal” characteristics probably with an intermediate ridge roughly north-northeast of the Campidano graben. This ‘ridge’ presently trends northwest-southeast. Compressive and distensive tectonics were active with an east-west polarity. Initial volcanism was acidic (rhyolitic and rhyodacitic), and subsequently (?) basic (diabase, spilites, etc.). Finally metamorphism was followed by “granitization”.

The Hercynian Cycle The Hercynian cycle was represented by an intermediate massif between two antithetic orogenies (Variscan to the north and Maghrebian to the south), roughly corresponding to the molassic areas of limited subsidence of the Caledonian cycle. Sedimentation occurred both along and laterally to the dorsal ridge separating the two troughs formed during the previous cycle. The tectonism was compressive and distensive. Essentially “late” tectonic granites were emplaced at the end of the “molassic” sedimentation. Acidic, Figure 2 - Synthetic structural sketch map of Sardinia basement. 1: Post-Hercynian sediments and volcanites; (rhyolitic and rhyodacitic) and basic (andesitic) 2: Granitoids; 3: Very low (south-west Sardinia) to low- volcanism occurred. grade metamorphites; 4: Main orthogneiss outcrops; 5: Intermediate pressure amphibolite facies metamorphites; The Alpine Cycle 6: Intermediate-pressure amphibolite facies migmatites Triassic-Eocene: The mainly crystalline Palaeozoic containing nodules and lenses of rocks bearing relics of basement formed a platform. Local sedimentary granulitic and seldom eclogitic parageneses; 7: Major and Mesozoic covers are varied and discontinuous due minor overthrusts; 8: Hercynian cover; 9: Pre-Hercynian basement (?) (Carmignani et al., 1986). to limited local subsidence. Lack of magmatism is apparent. orogenic activity; Oligocene-Quaternary: During the Oligocene- b) Deposition in the eastern zone diminished from the Quaternary the formation of molassic troughs was Dogger to the Tyrrhenian. The eastern zone behaved related to external Alpine troughs. The Oligo-Miocene in a rigid manner and appears to have been affected and Pliocene tectonic cycles evolved independently. by the Alpine orogeny as attested to by repeated faults The formation of troughs was accompanied by and dislocations, which also extended into the nearby intense, continuous magmatism. There was a lack of area of the ;

compressive tectonics during the entire cycle, but the c) The western zone, apart from the graben areas, P37 to P54 n° 5 - from Volume individual epeirogenic belts of north-south alignment was affected in a rather plastic manner by the (each with its own evolutionary sequence) may be vertical movements of the crust. These movements summarised as follows: were represented by repeated marine transgressions a) The central zone was relatively stable, having been and were responsible for the accumulation of thick submerged for a short time during part of the Middle continental deposits in the graben which formed and Late Jurassic and possibly in the Early Eocene. during the Alpine orogeny. This subsidence apparently conformed to transverse alignments which were predetermined by earlier

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu known thermalsprings,characterized byahigh of waters reappearonthesurface issuingfromwell at depthbyfreshsurface waters. Thus, thesetypes the mostimportanttectoniccontacts,aremobilized mobilized bycirculatingfl saturated theimperviousrocksandispresentlyre- especially duringtheQuaternary. Marinewater variations duringtheisland’s geologichistory, The originofsalinityismainlyduetosealevel relatively faster (Zuppietal.,2003). movement iscontrolled insteadbygaspressureandis Nativ, 1994),governed bypiston fl represented asamulti-cellsystem(Mazor& well. Downward movement couldbeschematically sedimentary basinsbut occursincratonicareasas deep fl take partinthesteam-rockinteractionatdepth. Thus, In fact, palaeomarineconnatewaters alsocontroland as seawater level rose,dependingonclimatechange. pores ofsomelow permeabilitybedrockformations groundwater, likely trappedinunleachedfracturesand then pushedupwards andalsomixed withconnate At depth,groundwater becomesheatedandis along siphonfracturesactingasconduits. as itpercolatesdown andisthenforcedupwards the area.Groundwater becomesincreasinglyheated through theintensive faulting oftherocksthroughout At present,groundwater recharging takes place bedrock complex (Zuppietal.,2003). portions offault systemsorfracturedzoneswithinthe phenomena, relatedtotheriseofdeepfl thermal springsintheareacorrespondtovery local methods andisotopicstudiesclearlyshow that geoelectric, magnetic,electromagnetic,andseismic Geophysical investigations withgravimetric, 2003). depending onlatevolcanic phenomena(Barrocu, their deepcirculationortogeothermalanomalies is dueeithertothegeothermiceffect associatedwith cool waters fromtheupperaquiferlevels. Their heat as indischarge areashotwaters becomemixed with and wells,but generally theirtemperatureismoderate Locally, deephotgroundwater issuesfromsprings formations inupfaulted anddownfaulted blocks. the Palaeozoic crystallinebedrockandoverlaying along themajortensionandshearfracturesdissecting interconnected. Watersinfi be identifi structures. Deepandshallow aquifersmay and thisisclearlyrefl The geologicalfeaturesofSardiniaarevery complex Hydrogeology uid circulationisnotonlypeculiaroflarge ed, thoughthey areoftenlocally ected initshydrogeological ltrate andcirculateatdepth uids. Brines,replenishing ow. The upward The ow. uids along uids selective electrodeandcolorimetrictests)HCO selected stableisotoperatios( phases, afew minorandtraceelementsaswell parameters, majorelementswithingaseous andliquid consideration physico-chemicalandenvironmental survey was carriedoutinSardinia,takinginto From FebruarytoJune1997,afl tritium freeandwithavery low carbon-14activity. sodium–chloride content,depletedinoxygen-18, electrical conductivity, pHandEh),dissolved Physico-chemical parameters(temperature, or jeopardizedbysaltwater intrusion.Ontheonehand observed incoastal areas,almosteverywhere affected deposits. The effects ofover-abstraction aretobe to alesserextent, byvolcanic formations andalluvial represented primarilybyMesozoiclimestones,and, Major aquifersbeingexploited formunicipaluseare yet totallysatisfactory. mainly formunicipaluses,even iftheresultsarenot table increased,andfreshwater isnow withdrawn, since miningactivities have ceased,hasthewater enable miningoperationstoproceed.Onlyrecently, concentration, H m on it,tosuchanextent thatatotaldischarge of1.75 water tablewas drawn down andseawater encroached excavated down to-200m.Consequently, thefresh was stronglyincreasedasshaftsandtunnelswere mining activities inthecoastalarea,andpermeability variations. Groundwater circuitsweredisturbedby on thedifferent orogenicphasesandsealevel (down toseveral hundred m),instagesdepending were fracturedandstronglyaffected bydeepkarst Throughout theirlongevolution, thelimestones district ofIglesias(southwesternSardinia). Cambrian limestonesintheleadandzincmining represented bythelarge aquifer systemofMiddle In thePalaeozoic basementoneexception is are affected byseasonalrainfall variations. than 100m.Suchaquifersmostlyhave pooryieldand boreholes afew tensofmetersdeep,generallyless issues fromanumberofspringsoristappedthrough the upperfracturezonesofbasement,andeither Of course,freshrecentgroundwater circulatesin thermal-mineralized, coldspringsandwells. Graben. A numberofsitesweresampled,including area,the Tirso Valley andtheCampidano fault systems:fromNtoS,theCasteldoriaarea, the islandwereconsidered,alllocatedalongregional fi concentration (bytitration)weredeterminedinthe eld. The water-dominated hydrothermalareasof 3 /s ofbrackishwater neededtobepumpedoff to 2 S concentration(byORIONion- 2 H, 18 O, ud geochemical uid 13 C). 26-05-2004, 11:06:59 222 Rn 3 -

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thousands of wells have been drilled along the coast The imposing remains of the ancient Punic city’s line, at a distance smaller than the radius of infl uence necropolis on the Tuvixeddu hill are now being of their total drawdown, on the other the surface runoff restored. Occupied by the Romans, the ancient of major rivers has been dammed upstream so as to Karalis had its Castrum (castle) in the Marina district, meet the increasing water demand. Therefore, fl oods and spread out, above all, onto the plain between the have drastically diminished downstream and no longer hills and the sea. In addition, in the late Middle Ages, recharge delta aquifers as before. Considering present the town, called Santa Igia, was built near the S. uses, groundwater resources may be conservatively Gilla lagoon. Later the Pisans raised a line of defence estimated at 150÷200 hm3, of which about 50 hm3 around the limestone hills dominating the gulf. Only are distributed through aqueducts for domestic water the Pisans were entitled to spend the night in the supply. Annual surface runoff averages 6,100 hm3, Castello district. Cagliari, for all Sardinians, became of which up to 1640 hm3 are used in a system of 38 Casteddu. Conquered after a siege by the Aragonese in reservoirs to meet major water demand for domestic, 1326, it became the capital of the Regnum Sardiniae agricultural, and industrial purposes. (). Today the old city lies between the port and the Field itinerary Marina district, with the Stampace district to the west, DAY 1 and the Villanova district to the east, at the foot of the cathedral, the white towers of the central Castello Stop 1.1: district overlooking them. Cagliari, the Capital of the Autonomous Region of The visit starts from Via Roma, in the Marina district, Sardinia, is situated in the middle of the Golfo degli with the imposing Palazzo Comunale (Figure 4) and Angeli (Gulf of Angels), bordering the southern part the parish church of S. Eulalia. of the Campidano Graben between the tectonic blocks of the Sulcis, to the west, and Sarrabus, to the south. The most signifi cant morphologic feature are the ten hills, that though not particularly high (140-60 m), clearly emerge with their trapezoidal profi le from the fairly fl at zone just a little above sea level. The hills are tectonic blocks composed primarily of sub-horizontal benches of terrain of the transgressive Miocene sandstone- limestone series. The low hillslopes, where the lower arenaceous strata of the series crop out, are for the most part gently sloping, while the largely fl at hilltops, composed of benches of calcarenites and biohermal limestones, often have vertical or sheer walls, generally coinciding with fault planes or disused quarry faces. The original morphology has been P37 to P54 n° 5 - from Volume transformed by human activities, as the hills were quarried for building materials from ancient times up until a few decades ago. Figure 3 - Map of the historic centre of Cagliari. Cagliari (Figure 3), once called Karalis, was founded in the 6th century BC by the In the Stampace district, that was, from the Middle Phoenicians, who created a commercial port of call Ages, a residential enclave, are the churches of S. within the S. Gilla lagoon. Anna and S. Michele. In the Villanova district, at

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu Royal Arsenal was built. Itwas latertransformedinto out inordertoimprove thedefencesystemand artillery’s evolution. In1800otherworks werecarried in 1573fordefencepurposesandfollowing the tanks excavated inthelimestone.Itwas transformed Punic andRomanages,asevidenced bytwo water the areahasbeeninhabitedsincePhoenician- Cittadella was built in1552underSpanishrule,but Archaeological Museum,isworth avisit. The complex), withthe Art GalleryandtheNational Arsenale, theCittadelladeiMusei(themuseum Quite closetothedistrictofCastello,inPiazza island. one ofthemostimportantRomanmonumentson Pomptilia; theRomanamphitheatre(2ndcentury AD) excavated inthelimestonerockhonourof Atilia the “grottadella Vipera”, abeautifulRomantomb are theRoman Tigellio villa,(1stcentury AD); houses numerousworks ofart.Inthenewer districts the 1200s,andthenextensively modifi Maria, onceasignifi former royal palaceoverlooks, isthecathedralofS. gothic monument.InthePiazzaPalazzo, whichthe The churchofthePurissimaisaninterestingCatalan Mediterranean. the mostbeautifulmedieval militaryworks inthe by theSardinianGiovanni Capula,areamong 1307, andthetower ofS.Pancrazio (1305)built The Elephanttower (Figure5)whichdatesto precious architecturalmonumentscanbeadmired. In thedistrictofCastello,somecity’s most Bastion. from piazzaCostituzioneonecanseetheSaint-Remy and S.Giacomoareworth avisit,whilelookingup the footofCastello,churchesS.Domenico Figure 4-Town hall. cant Pisanbuilding datingfrom e, which ed, architecture ofnationalinterest.Itre-openedtothe Saturno (Figure6),isafi The Paleo-Christian andRomanesquechurchofS. black paintedpottery. the emperorsNero’s and Trajan’s portraitsandthe suggestive isalsothereplicaof Tharros “tophet”, important artefacts fromtheNuragic Age. Highly the Bronze Age canbeadmired,aswellother In particular, fi early Middle Ages. antiquities datingfrompre-historicaltimestothe The National Archaeological Museumhouses structure began in1965andwas completedin1979. it was abandoned.Constructionwork ofthepresent In 1943bombingsdestroyed thewholestructureand a militaryzone. To fi To public in1996after18yearsofrestoration. To theeastofCagliari,Molentargius lagoon, important churchontheisland. and fi 1326 inCatalangothicstyle,thelatter1700s, basilica ofBonaria(Figure7),theformerbuilt in nish, facing thesea,aresanctuaryand nished aftertheSecond World War. Itisthemost nds fromtheNeolithicand ne example oflatemedieval Figure 5–ElephantTower. 26-05-2004, 11:09:45 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

consisting of two basins with different salinity, is separated from the sea by the Poetto beach, a 15 km long stretch of sand bordering the plain between the hills of the Castello and the highlands of the Sarrabus tectonic block. Its varied wildlife, protected by the Ramsar International Convention, makes

Figure 8 - Poetto beach, salt-flats and Molentargius lagoon.

natural area of major environmental interest, separated from the sea by the Giorgino beach, a narrow strip of sand, named after the old Church of Giorgino, and dominated by the Quarta Regia tower. Figure 6 - Church of S. Saturno. The extensive Santa Gilla lagoon has traditionally provided an endless source of fi sh for the people the Molentargius lagoon one of the most important of Cagliari. Unfortunately, the surrounding area is wetlands in Europe. Some two hundred species of today partly altered by road infrastructures, industrial birds inhabit the lagoon, including pink fl amingos. premises and the new container port and canal, and In 1993 a few hundred pairs of fl amingos chose a is threatened by pollution. Nevertheless, fl amingos tranquil corner of the lagoon to nest and reproduce, continue to inhabit the lagoon, one of their preferred and it has now become their permanent home, under homes. the watchful eyes of tens of thousands of Cagliari’s In the middle of the Gulf of Cagliari, the Poetto and residents. All around the lagoon, really spectacular for Giorgino beaches are bounded by the promontory of its beauty and vastness, all activities such as hunting the block of the Sella del Diavolo and Capo S.Elia, and fi shing are prohibited. from where one can admire the magnifi cent panorama The Poetto beach (Figure 8) is easily reached in a few of the entire gulf. To the west the extreme tip of Capo minutes from the city centre, and lies opposite the Carbonara, and Villasimius, to the east the coast of Molentargius lagoon, enclosed by the Capo S. Elia. Pula with the ruins of Nora, the ancient Phoenician Because of its shape, the summit of this headland is capital of Sardinia. called the devil’s saddle, Sella del Diavolo. The S. Gilla Lagoon, to the West of the city, is a Stop 1.2: From Cagliari to the Natural Monument “Arco dell’Angelo” (50 Km). General information on the itinerary The route proceeds along the SS 125 main road climbing up and down winding bends through the characteristic landscape of the Sette Fratelli (Seven Brothers) hills. P37 to P54 n° 5 - from Volume

Recommended Maps Topographic maps –IGM tables 1:25,000, series 25: 557 sect. II Quartu S’Elena, 558 sect. III Castiadas and IV Burcei. Geological maps – Sheet 1:100,000: 234 Cagliari. The scenic route from Cagliari to Muravera follows Figure 7 - Basilica of Bonaria. the gorges cut by the Rio Picocca and Ollastu in the

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu destination forhikers, andtheSerpeddìmountains. main road,throughtheSetteFratellipark,afavourite be reachedbydriving alongthepicturesqueSS125 built upareasbeing Muravera andCastiadas,can The region hasalow populationdensity, themain mid 1900stoletheavy vehicles through. monument (L.R.31/89),whichwas demolishedinthe the “Angel Arch” canbeseen,classifi State lands. Along theroutenaturalarchknown as bush andconifer stands plantedforreforestationof a variety ofplantspecies,includingMediterranean The Sarrabus is an extensive naturalareahometo can beobserved. postcrystalline tension,shearandoverthrust fractures affected bydifferent systemsofprecrystallineand of lamprophyre,aplite,andmicrogranitedikes, and structure ofthegraniteblock,crossedbyswarms granite tectonicblockoftheSarrabus. The intimate As shown inFigure9,thegeologyof the deltaplain Geology andhydrogeology evolutionary trends. environmental conditionoftheaquifersandpossible on. Inthiscontext, themainproblemsrelateto as industry, agriculture,fi terms ofhumansettlementsandrelatedactivities such sea. Ontheother, thecoastalplainsareattractive in maintain theequilibriumbetweenfreshwater andthe and confi and more-or-less permeablesedimentshostphreatic signifi vulnerable areasbecauseoftheconcurrenceseveral environmental risk,coastalplainsareamongthemost major environmental interest. As known, intermsof aquaculture alongthecoast. The areaisalsoof relies heavily onagricultureaswelltourismand second largest river. The economyofthearea was formedbytheRiver Flumendosa,theisland’s The Muravera coastalplain,insoutheasternSardinia, Geological MapofItaly1:50.000:549Muravera. Geological maps 558 sect.ISanPriamo,549IIMuravera. Topographic maps–IGMtables1:25,000,series25: Recommended maps Cannas andPicocca. gradually becominglesswindingalongtherivers The routeproceedsalongthesameSS125mainroad General Information ontheitinerary From the Arco dell’AngelotoMuravera (30Km) Stop 1.3: cant factors. Ontheonehand,unconsolidated ned aquifers,rivers andlagoons, –Sheet1:100,000:227Muravera, sh farming, tourism,andso ed asanatural understood byhydrogeologists. stratigraphy oftheconfi tens ofmetersthick. The lower boundaryanddeeper from theformerbyaclaylayer, fromafew toseveral an undefi aquifer extending down toafew tensofmeters,and two aquiferscanbedistinguished:ashallow phreatic alluvial deposits. To date,thedominanttheoryisthat cooler months,groundwater ishostedprimarilyinthe which afew smallephemeralspringsissueduringthe occurring inthefracturedPalaeozoic rocks,from from thesurroundinghills. Apart fromthewater seawater, andseveral seasonalstreamsfl connected withtheriver itselfbut containincoming its channelsattheriver mouth,whicharenolonger The surface water bodiesaretheFlumendosaRiver, the basisofmorphologyandsurface geology. the metamorphiccomplex hadonlybeenestimatedon the thicknessofrecentalluvium,ancientand village ofSan Vito. Beforeourgeophysicalsurveys, Figure 9,cropoutafew kilometersnorthofthe Carboniferous- Permian),whicharenotshown in overlying thePalaeozoic bedrock.Granites(Upper and alluvium,uptoafew hundredmetersthick, the plain,andPleistoceneHolocenesediments metamorphic complex croppingoutontheedgesof and itssurroundingsischaracterizedbyaPalaeozoic metacalcarenites andmetalimestones;8.metasandstones Holocene: 1.beach deposits;2.eolian3.recent Silurian: 6.carbonaceousshales.UpperOrdovician: 7. and whiteporphyriticrocks. MiddleCambrian-Lower alluvium; 4.talus.Pleistocene:5.terracedalluvium. and metaconglomerates.MiddleOrdovician: 9.grey Ordovician: 10.metasandstonesandmetasiltstones Figure 9-GeologicalmapoftheMuravera plain. ned, deeper, confi ned aquiferarestillpoorly ned aquifer, separated (Balia etal.,2003). owing down owing 26-05-2004, 11:07:25 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

In the Muravera plain the natural hydrodynamic equilibrium between surface fresh waters and fresh groundwater and seawater is extremely critical. Other than by natural phenomena, such as recurrent drought, this equilibrium has been altered since 1950 by upstream dams and river engineering on the Flumendosa that have diminished natural recharge to the coastal aquifers. The problem is compounded by increasing, uncontrolled exploitation of groundwater for irrigation in the summer. This has resulted in seawater intrusion and progressive groundwater and soil salination, initially observed in the phreatic aquifer. Groundwater quality monitoring over the past two Figure 10 - Water conductivity map of the phreatic decades has produced evidence of seawater intrusion aquifer in June 1999. Contour line labels in µS/cm (Ardau, 1995). In particular, monitoring of the phreatic (Balia et al., 2003). aquifer, which began in the ‘80s (Ardau & Barbieri, 1994; Ardau et al., 1996, Barbieri & Barrocu, 1984), indicates progressive saltwater encroachment inland. In June 1999 we conducted water level and salinity measurements in order to assess groundwater salination (Ardau et al., 2000). The shallow aquifer, (Figure 10) shows electrical conductivity, which is indicative of salinity, of as much as 2000-8000 µS/cm with several peaks of over 20000 µS/cm between the seashore and the town of Muravera. In this regard it should be noted that 2000 µS/cm is the maximum permissible conductivity for many crops, and that the optimum value for drinking water is about 400 µS/cm. Figure 11 - Water conductivity map of the confined Similar conditions have also been observed in the aquifer in June 1999. Contour line labels in µS/cm deep aquifer, as shown in Figure 11. (Balia et al., 2003).

Main studies (1983-2002) hundred meters away from the centre of VES9 (Figure Studies in the Muravera coastal plain were resumed in 12). Our drilling facilities allowed to reach a depth of 1983-2002, with: no more than 35.5 m, since at 32.7 m we came across - piezometric, chemical and physical monitoring a harsh gravelly-sandy layer containing high pressure throughout the network; saltwater and were forced to interrupt drilling - surface water level and quality monitoring; operations. However, the stratigraphy obtained - exploratory drillings; proved rather meaningful. - conductivity and temperature well logs; In terms of the hydrogeological model and salination - vertical electrical soundings; status, the results were interpreted as follows. The Volume n° 5 - from P37 to P54 n° 5 - from Volume - gravity surveys; fi ndings confi rmed the phreatic aquifer is separated - refl ection seismics. from the underlying confi ned aquifer and, also for this reason, they very likely have rather different histories. Recent developments The phreatic aquifer is actually affected by saltwater In order to arrive at an interpretation consistent with intrusion whose present evolution is dependent upon the real geological and hydrogeological conditions, several factors, such as overexploitation, upstream we decided to drill several calibration boreholes dams, recent artifi cial channels that have been opened (Balia et al., 2003). The fi rst borehole (BH1) was for fi sh-farming, and recurrent drought. On the located at the fi rst seismic line (SP1), less than a

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Volume n° 5 - from P37 to P54 P37 - P37 locations (Baliaetal.,2003). Figure 12-ResistivitysectionandseismicprofileSP1 Leader: G.Barrocu borehole hadtobedrilled. This boreholewas drilled to combineitsinterpretationwithgravity, atleastone the secondseismicsectionpreviously acquired, and In ordertovalidate thegeological interpretationof seawater. not correspond,oratleastexactly, topresent-day mean thatthesaltwater oftheconfi layer, whichdiffers signifi contained inthedeepaquifer, beneaththeclayey the seawater, thisisnotthecaseofgroundwater shallow aquiferpresentssimilarcharacteristicsto (2000) showed thatwhilethegroundwater inthe investigations carriedoutby Ardau andBarbieri until recently, and,second,that recenthydrochemical a deepaquiferwhichhasnotbeenheavily exploited that saltwater encroachmentisnotactuallyjustifi interpretation isalsosupportedbytwo factors: fi to bygeologicalstudies(e.g.Barcaetal.,1981). This kilometres inlandfromitspresentposition,asattested ancient past,whentheseashorewas situatedseveral likely isrelatedtovicissitudesthatoccurredinthe to beattributable toquitedifferent causes.Itmost other hand,salinationoftheconfi cantly fromit. This could ned aquiferseems ned aquiferdoes ed in rst, Pleistocene alluvium,whichvery likely coincides the interface betweenHoloceneandimpermeable of theinformationconsideredessential,suchas information areavailable, thissectioncontainsmost southernmost part,wherebothgravity andseismic 13, whichisnotonlyqualitative. At leastinthe was possibletodraw the geological sectioninFigure boreholes BH2andBH3,thesurface geology, it Finally, fromourgeophysical results,aswellfrom corresponding tounit10inthelegend ofFigure9. grained, siliceousmetasandstonesandmetasiltstones confi of 35.6m.Petrographicanalysesonsamples This reachedthemetamorphicbasementatadepth borehole, BH3(Figure13). northwards alongthesameprofi gravelly layers,wemoved several hundredmeters metamorphic basementwithoutinterferingwith information. Thus, inthehopeofintercepting terraced alluvium,whichinitselfwas very useful encountered. This layerwas identifi alluvium cementedbyareddishclayey matrixwas drilling atadepthof42m,wherelayergravelly of nomorethan80-100m. Again wehadtostop so astointerceptthemainrefl (BH2) inthemiddleofsecondseismicline(SP2), rmed thatthesemetamorphicrocksarefi ectors drillingtoadepth le, anddrilledanother ed asPleistocene 26-05-2004, 11:07:31 ne- HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

with the lower boundary of the confi ned aquifer, the Rio Pardu-Pelau departs, an example of entrapment. thickness and distribution of Pleistocene alluvium, and the structure and composition of the Paleozoic On the summit of the western block, transgressive basement. on the Palaeozoic bedrock, are the peaks of the cover Worthy of note are the extensive Foce Flumendosa, made up of the Jurassic conglomeratic-calcareous- San Giovanni, Saline and Colostrai beaches. Beyond dolomitic series and of the conglomeratic-arenaceous-

Figure 13 - Quantitative geological section inferred marly-calcareous-arkosic series of the Eocene from geophysical data: 1. soil and Holocene deposits; 2. M. Cardiga plateau. The limestone and dolomitic Pleistocene terraced alluvium; 3. Middle Cambrian-Lower limestone strata of the two formations are signifi cantly Ordovician metasandstones and metasiltstones; 4. Upper karstifi ed at depth and form major aquifers. Carboniferous-Permian granite; 5. fault (Balia et al., 2003). The Jurassic aquifer, one of the largest in Sardinia, the Colostrai beach lies Capo Ferrato, a headland of supplies drinking water to a number of towns and trachytic rocks. Further south the Costa Rei beach villages in central-eastern Sardinia, often situated at stretches for 8 km (Figure 14), with its holiday homes. the foot of the walls delimiting the formation, along Nearby are a number of interesting archaeological the line of springs in contact with the impermeable sites, in particular the menhir at Piscina Rei and Cuili schist bedrock. Piras. Beyond the River Flumendosa, the tectonic valley Stop 1.4: that formed on the Villasalto overthrust, creates an From Muravera to (65 Km). anomalous contact between the pre-Hercynian and Silurian-Devonian schist-crystalline series. The E- W trending fault, that crosses the whole Sarrabus Figure 14 - Costa Rei. region from W to E and likewise the concomitant faults that accompany it northwards, are intersected by minor faults trending on average NW- SE, with small vertical throw and horizontal throw that attains 4 km near San Vito.

Climbing northwards up the Rio di P37 to P54 n° 5 - from Volume Quirra-San Giorgio tectonic valley, dominated by a block of Silurian limestone, on whose crest rise the ruins of the Medieval Castle of the Marquise of Quirra, ruler of the feudal estate, we proceed up to the Genna Cresia saddle, from which the tectonic valley of the

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu a dirtroad,onecanvisitthe Astronomic Observatory. and MonteFerruat . At thetop,accessibleby views ofthewholeOgliastraregion asfar asthesea Ceresia andPunta Tricoli, whichoffer breathtaking Wonderful excursions canbetaken uptoMonteSa remains ofaNuragicvillagearetobefound. Along theroadtoGairoisSeleneforest,where urban landscape. domed Temple ofS.Giovanni Bosco dominatingthe charming cathedralofS.MariaMaddalena,andthe sloping down tothesea. We suggestavisittothe side ofasteephilloverlooking amagnifi Lanusei, thesmallcapitalofOgliastraisbuilt onthe boar, mostlyintheinterior. including vultures,birdsofprey, mouffl Numerous speciesofanimalsinhabitthearea seals whichtodayareindangerofdisappearing. Grotta delBueMarino(seacow’s cave), oncehometo One ofthemostwellknown andpopularspotsisthe wild fl its contribution toconservation ofnaturalhabitatsand SCI (SiteofCommunityImportance),bytheEUfor In fact theentireOroseigulfhasbeendesignatedan are todayallvery well-known touristresorts. admired: CalaGonone,Luna,Goloritzè, the mostbeautifulbaysofMediterraneancanbe plains. Sailingalongthismagnifi drop sheerintothesea,age-oldwoods anddrydesert beaches, crystal-clearwaters, imposingcliffs that The entireOgliastraregion boastsfi Muravera, 541Jerzu. 219 Lanusei.GeologicalMapofItaly1:50.000:549 Geological maps–Sheet1:100,000:227Muravera, sect. II Tertenia andIJerzu,531sect.IILanusei. 549 sect.IIMuravera andICastellodiQuirra,541 Topographic maps–IGMtables1:25,000,series25: Recommended maps stretch oftheSS125mainroad. The routeproceedsalongamore-or-less straight General Information ontheitinerary Topographic maps Recommended maps The routeproceedsalongthepaved road. General Information ontheitinerary From LanuseitoSantaMariaNavarrese (35Km). Stop 2.1: ora andfauna. –IGMtables1:25,000,series25: DAY 2 cent coast,someof ne whitesandy ons andwild cent valley cent today plasteredwithcement. offi another storey was built ontotheterraceforuseas During restorationwork carriedoutinthemid1800s a 12-m-diameterbaseandwas originally10mhigh. the 1500s,tower, withitstruncatedconeshapehas between 1785and1790onaformerlookout postof Navarrese thatdominatesthebeautifulbeach.Built trees, anancientwellandthe Tower ofSantaMaria the churchareagroupofthousand-year-old olive landed onthecoastafterbeingshipwrecked. Near one ofthedaughtersKingNavarra, who Legend hasitthatthechurchwas built byIsabella, church ofthesamename,modifi its marinaontheBauneicoast,standsaXICentury In thecharmingvillageofSantaMariaNavarrese with Geological maps di MonteSanto. 531 sect.I Tortolì andIILanusei,548sect.IIICapo Gulf ofOroseiisdottedwithenchantingbeaches- Martine, withitssheercliffs andwooded slopes. The accessible viaapanoramicroad,thestony CalaZiu the BueMarinocave, beyond CalaFuilswhichis myriad naturalmarvels: totheSouthCalaGonone crystal clearwaters ofthe Tyrrhenian Seacreates The extraordinary blend ofaustererocksandthe in theterritoryofDorgali andneighbouringvillages. Cretaceous limestoneplateautowering above thesea This istheSupramonte,animposingJurassic- reserve fortheprotectionofmonkseal. which nestlesCalaGonone,istodayamarinenature be visitedbyboat. The Gulf ofOroseiinthecentre Sardinia, theentirecoastwithitsenchantingcaves can miles northoftheport ontheEastcoastof From theSantaMariaNavarrese marina,2.5nautical 208 Dorgali. Geological maps Cantoniera GennaSilana,500sect.IIDorgali. 25: 548sect.IIICapodiMonteSanto,547I Topographic maps Recommended maps from theS.MariadiNavarrese marina. The trip,aboardmotorboatsorlarge dinghies,starts General informationontheitinerary of . From SantaMariaNavarrese tocoves alongtheGulf Stop 2.2: ces. The originalwalls, probablyinlimestoneare –Sheet1:100,000:219Lanusei. –Sheet1:100,000:219Lanusei, – IGM1:25,000tables,series ed inthe1950s. 26-05-2004, 11:07:39 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

Cala Luna, Cala Sisine, Cala Biriola, Cala Mariolu, the rare pinnipeds used to seek shelter to give birth Cala Ispiuligidenìe, Cala Goloritzé (Figure 15) to their young and to rest. No words can describe the (beneath the 100m high natural pinnacle known as spectacular secrets of this fascinating underworld. Aguglia) which interrupt the rocky coastline up to Seven kilometres from Cala Gonone marine 3 km Capo di Monte Santu. South of the Bue Marino cave, is Cala Luna, a The coastline forms the seaward boundary of the paradise not to be missed by tourists travelling to the and also delimits the area designated to become the National Gennargentu Park. Stop 2.3: From the coves of the Gulf of Orosei to Cala Gonone. General information on the itinerary The route continues by boat or large dinghy to the Cala Gonone marina.

Recommended maps Topographic maps – IGM 1:25,000 tables, series 25: 548 sect. III Capo di , 547 sect. I Cantoniera Genna Silana, 500 sect. II Dorgali. Geological maps – Sheet 1: 100,000: 219 Lanusei, 208 Dorgali.

Cala Gonone is renowned above all for its fascinating boat trips. A very well- organized boat service, Figure 15 - Cala Goloritzé. which fi rst started in 1954 when the Bue Marino caves were opened to the public, ferries tourists the region. In the summer a boat service runs 4 km along the coast from the harbour to the caves a regularly between this beach, and also to Cala Sisine, little further on from Cala Fuili. The caves are visited and Cala Gonone (refreshment kiosk on the beach). by tens of thousands of tourists each year. Cala Luna has been described as the Mediterranean’s Beyond the impressive entrance, recognizable by its most beautiful beach. Six huge caves open out onto gigantic column, the cave divides up into a fossil it and the coastal lagoon is fringed by oleanders. At part (north branch) and an active part (south branch), the southern end Punta Su Masongiu (115 m), a high

where the seawater mixes with the freshwater spilling wooded rocky cliff that shelters the crescent moon P37 to P54 n° 5 - from Volume from the innermost parts of mountain. This part, now bay from scirocco (warm, southerly) winds. lighted and opened to the public in 1983, is studded Equally attractive is the coast north of Cala Gonone. with concretions, stalactites and stalagmites that The stretch of coast between Cala Luna and Pedra refl ect in the crystal clear pools. The tour fi nally Longa has been designated a protected area for brings us to a large cavern in the middle of which the safeguard of the monk seal and access to and is a stalactite column and, at the back, a wide beach navigation in this part of the coast is restricted. (known as the seals’ beach) where, up to the 1960s,

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu successions. the crystallinebasementandpre-Alpinesedimentary Alpine agebelieved tohave affected various partsof of thisareawiththetranspressive tectonicsofthe by Pasci (1997), who relatesthegeologicalevolution interpreted inthepast,hasrecentlybeenre-examined The structuralsettingoftheSupramonte,variously zone. as belongingtothegreenschistfacies ofthebiotite schist-like sedimentspetrographicallydetermined of theSupramonte.Itiscomposedpolydeformed only cropoutextensively inthesouthernmostportion terrains ofthePalaeozoic crystallinebasementthat and angulardiscordanceontheschistand/orgranite This sedimentarysuccessionrestswithstratigraphic Tuttavista). the GulfofOroseicoast, andMonte Central-Eastern Sardinia(thecarbonatemassifalong sedimentary successionthatcropoutinmostof limestone rocks,oftheJurassic-Cretaceous the Supramonteiscomposedprimarilyofdolomitic From ageologicalandhydrogeologicalstandpoint, slopes oftheSupramonte. Gorropu springthatgushesfromthecentral-eastern in theOlienaandDorgali countryside,aswellthe situated alongtherightbankofRiver Cedrino Gologone, SanPantaleo andSu Tippari springs, It extends over about170km the largest karstifi The “--” Supramonteisoneof Geological maps Dorgali. 25: 547sect.ICantonieraGennaSilana,500II Stop 3.1 Topographic maps Recommended maps Rio Flumineddu. gorge cutinthelimestonerocksbywaters ofthe Supramonte andtotheGorroppucanyon aspectacular There arewonderful excursions intotheDorgali be easilyfollowed onfootorinanoff-road vehicle. route continuesalonganunmade-uproad,whichcan Having reachedthe GennaSilanapass(1008m)the The mainrouteproceedsalongthepaved road. General information ontheitinerary (37 km). From CalaGononetotheGennaSilanaPass ed massifsinSardinia. –Sheet1:100,000:208Dorgali. –IGM1:25,000tables,series DAY 3 2 andsuppliestheSu & Vernier (1993),identifi From astrictlyhydrogeologicalpointofview, Sanna of theSupramonte the hydrostructural andhydrogeological setting General information concerning (2002). using thegraphicschemespublishedbySannaetal. but theinformationgatheredtodateissummarized insight intothehydrogeologyofSupramonte, No new dataareprovided hereforgainingadeeper from thesmallerSuGologonespring. presently securedbypartiallycapturinggroundwater increase drinkingwater suppliesinthearea,whichare and quantifi groundwater resources. A betterunderstanding that maypotentiallycontainmajorandstrategic northern partoftheSupramontehostsanaquifer The fi groundwater circulation. fractured andkarstifi proposed byCivita etal.(1992)formoreorless to bedetermined,usingthebasicconceptualmodel enabled theSupramontegroundwater fl Research conductedbytheabove authorshave understanding ofthehydrogeologyarea. provided animportantcontribution togainingabetter and theGruppoSpeleologicoFaentino whichhave Spano Cagliari,UnioneSpeleologicaBolognese Club Oliena,GruppoSpeleo Archeologico Giovanni Urzulei, GruppoRicerche Ambientali Dorgali, Speleo Grotte Cagliari,Gruppo Archeo Speleo Ambientale Nuorese, CentroSpeleologicoCagliaritano,Gruppo Federazione SpeleologicaSarda,GruppoGrotte various groupsofspeleologists. These includeLa exploration andgroundwater tracingconductedby and onthebasisoffi Vernier 1993;Sanna(1996)andetal.(2002), by monitoringspringsandfi determined, throughdetailedstudiesofthearea,and hydrogeological settingoftheSupramontehasbeen On theotherhand,overall hydrostructuraland Omene, fi Flumineddu valley, situated tothenorthofMonte 16, sections A, BandC),betweenOlienatheRio overlying carbonaterocksinthefi The contactbetweenthecrystallinebasementand contact surface betweenthetwo formations. and onthehorizontalvertical orientationofthe carbonate cover, theunderlying Palaeozoic basement the basisofbeddingrelationshipsbetween Supramonte (Figure16). These wereidentifi ndings oftheirwork alsosuggestthatthecentral- rst occursatanaltituderangingfrom800 cation ofthisresourcewould enableto ed carbonateaquiferstointerpret ed fi ed ndings fromkarstcavity eld surveys, bySanna& ve mainsectorsinthe rst sector(Figure o pattern ow 26-05-2004, 11:07:43 e on ed HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37 Volume n° 5 - from P37 to P54 n° 5 - from Volume

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu permeability thresholdthatwas producedwhenthe 17) maylikely beattributed totheexistence ofa Vernier (1993)theemergence ofgroundwater (Figure of thepermeabilitythreshold. According toSanna& be classifi From ahydrostructuralstandpoint,thespringscan regional authorities asanaturalmonument. are setSuGologonehasbeenoffi Because ofthestunninglandscapeinwhichsprings Manna” and“Sa Vena Minore”. groundwater emerges astwo springscalled“Sa Vena At SuGologone(elevation about103ma.s.l.) emerge. the valley, theSu Tippari andSanPantaleo springs Sanna etal.(2002),comesoutand,furtherdown hydrogeological signifi water notmarked onoffi where theSuGologonespring,asmallpoolof along thenorthernedgeoflimestoneformation The Supramonte’s mainkarstfeatureshave formed the northern Supramonte Springs andhydrogeological settingof granite formationsofPalaeozoic age. being totallyconfi On thewhole,itexhibits S-Nverging, theaquifer Cretaceous bedsoccurtowards thecore. folds aretheGorropuandLanaittosynclineswhere of theMesozoicsediments. The mostconspicuous (Pasci, 1997),like theonesatLanaitto,andfolding deformation, notablymajortranspressive faults The limestonesequenceshows clearsignsof by Quaternarydetritussediments. an elevation ofatleast800ma.s.l.,isoftenobscured Mesozoic sedimentarycover. The boundary, lyingat respectively, thePalaeozoic bedrockisoverlain bythe 16, sections A andF),thefourthfi the westernfringeofcarbonatemassif(Figure Along thesouthernedge(UrzuleiSupramonte)and m a.s.l.nearthepass. westwards, risinggraduallyfrom350ma.s.l.to1000 Silana pass,thebasement–cover contactisdirected E), betweentheGorropucanyon andtheGenna In thethirdsector(Figure16,sectionsDand spring. at between100and350ma.s.l.neartheGorropu of theSupramonte,istectonicinnatureandlies (Figure 16,sectionsCandD),ontheeasternedge The basement–cover contactinthesecondsector springs. the areabetweenSuGologoneandSanPantaleo to 900ma.s.l.,descendingaround100a.s.l.in ed ashaving emerged duetojuxtaposition ned bytheimpermeableschist- cance was recognizedby cial mapsbut whose cially recognizedby fh sectors fth rapidly andresumedinitialvalues relatively quickly infi rainfall hadceased,andintheabsenceoffurther of precipitation,Sannaetal.(2002).Similarly, once interval forwater level measurement)fromtheonset with lagtimesrangingfromafew to24hours(time observed even afternotparticularlyheavy rainfall, In fact, sharpincreasesinspringfl monitored springtobehave ratherimpetuously. rainfall regime intheSupramonteshowed fl Comparison offl during dryperiodstoafl main spring,whichwas foundtorangefrom60l/s been possibletoreconstructspringfl the SuGologonesprings.Basedonresultsithas resources intheSupramonte,includedmonitoringof A comprehensive studyconductedforassessingwater 100 l/s. captured, average withdrawals amountingtosome the mainkarstnetwork. Part ofthespringwater is from afractureintherockwhichisconnectedto Groundwater fromtheSa Vena Minorespringgushes large siphon. of around107mandisvery likely theupperendofa a karstconduitthathasbeenexplored down toadepth typical vauclusian springasthegroundwater risesup The Sa Vena Mannaspringcan alsobedescribedasa Su GologoneandtheSanPantaleo springs. in theentiresectorbetweenareaupgradientfrom carbonate cover was upturnedandpartiallyoverturned contact betweenthecrystallinebedrockandMesozoic Figure 17-Schematic geologiccross-sectionofmain“Su Gologone” spring:1)granite;2)schist; 3)basalJurassic alluvia; 6)Plio-Pleistocenefluvial-lacustrinedeposits;7) ltration episodes,fl dolostone; 4)Jurassic limestone;5)ancientterraced Recent andpresentalluvialsediments. uctuations inwater level with ow ratewas foundtodecrease ood fl ow rateof8000l/s. ow werealways ow fromthe ow inthe 26-05-2004, 11:07:47 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

except for major recharge events when lag times of as entrances. The opening to the semi-active cave (Sa much as 30 days were recorded. Oche) lies at an elevation of around 150 m a.s.l., Unfortunately, access to the other springs in the that of the inactive portion (Su Bentu) at about 200 Supramonte, situated further downvalley, is impeded m a.s.l. for most of the year as they are submerged beneath the The entrance to the Sa Oche cave leads into a wide Cedrino reservoir. passage that ends abruptly after just 200 m, at an For this reason it proved impossible to monitor fl ow elevation of 135 m a.s.l., in a sump which is connected rates, as had been done for Su Gologone. to the semi-active passages of the Su Bentu cave. However, the scant data reported in the literature The Su Bentu cave consists of a vast system of indicate the San Pantaleo springs to be situated at an water carved passages extending over a total length elevation of around 95 m a.s.l. and to have fl ow rates of more than 14 km. In several places the passages comparable with the Su Gologone springs. On the reach the saturated zone, situated at an elevation of other hand the Su Tippari spring lies at an elevation of approximately 105 m a.s.l., thus very close to the around 100 m a.s.l. with an estimated minimum fl ow main groundwater emergence at Su Gologone. rate of roughly 25 l/s. The S’Istampu-Sas Ballas cave, whose entrance lies Two large karst cavities have been identifi ed along the at 143 m a.s.l., extends for about 2 km and at 117 m northern edge of the carbonate massif. The fi rst, the a.s.l., a short distance from the rear end of the cave, Guano cave, is situated between the Su Tippari and reaches a siphon. San Pantaleo springs, the second the Mussintommasu Several areas of both the Sas Ballas and Su Bentu–Sa cave (also known as Peppino Ladu cave) lies a little Oche caves are partly fl ooded even at elevations way further uphill from Su Gologone. beyond the saturated zone. A number of underground Both these caves only become fl ooded after major lakes have formed in these areas that based on infi ltration events when they act as overfl ow springs. information collected to date can be interpreted as The Guano cave, which has three entrances at “perched” zones of the karst system. elevations of between 95 and 120 m a.s.l., consists of a spacious tunnel, reaching a maximum elevation Hydrogeological features of the of 107 m a.s.l. The cave extends for approximately southern Supramonte 2 km underground and has two sumps located at an The southern portion of the Supramonte forms the elevation very close to the Su Gologone springs. main source of groundwater supply to the karst The entrance to the Mussintommasu cave lies at system drained by the Su Gologone springs. an elevation of about 118 m a.s.l. in a rocky wall Here, several swallow holes or stretches with losses above Su Gologone and extends over no more than beneath the streambed have formed close to the 50 m. This karst cavity is of major hydrogeological bedrock-carbonate cover contact. There are also a interest because at 103 m a.s.l., which coincides with few caves that function as water collectors conveying the outlet elevation of the Su Gologone springs, it groundwater towards the deeper parts of the karst is permanently fi lled with water. Pot-holers and aquifer. underwater exploration have reached a depth of The Badu Osti swallow hole, situated at an elevation roughly 80 m from the surface. of 892 m a.s.l. and the most important groundwater To the South of the springs, proceeding into the heart loss point receives discharge from the upper Rio of the Supramonte, are another two large cavities: Flumineddu. the Su Bentu-Sa Oche complex and S’Istampu Sas The most interesting karst cavity in hydrogeological Ballas. terms is the Edera system, the entrance to which lies These caves form part of a single karst system of at approximately 950 m a.s.l.

which to date 16 km have been explored. The system Inside this cave is a main collector structure that P37 to P54 n° 5 - from Volume consists of spacious cave passages that were later hosts a subterranean torrent with variable fl ow rate. deepened by running water. The caves become partly After following a relatively winding path through the fl ooded after heavy rainfall. After exceptional rainfall passage, the water of this torrent is dispersed in an events the Sa Oche and Sas Ballas, and similarly area of the cave that as yet remains unexplored. the Guano and Mussintommasu cave mouths, act as Two water tracing tests have been carried out at the overfl ow springs yielding fl ow rates of up to several Badu Osti swallow hole and the Edera cave. The fi rst, cubic metres a second. conducted in August 1969 by the Gruppo Speleologico The Su Bentu-Sa Oche complex has two separate Faentino, the Unione Speleologica Bolognese and the

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu carbonate massifformsasinglehydrologicalsystem. Edera cave, have unequivocally confi 1999 bytheFederazioneSpeleologicaSardain and inparticularthewater tracingtestsperformedin The resultsofresearchcarriedoutintheSupramonte How thekarstsystemworks 1000 l/stonomorethan10indryperiod. regime, discharge fl is characterizedbyavery variable hydrodynamic between thebasementandcarbonateaquifer This springemerges close tothestratigraphiccontact 350 ma.s.l.,liestheGorropuspring. further downslope, atanelevation ofapproximately Lastly, SEoftheOrbisi-Donini cave, andmuch the underground karstnetwork. sinkholes beneaththeRioFluminedduandreturnedto The surface water isthencapturedbyaseriesofsmall below. above ground,eventually joiningtheRioFlumineddu in theOrbisiswallow-hole, continuingitsjourney further downvalley, gushesthegroundwater captured Donini cave. Fromthecave openinginavertical wall 790 ma.s.l. This swallow-hole isconnectedtothe Orbisi swallow-hole atanelevation ofapproximately along theCodulaSaMela,eventually endingupinthe Edera system,whiletheexcess fl discharged from thiszoneispartlyabsorbedbythe southern Supramonte.Duringfl catchment basininthePalaeozoic bedrockofthe part ofthesurface runoff collectedinthegroundwater Following heavy rainfall, thiskarstcavity receives cave. systems, themostimportantbeingOrbisi–Donini Supramonte alsohostsanumberofsecondarysub- The mainkarsthydrologicalsystemintheUrzulei al. (2002). Su Gologoneand Tippari springs,BandieraF. et with satisfactory results,recorded76dayslateratthe 10 KgofNa-fl has beenpossible. swallow hole,i.e.wherenospeleologicalexploration torrent joinsthewater fl the Ederacave downstream fromthepointwhere in June1999. The water tracerwas introducedinto Speleologica Sarda(SardinianSpeleologicalSociety) The secondtestwas carriedoutbytheFederazione (Assorgia etal.,1968). situated atanelevation ofapproximately738ma.s.l. into themaincollectorinEderacave atapoint waters capturedbytheswallow holeatBaduOstifl Centro SpeleologicoCagliaritano,indicatedthatthe uorescein tracerwas usedforthistest, ow ratesrangingfrommorethan owing infromtheBaduOsti od fl ood ow isconveyed rmed thatthe ow thewater ow ow Large amounts ofinfi groundwater resurgence. is accompaniedbyincreasedfl episodes, increasesthepressureinconduitswhich in thesystem,like thosecausedbymajorinfi level oftheSuGologonespring. Any perturbations high pressurekarstconduitssituatedbeneaththe indicate theexistence ofadrowned aquifer, with which almostalways coincidewithrainfall events, Clearly theabruptincreasesinwater level observed, the larger spring. observed bySannaetal.(2002)duringmonitoringof justifi to thesouthofareawherespringsemerge, The existence ofasaturatedzoneinthekarstsystem (Su GologoneandSanPantaleo). local baselevel ofbetween103ma.s.l.and95 can reasonablypresumedtobesituatedbelow the the massifwherebedrock-carbonatecover contact Pantaleo), theLanaittovalley andthecentralpartof the springsemerge (SuGologone,Su Tippari, San between thenorthernpartofSupramontewhere On thesurface thiszonecoincideswiththearea in thecentral-northernpartofSupramonte. relatively extensive saturatedzoneinthekarstnetwork and hydrostructuralsurveys indicatethepresenceofa Gologone springstogetherwiththehydrogeological Speleological observations, monitoringoftheSu northernmost partoftheSupramonte. fl and waterpools alsoexist fromwherethegroundwater runoff infi several pointsinthispartofthemassifwheresurface supplies thekarstnetwork. Infact, notonlyarethere It isthesouthernsectorofSupramontethat (Guano, Mussintommasu,SuBentu-SaOcheandSas terms allthecaves existing inthenorthernpartof The above fi the SaOcheeSasBallascave entrances. increase inwater levels makes thespringsgushfrom caves, whileittakes afew daysbeforethegradual have beenrecordedfortheGuano e Mussintommasu springs inarelatively shorttime.Longerlagtimes fl hydrogeological observations have shown that It isworth mentioningthatspeleologicaland Pantaleo springs. base level oftheSuGologone, Tippari eSan increasingly higherelevations comparedtothelocal increase water levels andfl the aquiferhasalreadybeenpartiallyrecharged, can that occursinlimitingconditions,whenforexample ows rapidlytowards thespringssituatedin oodwaters inthekarstsystemreachSuGologone es therapidresponse oftheSuGologonesprings ltrates throughthesurface, but several caves ndings indicate thatinhydrogeological ltrating water orinfi ood thecaves situatedat ow rateatthe pointof 26-05-2004, 11:07:51 ltration ltration HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37 Volume n° 5 - from P37 to P54 n° 5 - from Volume

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu stopping attheGennaSilanapass. 125 mainroad,pastthetunnelforCalaGononeand Dorgali countryside,proceedingsouthalongtheSS One very interesting excursion istotheheartof presumed water level ofthebasalsaturatedkarst. the karstsystemsandperennialsprings,to pattern describedabove inrelationtotheelevation of Supramonte. Itillustratesthegroundwater circulation Figure 18shows alongitudinalsectionofthe massif. of infl springs areunabletocopewiththehugequantities when theSuGologone, Tippari andSanPantaleo zones ariseandwithinwhichgroundwater onlyfl and becauseanupperfringeoccurswhereperched beneath whichthecavities areperenniallyfl signifi demonstrated, thewater levels inthesystemvary In thiscase,asspeleologicalobservations have groundwater reserves. conduits andfracturesthathostmajor zone withanetwork ofvariously connected part oftheSupramonteexists asaturated On theotherhand,incentral-northern infi depending ontheamountofwater scant andthefl topography, the system’s reserves are governed toalarge extent bybedrock In thiscasegroundwater circulationis inside theEderacave. quantities ofinfl karst conduitsrapidlydrainingeven large exists, numerouscollectorswithinlarge strong hierarchyofthedrainagenetwork In thesouthernpartofSupramontea network (central-northernSupramonte). well asan“interdependentlydraining” (Urzulei Supramonte–Ederasystem),as primary dominantgroundwater network and cavities ofthe Supramontethereisa In thissense,inthesubterraneanpassages al. (1992). modelling techniqueproposedbyCivita et Supramonte usingthebasicconceptual karst network ofthe al. (2002)have schematicallydescribedthe relation tootheraquifersinItaly, Sannaet To bettercharacterizethekarstaquiferin Ballas) actasoverfl ltrating intothegroundwater network. cantly. This isbothbecausealevel exists owing water infi ow ratesvary signifi owing water, ashappens ow springs. ltrating throughthecarbonate cantly

ooded, ows can attempttoclimbupthesheerwalls, whichata dizzyingly highwalls. Onlyexperienced mountaineers rock masses.Birdsofprey nestinthecrevices ofits in theterritoryofUrzulei,areenormousrounded Scattered abouttheGorroppugorge, whichissituated of thecanyon (Figure 19). Visitors have plentyoftimetovisitaninterestingpart are morethan400metreshigh. approximately amillionyearsold.Itsvertical walls The Gorroppucanyon isaspectacularkarstgorge structure fl where surface runoff infi entrance totheEderacave andanumberofpoints carbonate cover isclearlyvisibleas well asthe between thecrystallinebedrockandMesozoic geomorphological featuresofthearea. The contact carbonate massif,theGorropuspringandmain This routetakes intheentireeasternedgeof owing intothekarstnetwork. ltrates throughthecarbonate Figure 19-SuGorroppu. 26-05-2004, 11:08:01 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

certain point are interrupted by perennial lakes. Stop 3.2: From the Genna Silana Pass to Su Gologone (60 km). General information on the itinerary The route follows the paved road to the famous Su Gologone restaurant. The short path leads us alongside the rocky wall, amidst eucalyptus woods near the River Cedrino and thick Mediterranean bush.

Recommended maps Topographic maps –IGM Tables 1:25,000, series 25: 500 sect. II Dorgali, III Oliena. Geological maps – Sheet 1:100,000: 208 Dorgali.

On reaching the Su Gologone spring- Mussintommasu cave (Figure 20), you will also be able to see the sub- vertical contact between the basement and carbonate cover which is partly overturned.

The karst Su Gologone spring is an important and fascinating spring. All year round its waters feed the Cedrino reservoir which supplies water to towns and villages in the area. Its fascination lies in its undiscovered mysteries. Several attempts have been made to explore the innermost core of these springs. The current record is held by the Frenchman Olivier Figure 20 - Su Gologone spring. Isler, one of the famous cave-divers sponsored by lateral transcurrent faults and the boundary between “Sector”, who succeeded in descending to 108 metres, the carbonate structure and the Palaeozoic bedrock. but without reaching the bottom. Lanaitto Valley is the paleovalley of the River Flumineddu. Following landslides and earthquakes Stop 3.3: in ancient times today the river fl ows much further From Su Gologone to the Lanaitto Valley (10 km). eastwards in the Dorgali territory. General information on the itinerary The river fl owing through the Lanaittu valley, called To reach the valley (Figure 21), turn right before the Rio Sa Oche, is one of the numerous torrents that the large square where the springs are situated. The over the millennia have carved out the extraordinary road, marked with a sign, is cemented for the fi rst karst landscape of the Supramonte, including the few kilometres but then turns into a dirt road. Follow famous Sa Oche, Su Bentu and Eliches Artos caves. this track, preferably by jeep for about 8 km until you Alongside these surface erosion processes have come to a cross-roads. To the right, the Sa Sedda e Sos created an endless series of narrow gorges, crevices, Carros nuragic village, to the left the Nuragic village dolines, gaping sinkholes and rock crags creating a of Tiscali. Turn left and continue for a few kilometres striking and distinctive landscape.

until you come to the valley. P37 to P54 n° 5 - from Volume Lanaitto Valley is one of the areas in the Supramonte Recommended maps with the largest number of cavities, chasms and caves Topographic maps – IGM Tables 1:25,000, series carved into the limestone ridges of this heterogeneous 25: 500 sect. III Oliena. and tormented complex. They bear witness to Geological maps – Sheet 1:100,000: 208 Dorgali. the eroding force of impetuous rivers long since disappeared that in ancient times shaped the entire Once you have reached Lanaitto Valley you will be region. These include the Corbeddu cave, named able to admire the synclinal structure bounded by two after a famous bandit who took shelter there in times

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu Topographic maps Recommended maps (the voice) andSuBentu(thewind)caves. site, thecomplex groundwater systemoftheSaOche you reach,atashortdistancefromthearchaeological Proceed inthesamedirectionasprevious stopuntil General information ontheitinerary caves. From Lanaitto valley totheSuBentuandSaOche Stop 3.4: extinct about4,000yearsagoforreasonsunknown. the Prolagussardous,anancientrodentthatbecame Grotte diNuoro,ofthefi expedition of American scientistsandtheGruppo the cave becamefamous afterthediscovery, by an (Bathysciola majori,Patriziocampa sardoa).However, discovered andtherarespeciesof insectsidentifi paleontological interestforthelarge hoardoffi gone by. This cave isofsignifi Figure 21-Lanaittovalley. longest (over 20km)andmostinterestingcaves in The “SaOche-SuBentu”systemisoneofthe e SanPantaleo. points ofthemainspringsatSuGologone, Tippari relationships betweentheelevations ofthedischarge Take alookatthecave entrancesandexamine the Geological maps 25: 500sect.IIIOliena. –Sheet1:100,000:208Dorgali. –IGM Tables 1:25,000,series rst completeskeleton of cant archaeologicaland nds ed oak andjunipertrees.Oncewehave climbed upthe in placeswiththickvegetation andenormousholm appear intherocky mountain sides,whicharecovered carved bywind/water erosion,fi little furtherupthemountainside.Several hollows, few millionyearsagoproduced thelarge dolinea likely createdbythesamegeologicalprocessthata Tiscali, acrevice inthemountainsidethatwas most territories. The routecrossestheso-calledCurtigiadi together withtheLainattovalley, betweenthetwo the craggyMonte Tiscali, whichmarkstheboundary, Supramonte liesthe Tiscali doline,onthecrestof On thesouth-easternedgeofDorgali-Oliena Geological maps 25: 500sect.IIIOliena. Topographic maps Recommended maps trek tothevillage,sometimesacrossdiffi mountainside totheNorth.Itisaone-and-a-half-hour through acrevice thatsplitsthehuge,magnifi The routetothe Tiscali Nuragicvillagetakes us General information ontheitinerary Tiscali. From theSu Bentu andSaOchecaves toMonte Stop 3.5: course requiressomedegree ofexperience. whole cave systemtakes atleast20hoursandof –Sheet1:100,000:208Dorgali. –IGM Tables 1:25,000,series pools. To visitthe visited thefi once they have visitors turnback waters. Usually and crystalclear breathtaking beauty stunned bytheir effort andwillbe was wellworth the they willfi the fi eventually leadto and descentsthat by slightascents of roomsseparated with itssuccession rather challenging well fi Newcomers might the Supramonte. ssures andgulleys rst pools.But nd theroute cult terrain. 26-05-2004, 11:08:06 n it nd cent rst HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

has two entrances. One is very high up, and can only be reached via an 80 m descent by rope. The second entrance leads into a widened passage that after a few metres opens up into the main room, the sheer size of which leaves visitors in awe. High above is the upper cave entrance through which, at around midday, a ray of sunlight penetrates, illuminating the whole chamber with its huge and fabulous concretions.

DAY 4 Stop 4.1: From Su Gologone to (20 km). Figure 22 - Nuragic hut. General information on the itinerary steep stony scree, and through the crevice, the route The route proceeds along the paved road. proceeds for a long stretch along the inside of a niche, a bright reddish wall looming tall above. Finally we Recommended maps reach the single entrance to the doline, a gigantic Topographic maps – IGM Tables 1:25,000, series limestone cavity created by tectonic movements. 25: 500 sect. IV Nuoro Est, 499 sect. I Nuoro Ovest. Scattered over the bottom of the cavity are the remains Geological maps – Sheet 1:100,000: 208 Dorgali, of what was once a large Nuragic village, dating to the 207 Nuoro. latter part of the Nuragic age. The forty or so largely round, but some rectangular, Nuoro is a lively city (Figure 23), whose economy is huts, (Figure 22), are divided into two districts and based on the services sector and commerce. back onto the doline walls. Though not much remains The town rises on the edge of a plateau in the heart of the huts the foundations are still visible. The origins of the Barbagia region, and commands a stunning of this village remain a mystery. In fact the building panorama of the surrounding mountains. technique differs from the traditional method used in The city was originally divided into two districts, the other Nuragic villages. However, it following the typical lay out of the mountain villages is believed to date to the late Nuragic age and may coincide with the Roman conquest of the island.

Discovered in the late 1800s during wood clearing in the area, the village was more or less intact and consisted of two groups of truncated cone and rectangular huts built of mud and stone with juniper lintels. Here perhaps the civilization resisted Roman invasion for centuries. Little now remains of this archaeological site,

sacked by tomb robbers and trampled P37 to P54 n° 5 - from Volume by visitors from the 1930s onwards. The atmosphere, the colours of the limestone and the centuries-old holm oaks make this site a unique and unforgettable place. Apart from the Nuragic village, a large and beautiful cave also cuts into the heart of Monte Tiscali. The cave Figure 23 - Map of the historic centre of Nuoro.

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu 17 of GracesChurchissituatedandfromwheretheold The two roadsmeetinthesquarewhereOurLady central axis,bustling withlifeandpacked withshops. these two mainroadswhichcontinuetobethecity’s The newer partsofthecityhave beenbuilt along Via LamarmoraandCorsoGaribaldi. shepherds lived), joinedbythemainroad,today the SantuPedrudistrictinupperpart(where lower partofthetown (wherethefarmers lived) and in theBarbagiaregion. The Seunadistrictinthe Leading off thissquareis Viale Manzoni.Proceeding reached. Traditions. Figure 24-MuseumofSardinianCostumesandFolk Figure 25–GraziaDeledda’s house-museum. th centurychurchofthesamenamecanbeeasily (Figure 25). Nuoro whowon theNobelprizeforLiteraturein1926 Deledda’s HouseMuseum,thefamous writerbornin are thesmall17 resurfaced usingtheoriginalpebbles. Worth visiting winding passageways someofwhichhave been the characteristicSanPietrodistrict,withitsnarrow Lastly, goingbacktopiazzaS. Giovanni, wecometo (Figure 24). antique objectsassociatedwithSardiniantraditions collections ofcostumes,jewellery, furniture,rugsand Costumes andFolk Traditions withitsprecious by proceedingalong Viale Ciusapastthecharming , agranitetectonicblockthatcanbereached the cityitself.NottobemissedavisitMonte Interesting excursions can bemadenotfar from Geological maps 25: 500sect.IVNuoroEst. Topographic maps Recommended maps The routeproceedsalongtheasphaltedroad. General information ontheitinerary From Nuoro toMonteOrtobene(8km). Stop 4.2: buried. The roadclimbsuphillpastsomecoolsprings Church oftheSolitude,whereGraziaDeleddais th the city, istheMuseumofSardinian position withastunningview of the hill,inawonderful panoramic the Sant’Onofriohill:attopof Bearing rightweeventually reach of theSnow Cathedral. Neoclassical facade oftheOurLady which isdominatedbythemajestic Piazza ofS.MariadellaNeve, further uphillwecometotheairy Sardinian Handicraftsontheright, with thepermanentexhibition of gardens toPiazza Vittorio Emanuele, XXIII, andonpastthepublic Proceeding along Via Giovanni from theNuoroprovince. fi Roman, Nuragicandpaleontologic houses anumberofinteresting Archaeological Museumwhich Leonardo da Vinci wecometothe along thisroadandthen Via CenturyS.CarlochurchandGrazia –Sheet1:100,000:207Nuoro. nds fromtheBarbagiaregion and –IGM Tables 1:25,000,series 26-05-2004, 11:08:12 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

eventually reaching the thick holm oak forest that the volume of fractures and on the disintegration and covers the northern mountainside. alteration of the rock. The Ortobene mountain consists of normal granite, Groundwater composition at Monte Ortobene is quartz, orthoclase, oligoclase, biotite, and muscovite strongly affected by wind-borne salts from the sea, being the main components. The medium to coarse like elsewhere in Sardinia. In fact the Na+/Ca2+ ratios grained granite is locally porphyritic. may represent the sodium to calcium ratio in the In the early 1970’s, the small catchment of Sedda plagioclase of the rock, which should be an oligoclase 2 ‘e Ortai (0.414 km ), on the southern side of the (Ab80An20). mountain, was chosen as a pilot basin for a systematic At Nuoro the wind-borne sea salts account for almost campaign of hydrogeological investigations in the half, the other half coming from rock weathering. In granite areas of the island (Barrocu & Larsson, 1977). similar pilot areas on the coast sea salt accounts for The bottom of the catchment is cut by a small NW- around 75%. SE fl owing river and bordered by a steep horse-shoe rocky barrier. Stop 4.3: The granite is locally intersected by a lamprophyric, From Monte Ortobene to Arborea (106 Km). SW-NE trending, subvertical dike at least 4-5 m thick, General information on the itinerary which crops out along the road and has been identifi ed The route proceeds along the asphalted road. magnetic surveying. The bottom of the basin is covered with a weathered Recommended maps granite overburden, increasing in thickness towards Topographic maps – IGM Tables 1:25,000, series the outlet, where the bedrock suddenly outcrops. 25: 538 sect. I Terralba. Monte Ortobene is a tectonic block, uplifted between Geological maps – Sheet 1:100,000: 217 Oristano. the grabens of Rio Marreri - Isalle, to the north-west, and Oliena, to the south. The block is split into Just 70 years ago Arborea was a vast expanse of several minor blocks with varying degrees of vertical uninhabited and unhealthy wetlands. It was dotted displacement. The block is mainly affected by shear with rivers, water courses, and more than 50 lagoons stresses, due to post-crystalline shear deformation, and marshes, where malaria thrived. The whole tension fractures being less relevant. The major shear area was infested with insects, snakes, tarantula and families strike N20°W-S20°E and N60°W-S60°E, and scorpions and its nickname “Ala Birdis” (the devil’s are sub-vertical. NE-SW verging overthrusts have wings) was no exaggeration. NW or SE dip ranging from 0-40°. Land reclamation work got under way in 1919 in the The maximum elevation of the basin is 920 m a.s.l. area between the S’Ena Arrubia lagoon to the North Annual total rainfall of 650.2 mm was recorded in a the Sassu lagoon to the East and the San Giovanni rain gauge situated at 715 m a.s.l. lagoon to the South and was completed in 1928. In From the hydrogeological point of view, and based 1937, when the large Sassu salt marsh was dried on the results of geophysical surveying carried out out another 3000 hectares of land was reclaimed for with refraction seismic, geoelectric, electromagnetic agriculture use and animal raising. and magnetic methods, and of drilling campaigns, The reclamation was hailed as a major engineering the basin is believed to be divided by the two agronomic feat, and also as a miracle. The complex almost-equally-spaced shear fracture systems, into irrigation system designed (irrigation channels a mosaic with interconnected secondary fracture and water scoop) knew no precedent elsewhere in systems. Natural groundwater reservoirs depend on Italy. Likewise the modern electro-hydraulic pumps the rotational effects of the separated small blocks, installed in the water scoop on the Sassu salt marsh,

due to shear movements. Drillings operations were in itself an extraordinary architectural monument, had P37 to P54 n° 5 - from Volume concentrated in a 15 m wide low velocity zone of never been used in similar circumstances. 2800 m/s, considered to be the most promising. A major effort was required to combat the insects, Based on the results of pumping tests in the wells, a especially the mosquitoes, using both chemical and storativity of 0.05% was calculated, corresponding biological means. Artifi cial bat roosts were placed to an estimated bed storativity of about 4÷7,000 at different points in the reclamation area and the m3/km2. bats multiplied rapidly contributing signifi cantly to The storage capacity of fractured rocks depends on defeating the malaria carrying mosquitoes.

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu some 115km in Sardinia. The territoryextends over anareaof boast thehighestagriculturalandanimalproductivity Today, themodernfarming centreof Arborea can was changedto Arborea. end oftheSecond World War, thenameofvillage Mussolinia was founded,andto3800in1936. At the increasing to2253in1930,whenthemunicipalityof At thetime Arborea countedathousandinhabitants, reclaimed land(Figure26). “Mussolini’s village”was built in thecentreof In 1928duringfascist times,thefi were grown, andcontinuetobesotoday. horticultural crops,water melonsandstrawberries connected byadenseroadnetwork andcereal, to Sardinianfarmers. Large farms began operating peasants fromtheNorthofItalyandaminorpart The newly createdfarmland was handedover to Figure 26-Theoldtown of Arborea. Figure 27-S’Ena Arrubia lagoon. cultivated fi Today theorderlylandscapeisasuccessionof inhabitants. elds divided byrows ofpoplarsand 2 withapopulationofaround3990 rst villagecalled a drainagebasinof3.376km Tirso river, themost importantriver inSardiniawith (Figure 28). The plainiscrossedbythe150kmlong Santu Lussurgiu andtotheSouthbyRioMogoro area isboundedtotheNorthbyRioMannuat Arci mountainrange(812m)totheEast. The study that extends fromtheseato West uptotheMonte of theCampidanoalluvialplainandoccupiesabelt The Oristanoplainincentral-westernSardiniaispart 27). are alsohometonumerousotherbirdspecies(Figure their journey between Africa andFrance. The lagoons the pinkfl Arborea. These areofsignifi Worthy ofmentionarethelagoonssurrounding furious mistralwind. sandy soilsinplaceandtoshelterthecropsfrom The numerouspinewoods intheareaserve toholdthe water allover theterritory. strategically situatedwater pumpsdistribute irrigation essential forsustainingagricultureandtheenormous, The numerouscanalsthatcrossthe Arborea plainare eucalyptus treesandofmodernstables. Giusta, S’Ena Arrubia andSanGiovanni. The area most importantonesbeingCabras,Mistras,Santa Oristano orintothenumerouscoastallagoons, All therivers intheplainfl amingos make thisanannualstopover on Figure 28-TheOristanoplain. ow outintotheGulfof cant naturalvalue and 2 (Fadda &Pala, 1992). 26-05-2004, 11:08:17 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

Figure 29 - Geological map of the Oristano plain. Holocene: 1. Present and recent beach sands passing to coastal dunes; 2. Pebbly-sandy or clayey alluvia and clayey silt palustrine or brackish deposits. Pleistocene: 3. More or less cemented dune sands; 4. Pebbly-sandy alluvia covered primarily with (ancient) relict dunes; 5.Pebbly terraced alluvial deposits with interbedded sand,; 6 Pebbly alluvial deposits of the upper terraces.

still presents several depressions, former marshland, that today have been largely reclaimed.

Geomorphology Figure 30 – Stratigraphy in the Arborea area. 1:Fine The Oristano plain formed on the Campidano Graben. yellowish sands interbedded with clay hosting phreatic It has a practically level surface and lies at an average aquifer; 2: blackish clay; 3:sandy clay hosting aquifer elevation of about 10 m a.s.l. Despite the monotonous of moderate yield; 4: blackish silty clay; 5: black clay; 6: landscape the plain exhibits relatively complex blackish clay containing shell; 7: pebbly clay; 8: pebbly layer with sand with aquifer under pressure; 9: marly characteristics. The northern portion is characterized clay; 10: sandy clay; 11: grey clay; 12: grey marly clay; P37 to P54 n° 5 - from Volume by two alluvial deposits, one overlying the other, 13: gravelly layer with aquifer under pressure. while the southern part is occupied by recent alluvium of the Rio Mogoro. The depressed parts were constantly prone to fl ooding before the river banks 1995). Eolian sands have also deposited creating a were raised (Fadda, 1990). coastal dune system that locally reaches a height of The last sedimentation phase produced a succession 8m. In the Arborea and Santa Giusta areas lies the of gravel, sand, silt and clay deposits (Barrocu et al., largest expanse of sand dunes in Sardinia. Figure 29

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu sand/gravel andclay. The surfi of varying thickness,composedofasuccession overlies aseriesofconfi bed liesatadepthofbetween8and11m, and gravel hasbeenidentifi A phreaticorsemi-confi Hydrogeology shows thegeologicalmapofstudyarea. aquifer (afterSalis&Soddu,2003). Figure 31-Isosalinitycurves (µS/cm)for thesurface along theRioMogoro,mostofwellsdriedup. At For example afterconcreteembankmentswerebuilt aquifers hasdiminisheddrastically. the smallerrivers. As aresult,river runoff intothe concrete embankmentshave beenbuilt onmostof The river Tirso hasbeendammedupstreamand depth ofmorethan500m. suggested thatthemulti-layeraquiferissituatedat A numberofexploration boreholesdrilledinthearea core drillednearthetown of Arborea. construction. Figure30shows thestratigraphyofa effects ofshort-circuitingasaresultshoddywell the aquifershave becomeinterconnectedduetothe of variable thickness.However, inseveral points multi-layer aquiferareseparatedbyalayerofclay ned orsemi-confi ned aquiferhostedinsand ed inthearea. The aquifer cial aquiferandthe ned aquifers the lastfew years,have resultedinsaltwater intrusion prolonged droughtsthathave affl municipal andagriculturalwater demandduringthe Groundwater overabstraction tomeettheincreasing groundwater resourcestohave beenpoorlymanaged. measurements, conductedwithaGIS,hasshown electric conductivity, temperatureandwater level base setup. Analysis ofthedata,consistinginpH, wells. Earlierdatawerere-organized andadata and deepwells,chosenfromamongtheinventoried network setupcomprisingmorethan200shallow to thesouthernpartofplainandamonitoring et al.,1995).Inearly2003thestudywas extended in 1979wereretrieved andanalyzed1979(Barrocu at CagliariUniversity in1990,but datacollectedback commenced bytheDepartmentofLandEngineering Monitoring inthenorthernpartofplainwas Saltwater intrusion has beenestimatedtobe298mm/year. calculated fortheplain(Staffa, 2003)aquiferrecharge bordering theplain.Basedonwater budget by lateralinfl due totheresidualrunoff, rainfall andirrigation, present theaquifersystemisfedbydirectinfi Figure 32-Isosalinitycurves (µS/cm)for thedeep ow fromthevolcanic rockaquifers aquifer (after Salis&Soddu,2003). icted Sardiniaover 26-05-2004, 11:08:30 ltration HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

in increasingly larger areas. The determining cause is to be sought in the gradual lowering of the groundwater table. In those surfi cial aquifers where the water table has dropped signifi cantly, an increase in groundwater electric conductivity has also been observed. Water table lowering is more pronounced in the summer months and less pronounced inland. Water levels indicate both for the surfi cial and deep aquifers that the groundwater fl ows primarily from inland towards the coast, with local inversions due mainly to the presence of pumped wells. Note that the Figure 33 - The ruins at Tharros. hydraulic gradients also diminish towards the coast. Arrubia lagoon and along the River Tirso mouth. In Figures 31 and 32 show the salinity contour lines for the latter area high electrical conductivity was also the surfi cial and deep multi-layer aquifers measured observed in the surfi cial aquifer. in spring 2003. Summing up, monitoring and the hydrogeological As can be observed, salinity levels throughout the studies carried out in the plain allowed us to: plain are well above the 400 µS/cm established by Italian Law for drinking water and in vast areas - ascertain the existence of groundwater salination exceed 2000 µS/cm, the limit value for the majority processes and track their temporal evolution; of crops grown in the area. - identify the most vulnerable zones; in particular The isosalinity curves in the surface aquifer exhibit it has been observed that on the whole the surfi cial a fairly irregular pattern, the higher values being aquifer is more severely contaminated than the observed along bands lying pseudo-perpendicular to deeper one. the coast. This appears to suggest that preferential pathways exist, probably consisting of formations Based on the hydrogeological data and with higher permeability through which the seawater hydrogeochemical and isotope analyses, a GIS encroaches inland. supported model has been developed. Using a three- Concerning the multi-layer aquifer, the highest dimensional fi nite element code (CODESA 3D), salinity values have been observed along the coast, simulating coupled fl ow and solute transport processes and local anomalies have also been found inland. in variably saturated porous media, a model has been This suggests that the cause of salination may be defi ned, by means of the calibration-validation attributed to seawater intrusion only in the coastal process, that can also be used for predictive purposes, area. Inland, the salinity may be caused by other aimed at integrated water resources management. phenomena such as upconing, dissolution of

unleached salts present in the aquifer formations P37 to P54 n° 5 - from Volume and the presence of subsurface seawater that has infi ltrated through the ground in past geological eras. As can be observed in the deep aquifer the salinity peaks are higher than in the surfi cial one but only in small zones, electric conductivity remaining below 1000 µS/cm in vast areas. Furthermore the most contaminated areas were found south of the S’Ena

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu the V andtheIIIcenturyB.C.they alsousedtowork premises wherethecraftsmenworked coral.Between cold water, thetemples,living quarters,andthe with dressing-rooms,saunas,poolshotand houses withtheremainsofthreesystemscomplete the tombs,aqueduct,water tank,thebath and otherevidence ofRoman occupation, suchas Of majorimportancearethepaved Roman roads Marseille. Museum inLondonandtheBorely discovered arecurrentlyconserved intheBritish light theremainsoftown. Infact partofthefi later FrenchandEnglisharchaeologistsbroughtto Excavations duringthelastcenturybyItalianand in 1070,afterashortreturn1052. inhabitants wereeventually forcedtoleave thetown Saracens alsostagedaseriesofincursions. The headquarters. Betweenthe VIII andIXcenturythe Byzantine dominationitbecametheBishop’s onwards, was raidedbythe Vandals. Duringthe became acolony but, fromthe V century During theRomanEmpireterritory the existing buildings. structure intact,expanding thecityaround around 238B.C.,leaving theformerurban century B.C. The Romanssettledinthearea on anorganised urbanstructureinthe VI thanks totheCarthaginiansthat Tharros took became aRomansettlement.Butitwas Following Phoeniciandomination,thetown previously inhabitedbytheProto-Sardinians. B.C. bythePhoenicians,but theareawas Tharros was foundedinthe VIII century Mediterranean. the mostimportantarchaeologicalsitesin San Giovanni diSinis(Figure33),areoneof The remainsoftheancientcity Tharros at Marco, 217Oristano. Geological maps 528 sect.ICabras,IIOristano,IIICapoSanMarco. Topographic maps Recommended maps guided visittothearchaeologicalsiteat Tharros. The routeproceedsalongapaved road.One-hour General information ontheitinerary From Arborea toSanGiovanni diSinis(10Km). Stop 5.1: –Sheet1:100,000:216CapoSan –IGMtables1:25,000,series25: DAY 5 nds fi lagoon aboundswithhighlysoughtafterspeciesof birds, includingpinkfl signifi an importantnaturereserve ofmajorenvironmental lagoon atCabras,oneofthelargest inEurope,is Aside fromtheculturalandtouristattractions, granules. of Is Aruttas andMariErmicomposedoftiny quartz S. Giovanni diSinisarethesplendidsandybeaches by thenearbyseaandsanddunes. To theNorthof The siteissituatedinabeautifulsetting,enhanced archaeological sitethereisalsoaNuragicvillage. there childrenwhodiedofnaturalcauses.Nearthe are believed tohave sacrifi to have sacrifi of thetophet,wherePhoenicianswerethought To theNEofexcavated areasstandtwo altars interest. carved intothesandstonerockarealsoofgreat and monolithictempledatingtothePunicperiod The Proto-Christianchurch,Phoeniciannecropolis temperatures. discovered wherethemetalwas meltedatvery high iron, andinfact anumberoffurnaceshave been 547 sect.III Villacidro. Topographic maps Recommended maps The routeproceedsalongtheasphaltroad. General information ontheitinerary From SanGiovanni diSinisto Villacidro (58Km). Stop 5.2: sh. cance. Itsbanksarepopulatedwithaquatic ced children,even thoughtodaythey –IGMtables1:25,000,series25: amingos (Figure34)andthe ced animals,andplaced Figure 34–Flamingos. 26-05-2004, 11:08:36 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

Geological maps – Sheet 1:100,000: 225 Guspini. producing a series of frequent, approximately N-S Because of its position, nestled between the rocky trending narrowly spaced tension cracks (“ac- eastern spurs of the lglesiente range, Villacidro joints”). is described as the only “mountain” town in the The area forms part of the western fl ank of the Campidano. In the charming old centre stands the Campidano Graben of south-western Sardinia. Along art nouveau public fountain. Various excursions can this fl ank a rather connected tectonic pattern appears be made into the mountains, starting from the State in the rocks. Lateral as well as horizontal movements forests at Montimannu. were released as distinct fracture zones. Thus shear The rugged slope borders with M. Linas and is movements along approximately N-S fracture thickly wooded. The Rio Muru Mannu and Rio Linas planes dissected the rock almost perpendicularly waterfalls are the highest and most spectacular in to the longitudinal axis of the valley of Villacidro. Sardinia. Obviously, these movements, associated with the From the summit of the reliefs, one can enjoy a Campidano tectonics, were steered in this direction magnifi cent view of the entire Campidano plain and by previously existing ac-joints. Along the sides of the the lglesiente and Sulcis mountains as far as the sea. valley shear joints are frequent, showing secondary Nearby are the archaeological remains of a Punic movements along the direction of the valley. temple, Nuraghe huts and three temples with wells, According to the basic theory for groundwater which are hidden from view. A kilometre and a half occurrence in hard rocks, major fractures are from the town, is the waterfall of Sa Spendula. presumed to contain groundwater. However, earlier investigations had demonstrated that shear fractures Villacidro is situated at the mouth of a small caused by weak shear movements, are very often catchment surrounded by the steep mountains of M. compressed and consequently tight, or in any case Omo to the North, M. Cuccuru Frissa to the South, make poor aquifers. On the other hand, shear zones and M.s’Enna de is Forrus to the West. During the with major displacement were found to be so heavily dry season, the basin is drained eastwards by a small brecciated as to be considered gravel structures. stream. In the upper part of the valley there are several In this case they act as highly productive aquifers, springs, developed for the town’s water supply. At the especially when rotational movements have occurred mouth of the valley are some shallow wells and some during the shear process. In fact, rotation very often groundwater seeps into the river bed. In the middle opens up the fracture zone, increasing total free pore of the valley no springs or groundwater seepage are space signifi cantly. evident. According to our working hypothesis, both tight and The summits of M.Omo and s’Enna de is Forrus consist open shear fractures occur in the valley of Villacidro. of hornfels schists of Devonian to Carboniferous age, The tight shear is presumed to have occurred along produced by thermal metamorphism of shales and the bottom of the valley, indicated by secondary phyllites at the contact with the granite (Barrocu et shear planes on the rocky sides of the valley. al., 1974). The open shear is thought to have cut the valley, A medium- to coarse-grained granite occupies almost perpendicularly, between two blocks. This the lower part of the area, gradually passing to assumption, based on the result of seismic surveying, microgranite at the summit. Generally, the coarse- was confi rmed by drilling operations carried out in grained granite appears more weathered than a low velocity zone in the middle of the valley. A microgranite. The two types differ only in texture, borehole drilled down to -65 m in the tight shear zone as both consist of quartz, orthoclase, biotite and yielded only 0.13 l/s (470 l/h). The cataclastic granite muscovite. was weathered down to -55 m. Both the granite complex and schists are crossed by An inclined well (75°) was drilled in the valley bottom P37 to P54 n° 5 - from Volume swarms of small quartz veins, usually 1-3 m wide. in a zone located by extrapolating the direction of the A vertical, 1-m-wide, N85°E-S85°W-striking vein is shear between the two blocks in the northern side, locally mineralized with Pb, Zn, and oxidized ores. so as to strike the fracture zone below the assumed The granite rock body is dissected by a joint system, groundwater table, at a depth of about 20 m. The indicating that the granite was deformed, probably fracture zone was struck by the inclined borehole at rather close to its intrusion, in a N-S direction. This -41 m; drilling operations had to be interrupted at deformation gave rise to stress in E-W direction -51.7 m, in the fracture zone, because of the strong

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Volume n° 5 - from P37 to P54 P37 - P37 Figure 35-TheCapoterraalluvialplain. Leader: G.Barrocu 20 mbelow thenaturalwater table. zone yielded1.1l/s(4000l/h)withastabledrawdown l/h). A vertical boreholedrilledinthesamefracture with astabledrawdown of13mgave 0.5l/s(1800 groundwater infl Information System(G.I.S.)was setup,creatingan for theCapoterraalluvialplain,aGeographical On accountofthelarge amountofdatacollected 1998). (Sciabica, 1994;Barrocuetal.,1997, system andtonumericallysimulatethephenomenon insight intosaltwater intrusioninthecoastalaquifer The purposeoftheinvestigation was togainadeeper and AVICENNE 73,funded bytheEuropeanUnion. the frameofinternationalprojectsMEDALUS of LandEngineeringatCagliariUniversity, within and Applied GeophysicsSectionoftheDepartment has beencarriedoutbytheEngineeringGeology A comprehensive studyoftheCapoterraalluvialplain 234 Cagliari. Geological maps sect. IIICagliari,556II Assemini. 565 sect.ICapoterra,566IVLaMaddalena,557 Topographic maps Recommended maps The routeproceedsalongapaved road. General information ontheitinerary From Villacidro toCapoterra(46Km). Stop 5.3: ow. The wellpumpedfor30hours –Sheet1:100,000:233Carbonia, –IGMtables1:25,000,series25: as toevaluate thehydrogeologicalparametersfor wells oratpurposelybuilt wellsandpiezometersso Pumping testswereperformedatselectedobservation in thelaboratory. from somesignifi month inallthewellsandwater samplescollected ’92 and’93,groundwater levels weremeasuredeach to includetheareanearerCixerri river. In1991, river, andthenextended northwards in April ’92soas the southernportionofplain,nearSantaLucia groundwater level was setupinJune1991,initially monitoring network forcontrollingwater qualityand the shallow partofthecoastalaquifersystem. A widespread salination,withmoreseriouseffects in the depletionofgroundwater resourcesandintheir indiscriminate overexploitation, have resultedin from thesalt-works andsalt-hills),combinedwith (sea spray, seawater, lagoon,evaporation ponds various naturalandanthropogenicsourcesofsalt periods ofdrought,aswellthepresence the area,characterizedbyfrequentandprolonged accordingly. The particularclimaticconditionsof industrial expansion andwater demandhasincreased profound transformationsduetoagriculturaland Over thelasttwo decades,theareahasundergone or locallyconfi aquifer, overlaying asecondmulti-layeraquifer, semi alluvia arehighlypermeableandcontainaphreatic metamorphic schistsofthePalaeozoic. The recent alluvia oftheQuaternaryandfracturedgranites lacustrine sediments,recentandancientterraced been identifi the area,following hydrogeologicalunitshave geomorphological, andpedologicalinformationfor Based onthegeological,hydrogeological, 35). sets ofNW-SE andNE-SWtrendingfractures(Figure west oftheSardinianGrabenissplitupbytwo main representing theextension ofthetectonicblockthat interrupted byaseriesofhillsalignedenéchelon, northwards bytheCixerri river. To the West itis bounded eastwards bytheSantaGillalagoonand Santa Luciariver, atorrentialwatercourse, andis Sardinia. Itcomprises,totheSouth,deltaof western portionoftheCampidanoGrabeninsouthern The Capoterraalluvialplainissituatedinthesouth- Field investigations andmonitoringnetwork system (Barrocuetal.,2001). modelling saltwater intrusioninthecoastalaquifer database, soastoallow forintegrated methodsin alphanumerical databasetogetherwithageographic ed (Barrocuetal.,2000):fl ned. cant wellswerechemicallyanalyzed uil and uvial 26-05-2004, 11:08:39 HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

Figure 36 - Water level contour lines (January ’93). Figure 37 - T.D.S. contour lines (January ’93).

simulating saltwater intrusion. and monitoring network, were used for constructing Artifi cial recharge experiments were also carried graphic representations such as piezometric contour out at purposely built wells and piezometers in the lines, Schoeller’s diagram, Chebotarev’s diagram, plain so as to assess the effi ciency of a hydrodynamic T.D.S. contour lines, and so on (Barrocu et al., 1994, barrier aimed at controlling saltwater encroachment Barrocu et al., 1994). and its spatial evolution (Barrocu et al., 1997). The water level contour lines for January ’93 (Figure

More recently, in July 1998 a measurement campaign 36) show that both aquifers are recharged laterally P37 to P54 n° 5 - from Volume has been conducted in the frame of a detailed study of by groundwater through the granite bedrock at the the groundwater geology and geochemistry (Vernier, western boundary of the aquifer. Supply probably 1999). takes place through preferential pathways in the form of the main fracture systems occurring in the bedrock. Hydrogeological and hydrogeochemical In both aquifers there is a depression of piezometric investigation results surface to below mean sea level coinciding with The hydrogeological and hydrogeochemical data, groundwater over-exploitation to satisfy agricultural collected during measurements taken in the control and industrial demand. Depressions are located

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu aquifer isnotassalinatedthephreaticone.In the increaseinirrigationdemand.Inmain,deep summer thesituationnearcoastisexacerbated by remains practicallyunchangedthroughouttheyear. In of theplainandnearborderwithsaltworks piezometric heads.Salinationintheeasternportion the values increase,coinciding withthelowest east (wherethesaltworks andlagoonarelocated) salt content;tothesouth(coastalzone)and from thewesternsideisindicatedbylowest for bothaquifers.Recharge intothephreaticaquifer Figure 37shows theJanuary’93 T.D.S. contourlines observed inproximityofthecoast. and thesaltworks. Low piezometriclevels werealso mainly inthecentralpartofplain,nearlagoon (January ’93). Figure 38-Calibration-validationofflow equation The hydrogeologicalmodel the modelhasbeensuccessfullyvalidated. simulation performed,repeatingthisprocedureuntil made atthevarious modellingstagesandfurther satisfactorily validated, adjustmentswillhave tobe determinations (Sciabica,1994).Ifthemodelisnot validation usingfi of themathematicalmodel,itsnumericalsolutionand hydrogeological andconceptualmodels,formulation coastal aquifersysteminvolves thedefi saltwater intrusionprocessesintheCapoterra The modellingprocedureappliedforsimulating Modelling saltwaterintrusion an increasingtrend. round, whileinthewesternpartofplainitexhibits piezometric surface, salinityremainslow allyear abstraction resultsinsignifi central partoftheplain,whereintensegroundwater The mathematicalmodel take placewithinthedomain. and propertiesoftheporousmedium,processesthat dimension andgeometryofthedomain,composition study, introducingseveral assumptionsconcerning simplifying thedomainandphenomenonunder The numericalsolution the mathematicalformulation. Cauchy boundaryconditionsareaddedtocomplete concentration. InitialandDirichlet,Neumann,or density ofthefreshwater-saltwater mixturetosalt by meansoftheconstitutive equationrelating equation). Flow andtransportequationsarecoupled conservation forthesaltcontaminant(thetransport salt solution(fl one describingmassconservation forthewater- coupled systemoftwo partialdifferential equations, Processes infl has beenestablishedbyprocessingpiezometricdata. between groundwater, lagoon,saltworks andsea development ofthestudyarea. The relationship irrigated agricultureandtheurbanindustrial saltworks, andanthropogenicfactors including proximity ofthesea,presencelagoonand identifying boththenaturalfactors, suchasgeology, The conceptualmodel water samples. correlation betweenchemicalelementspresentinthe aquifer systemwereelucidatedbyexamining the differences; thenon-linearcoupling isresolved approach, andtimediscretizationusingfi the fi equations involves spatialdiscretizationusing nite elementmethodaccordingtoGalerkin’s uencing water salinityinthecoastal ow equation),andtheothermass eld measurementsandchemical codeofthesenon-linear hasbeendefi canbeformulatedasa cant depressionofthe hasbeendefi nition ofthe nd by ned nd by ned 26-05-2004, 11:08:45 nite HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

fairly well reproduced with our calibration-validation procedure. Figure 38 shows the lateral recharge from the western boundary of the domain, the preferential fl ow direction towards the lagoon, the saltworks and the sea, and the zero contour line coinciding with the drawdown cones of some wells near the lagoon (phreatic aquifer) and the saltworks (confi ned aquifer).

The T.D.S. contour lines plotted using the calculated data (Figure 39) and the fi eld data for January ’93 show a similar trend.

Organization of the G.I.S. On account of the large amount of data collected for the Capoterra alluvial plain a Geographical Information System (G.I.S.) was set up, creating an alphanumerical database together with a geographic database (Barrocu et al., 2001). The information collected in the monitoring network over the years of measurements was organized into an alphanumeric database, created with Microsoft Access software. To facilitate input, modifi cation and above all the display of the information contained in the database, masks were created for “coordinates and elevations”, “water levels” and “chemical analyses” for each month of measurement, and “pumping tests”, linked together by action keys. In each mask it is possible to search for information concerning a specifi c well, to access the other masks, to print the report of the data, after preview, and to return to the last mask displayed.

The geographic database, created with ESRI Arc Info and Arc View software, organizes all the information Figure 39 – Calibration-validation of transport equation collected in the Capoterra alluvial plain into a number (January ’93). of views and themes: • a view that contains levels of general information using a Picard iteration method, which subsequently that were created from .DXF fi les in AutoCAD solves the fl ow and transport equations (Sciabica, and imported and converted into ArcInfo 1994; Paniconi and Putti, 1995). The results from the coverages and ArcView shape, i.e., geology, numerical code are expressed in terms of equivalent elevation, surface hydrography, monitoring freshwater heads and normalized concentrations at network;

selected time intervals and at each node of the three- • as many views, constructed querying the Access P37 to P54 n° 5 - from Volume dimensional mesh. database by using an SQL connection feature, as The calibration-validation of the numerical solution there are months of measurement, containing the code is performed by comparing the simulation information on water level, T.D.S. and electric results with hydrogeological and hydrogeochemical conductivity contour lines of the phreatic and data obtained from the monitoring network (Sciabica, confi ned aquifers, and the spatial distribution of 1994, Barrocu et al., 1997, Barrocu et al., 1998). the principal physico-chemical parameters, such The water level contour lines for January ’93 could be as temperature, pH, cations and anions;

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu piecework creatingruthlesscompetition amongthe was wellstage-managedasthey werepaidby was, however, seasonalwork, andworker exploitation saltworks was agreatboosttothevillage’s economyIt In the1920sopeningofMacchiareddu bridges collapsedforonereasonoranother. non-existent and ofteninterruptedwhentheScafa Cagliari, publictransportatthetimewas practically communication routes. Though relatively closeto still geographicallyisolated,andfar fromthemain beginning ofthiscentury, whenthevillagewas to overcome thediffi a healthhazard)gave many families theopportunity this village.Miningoperations(even ifarduousand until itsclosurein1963,boostedtheeconomyof last century, andremainedidle forvarious periods This mine,whichwas soldtowards theendof as labourers,thenminers. adapted toworking inthenew miningcomplex, fi the previous century. SomeoftheCapoterrapeople which hadbegun inEnglandatthebeginning of the amazinginnovations oftheIndustrialRevolution, Capoterra weremaybethefi machines”) wentintooperation,theinhabitantsof furnaces andsteelworks oftheNavy andofthesteam Marina edelleMacchinea Vapore” (“Company ofthe the “Compagniadegli Alti Forni e Acciaierie della Petin Gaudetcompany fromParis, andproprietorof In 1860,whentheS.Leonemine,owned bythe agriculture andcattlefarming. Up tothemid1800seconomywas basedon Pauliara, atthefootofMountSantaBarbara. shape in1966,thelow hillsofSaBirdieraand developed intheearly1960s;thirdbegan totake from MaddalenauptoCalad’Orriandstartedbe Arrubiu. The secondrunsalongthecoastalribbon of thehillsMontarbu, PuntaSaLorigaandMount around aseventeenth-century village,liesatthefoot The formerbuilt up area,theoldest,whichexpanded three distinctsettlementsaboutfi town planning. Today itsterritoryisdivided upinto increases ontheislandandamajortransformationin its suburbs hasseen oneofthehighestpopulation Over thelast10yearstown ofCapoterraand •aview containingthelevels ofinformation procedure andthesimulations. the aquifersbothforcalibration-validation the equipotentialandequiconcentrationlinesof results includingthetwo-dimensional mesh, created fromthesaltwater intrusionmodelling cult economicsituationatthe rstinSardiniatowitness ve kilometersapart. rst their own unemployed. of Assemini andSarrochpreferredtogive work to specialization andbecausetheEmployment Agencies agreement andlow salaries,becauselacked proper forced towork forcontractors,withnosafety But formany yearsthepeopleofCapoterrawere and Macchiaredduagain kindledhopesforrecovery. The arrival ofthepetrochemicalindustryatSarroch the leftwingparties. Today itisprohibited. even regulated byaregional law, withthesupportof unemployment problemsintheareabird-trappingwas the closureofS.Leonemine,tocopewithheavy trapping, usedinthepastduringdiffi traders resortedtothetraditionalpracticeofbird- To make upforthis,inthepost-war yearssome effects ofthewar andrecovery was noteasy. the fascist periodwas neutralizedbythedeleterious teams ofsaltcollectors. The agriculturalboomduring for checkingouttheproposeditineraryinfi Special thankstoourtechnician,Mario Avelino Sitzia, scientifi Oristano plainandtoMariaGraziaSciabicaforthe Soddu andNicolaSalisforthepartconcerning the Orgosolo-Oliena-Urzulei Supramonte,toSamuela Francesco Sannaforhisreportonthekarstifi and forthescientifi organising thefi guidebook. Particular thanksgotoFederica Ardau for of Territorial Engineeringforhaving preparedthis Geology and Applied GeophysicsattheDepartment to hiscollaboratorsattheSectionof Applied The supervisor, Prof.Giovanni Barrocu,isindebted Acknowledgements Muravera plain(SESardinia,Italy). confi Ardau, F. andBarbieri,G.(2000). Aquifer Muravera in acquiferi costieridellapianadiMuravera. Included Ardau, F., Barbieri,G.,Barrocu,G.(1996).Gli Torino,Univ. ofCagliari. (Sardegna sud-orientale). delle acquesotterraneenellapianadiMuravera Ardau, F. (1995).Studiodeifenomenidisalinazione Water IntrusionMeeting of Muravera (South-EasternSardinia). phenomena ofsaltwater intrusioninthecoastalplain Ardau, F. andBarbieri,G.(1994).Evolution of References cited Notes ofnew Geological Sheet1:50.000,549– guration andpossiblecausesofsalinationinthe c reportontheCapoterraplain. , ServizioGeologicod’Italia,pp.111-116. eld tripandcompilingtheguidebook, creportontheMuravera plain,to , 305–312. Ph.D. thesis cult times. cult With 16th Salt Water , Politecnicodi ed areaof 13th Salt 26-05-2004, 11:08:50 eld. HYDROGEOLOGY OF THE ISLAND OF SARDINIA (ITALY) P37

Intrusion Meeting, 11-18. Proc. of 13th Salt Water Intrusion Meeting, 77-86. Ardau, F., Balia, R., Barbieri, G., Barrocu, G., Barrocu, G., Ghiglieri, G., Uras, G. (1995). Intrusione Gavaudo’, E., Ghiglieri, G., and Vernier, A. (2000). salina e vulnerabilità degli acquiferi costieri nella Geophysical and hydrogeological studies in a coastal piana di Oristano (Sardegna centro – occidentale). plain affected by saltwater intrusion. SAGEEP 2000, Convegno gestione irrigua in ambiente mediterraneo, Conference Proceedings, 223-231. pubblicazione n° 1383 del GNDCI-CNR U.O. 4. 12. Assorgia, A., Bentini, L., Biondi, P.P. (1967). Note Barrocu, G., Sciabica, M.G., Uras, G., Cortis, A., sull’idrologia sotterranea del “Supramonte” di Urzulei Vernier, E. (1997). Saltwater intrusion and artifi cial (Nuoro). Boll. C.A.I., 46(79), pp. 139-152. recharge modelling in the coastal aquifer system of Assorgia, A., Biondi, P.P., Morisi, A. (1968). Aspetti Capoterrra (Southern Sardinia). Proc. of Conf. on geomorfologici sul Supramonte di Urzulei (Nuoro, Water Problems in the Mediterranean Countries, Sardegna centro-orientale). Comun. X Congr. Naz. Near East University Civil Engineering Department Spel. Roma 1968, Rass. Spel. It., 25 (1-4), 139-167. Nicosia, 2.1001-2.1007, North Cyprus. Balia, R., Gavaudo, E., Ardau, F., Ghiglieri, G. (2001). Barrocu, G., Sciabica, M.G., Uras, G. (1998). Geophysical approach to the environmental study of a Transport modelling of saltwater intrusion processes coastal plain. Geophysics, vol. 68, n°5, 1-14. in the coastal aquifer system of Capoterra (Southern Bandiera, F., Cossu, A., Fois, M., Sanna, L., Cabras, Sardinia, Italy). Proc. of 15th Salt Water Intrusion S., Cabras, I., Cabras, S., Murru, A., Murru, F., Meeting, 23-27, Ghent, Belgio. (2002). Colorazione c fl uoresceina nel Supramonte Barrocu, G., Muscas, L., Sciabica, M.G. (2000). Prima tra la grotta dell’Edera (Urzulei) e la sorgente di esperienza di sviluppo di un Sistema Informativo Su Gologone (Oliena): esperienze e considerazioni. Geografi co della Piana di Capoterra (Sardegna). In: Antheo - Bollettino del Gruppo Speleo Archeologico Proc. of 4th Nat. Conf. della Federazione A.S.I.T.A. Giovanni Spano di Cagliari, n. 6, 47 - 60. (Associazioni Scientifi che per le Informazioni Barca, S., Di Gregorio, F., Palmerini, V. (1981). Territoriali e Ambientali), 1.423-1.428. Linea di costa pleistocenica nella piana di S. Priamo Barrocu, G., Muscas, L., Sciabica, M.G. (2001). (Sarrabus, Sardegna sud-orientale). Boll. Soc. Geol. G.I.S. and Modelling Finalized to Studying Saltwater It., 100, 71-84. Intrusion in the Capoterra Alluvial Plain (Sardinia- Barbieri, G. and Barrocu, G. (1984). Consequences Italy). Proc. of First International Conference of overexploiting coastal aquifers in areas of touristic on Saltwater Intrusion and Coastal Aquifers - development in South-Eastern Sardinia (Italy). Int. Monitoring, Modelling, and Management, Essaouira, Conf. on Water Res. Plann. and Manag., 1-12. Marocco. Barbieri, G., Barrocu, G., Ranieri, G. (1986). Carmignani, L, Cocozza, T., Ghezzo, C., Pertusati, Hydrogeological and geophysical investigation for P.C. and Ricci, C.A. (1986). Guide-book to the evaluating salt intrusion phenomena in Sardinia. 9th excursion on the Paleozoic basement of Sardinia. Salt Water Intrusion Meeting, 659-670. IGCP, Project N° 5, Correlation of variscan and pre- Barrocu, G., Houtkamp, H., Jacks, L., Larsson, I. et variscan events of the alpine-mediterranean mountain al. (1974). Geohydrological investigations of ground belt, fi nal meeting, Sardinia, Pacini Editore, , water in granite rocks of Sardinia. Rep. Inst. för 1-102. Kulturteknik, 3:15, 1-74, Stockholm. Civita, M., Cocozza, T., Forti, P., Perna, G., Turi, Barrocu, G., Larsson, I. (1977). Granite tectonics at B. (1989). Idrogeologia del bacino minerario ground water prospecting in southernmost Sardinia. dell’Iglesiente (Sardegna Sud Occidentle). Mem. Geohydrol. Invest. of Ground Water in Granite Rocks Ist. It. Speleologia, ser. II, 2, 1-137, Carta Idrogeol., of Sardinia, II. Rep. Inst. för Kulturteknik, 3:21A, 3- Roma.

27, Stockholm. Civita, M., Manzone, L., Olivero, G., Vigna, B. P37 to P54 n° 5 - from Volume Barrocu, G., Fidelibus, M.D., Sciabica, M.G., Uras, (1992). Approcci sinergici nelle ricerche sui sistemi G. (1994). Hydrogeological and hydrogeochemical idrogeologici carbonatici del Piemonte meridionale. study of saltwater intrusion in the Capoterra coastal Atti del Conv. “Ricerca e protezione delle risorse aquifer system (Sardinia). Proc. of 13th Salt Water idriche sotterranee delle aree montuose”, Brescia Intrusion Meeting, 105-111. 24-25/10/1991, 53-86. Barrocu, G., Sciabica, M.G., Paniconi, C. (1994). Cocozza, T. and Jacobacci, A. (1975). Geological Three-Dimensional Model of Saltwater Intrusion in outline of Sardinia. Reprinted from Geology of Italy, the Capoterra Coastal Aquifer System (Sardinia).

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Volume n° 5 - from P37 to P54 P37 - P37 Leader: G.Barrocu Goliardica Pinna, M.(1954).IlclimadellaSardegna. Géologique deFrance of North-CentralSardinia. Pasci, S.(1997). Tertiary transcurrenttectonics 170. intrusion aquifers. linearization forthecoupletmodelofsaltwater Paniconi, C.andPutti,M.(1995).PicardNewton Journal ofHydrology hydraulic calculationsandisotopicdatingreply. stead inisolatedaquifers:implicationsrelatedto Mazor, E.&Nativ, R.(1994).Stagnantgroundwater CO EDISAR–Cagliari. Fadda, A.F., Pala, A. (1992). SAR –Cagliari. Sardegna – Fadda, A.F. (1990).L’evoluzione delpaesaggioin Fotografi Editice Archivio Colomo, S.(1992). Fotografi Editice Archivio Colomo, S.(1987). the Libyan Arab Republic, Tripoli, 49-81. Edited byCoy Squyres, The EarthSciencesSocietyof , Pisa,1-104. Geomorfologia eidrografi a Adv. in Water. Resour. Guida al Trekking inBarbagia Sardinia – A seaofitineraries , 154,409-418. , 168(3),301-312. co Sardo–Nuoro. co Sardo–Nuoro. Le acquedellaSardegna Bulletin delaSocièté , 18(3),159- . COEDI Libreria . . . thesis alluvionale diCapoterra(Sardegna meridionale). idrogeochimico delsistemaacquiferodellapiana Vernier, E. (1999). Studioidrogeologicoed Univ. ofCagliari. monitoraggio. dati idrogeologiciedidrogeochimicidelleretidi concettuali ematematicidegli acquifericoni Sciabica, M.G.(1994). Validazione deimodelli 6, 29-46. Speleo Archeologico Giovanni SpanodiCagliari ed idrogeologia. carbonatica delSupramonte:Rapportitracarsismo di SuGologonenelcontestodellaidrostruttura Sanna, F., Vernier, A., Vigna, B.(2002).Lesorgenti Ph.D. thesis Orgosolo-Urzulei (Sardegna Centro-Orientale). riserve idrichestrategiche nelSupramontediOliena- Sanna, F. (1995).Individuazione diimportanti 28, 645-652. Centro-Orientale). “Supramonte diOliena-Orgosolo-Urzulei” (Sardegna sull’assetto geo-strutturaleedidrogeologicodel Sanna, F. and Vernier, A. (1993).Studiopreliminare , University ofCagliari. , Politecnicodi Torino, Univ. ofCagliari. PhD thesis Antheo -BollettinodelGruppo Geologia Applicata eIdrogeologia , Politecnicodi Torino, 26-05-2004, 11:08:53 PhD , n. , Back Cover: fi eld trip itinerary

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