Bouchaou Et Al 2002

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ouchaou, L., Qurtobi, M., Hsissou, Y. and Boutaleb, S. 2002. The underground river of Win)Timdouine (Agadir region, High Atlas): a contributiono the inventory of the geological heritage in Morocco. ln: Carrasco, F., Durn, J. J. YAndreo, B. (Eds.) Karst and Environment. 273-2791he underground river of WincTimdouine(Agadir region, High Atlas): a contribution to the)inventory of the geological heritag~e in Morocco

L. Bouchaou(l), M. Qurtobi(2), Y. HsissoU(l) and S. Boutaleb(3)uLaboratoirede GologieAppliqueet Go-environnement,quipe d'Hydrogologie,UniversitIbnZohr,FacultdesSciences,BP28/S,~80000 Agadir, Maroc (Bouchaou1 @caramail.com)Section d'Hydrologie Isotopique, CNESTEN,5 rue Tensift, Rabat, MarocGEOATLAS,BP. 373, Laayoune Sahara, Maroc

RESUMENEl roWin Timdouine es el ms largo de los ros subterrneos conocidos en frica. Se ha explorado en 19 km de desarrollo y la ~n-gitud de su canal principal es de 9 km. Su complejo trazado muestra una perfecta adaptaci6n a la estructura geol6gica de la regi6nde pliegues de Ida Outananes. Las principales formaciones karstificadas son las dolomas yesferas de edad Jursica, en las que sedesarrolla la red subterrnea dei Wim Timdouine. A pesar de situarse en un contexto semirido, el ro mantiene su caudal median-te la recarga par infiltraci6n de aguas provenientes dei exokarst (dolinas y lapiaces) de la Cuenca de Tasroukht, donde la presenciade tobas y concreciones sugiemadems una considerable disoluci6n dei interior dei macizo. La organizaci6n lineal de la red de cir-culaci6n subterrnea, coincidiendo con fallas y fracturas y el rpido aumento de caudal en pocas de aguas altas sugieren una rpi-da circulaci6n dei agua y por ianto, una alta vulnerabilidad dei acufero frente"a la contaminaci6n. El estudio dei ro es atractivopara espele610gos y cientficos, ya que la exploraci6n de las galeras laterales es interesante desde el punto de vista biol6gico e hidro-geol6gico. Asimismo, la explotaci6n de la zona tiene un alto inters econ6mico, tanto desde el punto de vista dei abastecimientode agua para la poblaci6n, como turstico, pudiendo suponer un impulso al desarrollo de la regi6n de Agadir.Palabras clave: Alto Atlas, endokarst, fallas, Marruecos, patrimonio geol6gico, ro subterrneo '"

ABSTRACT 7The Win Timdouine river constitutes the longest underground' river known ~inAfrica. It is explord on 19 km and the length of,themain arm is about 9 km. Its complex structure shows a perfect adaptation to the regional geological structure of the folded zone ofthe Ida Outananes region. The main karstified formations are the chalky dolomite of the Jurassic range. The underground network ofWin Timdouine isdeveloped on these formations. The waterproof bottom consist of oxfordian maris. ln spite of its situation in a semi-arid context, this underground river has never dried up. Its discharge to the outlet shows considerable varia~ions indicating a karsticspring feature showing an immediate response of rainfall event. The recharge of the river takes place by the pluvial water infiltrationfrom the surface ofthe Tasroukht basin that present karstic forms like lapiaz, doline and shallow hole. The presence of important mas-ses of tufa in the outlet river and the chalky precipitation in the underground cave, indicates a considerable dissolution and therefo-re a development of karstic network in the massif. The network of circulation weil organised along of the faults and fractures and thefast increase of discharge during high waters period are the evidence for a fast circulation, which incites to water protection againstail pollutionagent.Thestudyof underground river ofWin Timdouine is interestingforspelunkersasweil as forscientists,to exploreseveral undiscovered lateral galleries and to complete hydrogeological and biological observations. ln an other side, the exploitationof the site present a considerable interest for the development of the region. ln addition ofthe exploitation of resource water to supplythe surrounding population, the site constitute a privileged tourist, that will probably know a remarkable flight in the touristic regionof Agadir.

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Keywords: endokarst, faults, geological heritage, High Atlas, Morocc:>,underground river1. INTRODUCTION The landscape is armed by cliffs of Jurassic that edg~some straightened anticlinal valley. They draw perchedvast synclines oriented E-W.The whole represents a reor-ganization of the sedimentary cover on a network ofdeep faults inherited fram the hercynian oragenesis. Theshapes large and flat synclines is especially representedby the Ait Mansour plateau. This one is pralonged at theEast by the Tasraukht plateau. This last having an avera-

The Tasroukht plateau is a part of Ida-Or-Tananes regionsituated ta 70 km in-the N-E of the Agadir city (fig. 1).The range elevation above sea level fram 1200 ta 1600m, permits a wintry rainfall with average more than 400mm/y which maintains recharge of aquifers and superfi-cial flows.273


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v.-=.F-1-"0 100 200 km

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Figure1. Situation map and springs of the Imouzzer region

1- S.Tifnit2- S.Aksri3- P.Aksri4- S.Tizgui5- S. Tougrou6- Timzguida7- S. Tamarout8- S. Imouzzer9- S. Tichkji10- S.Aoussgdelt11- S.Tenagamt12- S. Bou-Tara13-S.Timeristine14- S. Doussoulil15- S. IgniN'Blal

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aquifer system that develops on the whole of theTasroukht plateau. It gets out in the south ledge of theplateau that dominate the village of Tizghi n'chorfa (fig.2). It is also, the only access possible of an undergroundriver explored on 19 km, and that constitutes the longestunderground river known in the Africa's Northwest.

ge altitude of 1500 m, spreads on a surface of 16 km2and presents in its left a mound witness culminating to1789 m.The spring of Win Timdouine that means in Berber dia-lect "the source of the lakes" is the main outlet of the


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)The presence of mountains close to the sea-shore and"the development of caves, source, and deep gorges con-tribute to the attractin of many visitors, including bothtourists and scientists. ln this paper we describe the mainhydrogeological, structural and geomorphological featu-res of Win Timdouine River. The aim of the work is tocontribute to remark the interest of this site from the geo-logical heritage point of yiew. C'

2. METHODOLOGYOther the speleological studies which carried out bylocal and stranger speleologist club (Camus andLamouroux, 1981; Aulanger, 1987; Trillo and Marinwithout date; A.S.S and A.S.A.), we have realised manyfield observations about morphology, geology andhydrology of the Win Timdouine region. The outlet dis-charge and some parameters of spring water were mea-sured in situ. The sampling water are analysed atHydrogeology Laboratory of the Science Faculty ofAgadir. J 'ln order to determine the impact of the tectonic structu-reon the architecture and the spatial organization of thisunderground cave, we adopted the following methodo-logy:

(i) listing the set of the tectonic structures in the vicinityof the underground cave, (ii) exploration of the under-ground cave and to raise the inventory of the geologicalstructures met, and (iii) comparing the structures' under-lined.

3. KARSTIC FEATURESOF THE AREA3.1.Hydrogeology frameworkThe underground river of Win-Timdouine is developedto the basis of the chalky dolomite formation recoveringthe Tasroukht's plateau (Ambroggi, 1954). The geologicalformation since the Assif n'Tanit until the culminatingpoint belongs to the Jurassic (Ambroggi, 1963). It's ran-gjing from the upper Lias (Iimestone) to theKimmeridgian, (mari and limestone).The principal level karstified is, the dolomite limestoneof the upper Callovian, (lOto 12 m of thickness), thechalky dolomite and reef of the Rauracian - Sequanian,\(42 to 50 m of thickness). ln the basis of this last forma-tion is developed the underground network of Win-Timdouine cave. The waterproof substratum is assuredby the grey laminated maris of the Oxfordian range (20m of thickness). The morphological aspect shows animportant hydrological network with number valleythrough the karstified landscape (fig. 2).The supply of the underground river takes place by.the

infi ltration of the rainfalls from the surface of the plateauwhich contained lapiaz, doline and shallow holes. Theseimportant shapes of dissolution allows infiltrated watersto reach quickly the chalky layers and they establish aprivileged drainage network (Qurtobi et al., 2001). Thewater flow follows a synclinal axis, and constitute theunderground river that leads to the Win-Timdo~inespring by a thrust fault oriented N30 (fig. 3).This underground river shows to the outlet variable dis-charge according to the seasons, (2 I/s in low waters andmore of 1000 I/s in high waters period. This last valuecan be explained by the presence of a privileged andimportant drainage network. The average discharge isabout lOI/s. ln spite of its situation in a semi-arid con-text, this u~rground river has never dried up.The chemical characteristics show a transit of severalfamilies waters with variable progress in the time and in

\ the space. This can be explained by the complexity ofthe system, either to the presence of several entries. Itslow mineralisation (400 jJs!cm)! indicates an excellentchemical quality which dominated by a bicarbonate-calcium type (Qurtobi et al., 1994).The artif iciel tracer shows the high velocity of circulationto 60 m/h, the extent of the recharge's basin is about 24km2 (Qurtobi, 1996). The direction of the undergroundcirculations E-W is in conformity with the geological

~ data (dipping of the syncline axis westward and thegeneral raising of the eastward cover). The vertical cir-culations exist between the different chalky compart-ments that compose the aquifer (Callovian andRauracian-sequanian) in spite of their separations by aimpermeable mari of the Oxfordian range (Qurtobi etal., 1992). .The inventory trained faunal for the underground cavesince its entry until the "big room", in collaboration withthe team of research of hydrobiology of the Faculty ofthe Sciences of Marrakech-Semlalia, shows a importantand diversified population: terrestrial fauna, aquaticfauna an aerial fauna.

-3.2. Relation between tectonic and structure of theunderground riverThe Tasroukht plateau that forms the roof of the Win-, Timdouine underground cave, is a vast basin pan for'ilTwhere develops itself particularly to eastward, a marly-clays formation armed of by carbonated bars.The analy-sis of a fracturation has allowed us to distinguish fourfamilies of discontinuities of witch two are extensivelydominate:- The fractures oriented NNE-SSW, statistically verywidespread and have an important car!ographic exten-


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J. MyAli,1872m

High valleyof Tamraght

NE swTasroukht Plateau

Assifn'TanitFigure 2. Morphologie sehemes of Win Timdouine zone: important hydrologie network and valley through the karstified formations

sion. These are joints with enough often a behaviourthrusting senestral- N-W fractures, are in particular also frequent to themiddle of the synclinal structure and acquire, to thelevel of the intrados, a locally schistose character

With regard to the exploration of the underground Cill(e,we could follow the internai structuring that seems to beparallel to the one listed in the plateau, with the samedegree of importance. Therefore we can affirm that theinternai organization of the underground river is closelybound to the regional structure.

- NW-SEand N-S fractures, are less represented, someti-mes associate to the network N 30 in a setting conju- Indeed, the geometry of the underground cave is con-found with a senestre disconnection oriented N 30, dis-


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a sub-equatorial trajectory along the middle of the ('Tasroukht syncline (fig. 3). On this organisation trans-plant them selves of the latral guts and branches inN30, N-S or N140 direction. Besides, the shape synfor-me of the underground cave's roof, contributes closely tothe drainage of the meteoric waters that is transportedthrough these cracks and recharge the aquifer reservoir.This supply is also facilitated by the interface of the sedi-mentary bedding that constitutes an important migrationway. The recent speleological exploration and the field

observations show that karst forms evolve so~ly alongfaults and fractures. These observations confirm theimportance of fracturing in determining the groundwaterflow regime. Observations at the landscape scale tend todemonstrate the active role of the tectonics in the evolu-tion of this karstThe cave is explored on 19 km cumulated. The longer ofthe principal river is between 8 to 9 km (fig. 4). The pre-sence of important massesof tufa in the outlet river and

Fractures direction

_*,*,_n anticlinal Axissynclinal Axis

Underground river-. Dolines~

Figure 3. Adaptation between geology and Win Timdouine structure277


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the chalky precipitation in the underground cave, in'i-cates a considerable dissolution and therefore a deve-lopment of karstic network in the massif. The WinTimdouine river contains many spectacular karsticforms. There ismany lakes, concretion forms (stalactites,stalagmites and others).

4. A DISCUSSIONABOUT WIN TIMDOUINE INTERESTWater is the most important econo~ic resource of thiskarstic regions. Water should allow, these regions a cer-tain economic development, permitting also some reali-sations in the farming, notably agricultural and touristdomai n.

L

. For Win Timdouine, the calculated reserves are bydefault about 2 m'illions cubic meter/year. (Qurtobi,1996). Certainly, a pumping in the ''Source under theemergence level, or by boring, during the dry seasonspermits to increase considerably usable water resources.These resources are reconstituting at the rainy periods.This reconstructton even has the advantage to regulatethe rises in the Hoodwater (sometimes devastating) of theunderground river.To inform about the landscapes and their protectionmust consist for Win Timdouine, to install a receptioncenter in a strategie place for the setting in relation of apubl ic with the territory. Otherwise it wi Il be necessaryto develop a set of tools of original information that per-(

J

Figure 4. Schmatic network of the explored river278


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0mits to develop a precious sensitisation to the landsca-pe, its formation, its evolution and its stake. The protec-tion of the environment must also be discerned, to thebreasts of the caving clubs, for the same reason as theformation to the framing and the development of thesporty activities.The planning of the spaces as weil around the Tasroukhtplateau that must answer objectives that appears everytime in the politics setting of larger action of the wholezone surrounding the underground cave along theunderground river. We can mention:planning of the access roads- improvement parking and planning of reception terra-ces- enhancement of the site: against the erosion, fixing ofsoils and planning of the terraces of plantation- equipment of the cliffs, near the zone of rest, to crea-te a space of leisure and to facilitate the access to theplateau- equipment of the cave of discreet manner with a cohe-rent and adapted material to the internai structure ofthe cave, that offers a real spectacle thanks to its kars-tic curiosities (big rooms, lakes, stalagmites, stalactitesetc.)- establish a perimeter of water protection.

5. CONCLUSIONThe interest of the undergrou nd river of Wi n Timdou ineis to motivate the speleologists who have several lateralgalleries again to explore so muchf'-of the wells beinggoing back up to climb that the sientists who have tocomplete their hydrologic and biologic observations. Itconstitutes a veritable research laboratory. The presentedfeatures of the area allow to suggest a great interestfromthe geological heritage point of view. More ever, it isinteresting to notice that the majority of galleries arealigned along the principal orientation of N30 which isthe most common direction of faults observed.Investigation of Tasroukht karst allows us to observe theclose link between fractures and karstification and thedevelopment of an underground drainage system.On an other hand, it is desirable that the associationsand the scientists who are at the origin of this discoveryand this enhancement are associated to its exploitation.This last will allow the region to come out of its anony-mity and will offer many advantages to the populationwho can take advantage of it, because it is time to orga-nise some group promenades, ail along this river, what

constitutes a place of leisure for the tOUrists who arEconstantly in search of new sites as the one of WinTimdouine that certainly will know a remarkable expan-sion.

AcknowledgementsThis work is a contribution to the IGCP 448 ProjectUNESCO.

REFERENCESAmbroggi, R. (1954) Cadre gologique de la rivire

souterraine deVqtTamdoun dans les Ida ou - Tananes.Rapport du centre des tudes hydrogologiques duMaroc. Rabat, 8 p.Ambroggi, R. (1963) Etude gologique du versantmridional du Haut Atlas occidental et de la plaine duSouss. Notes et Mm. G~ol. Maroc, n 157, 322 p.Aulagnier, S. (1987) Les chauvs-souris du Maroc.Bull. Spcial Splo. Maroc 87.Camus, J. and Lamouroux, C. (1981) Inventaire sp-lologique du Maroc. Ministre Equipement. OH.,Rabat, 233 p, 104 pl. Topo., 36 photos, 2 cartes h.t.Qurtobi, M., L. Bouchaou, P.,Chauve, J., Mania, M.,Aboufirassi and Amghar, M. (1992) Structure et hydrolo-gie de l'Atlas d'lmouzzer des Ida Outanane (Agadir).ColI. Inter. Hydrogologie des milieux discontinus sousclimats arides, Revue Fac. Sci. Semlalia, section scien-ces de la terre, pp. 240-244, Marrakech.Qurtobi M., Bouchaou, L., Hsissou, Y, Chauve, P.and Mania, J. (1994) Caractristiqueshydrochimique etbactriologique des eaux des sources ge la rgiondllmouzzer des Ida-ou-Tanane (Haut Atlas occidental,Maroc). ColI. Int. Eau et PolIution, Univ. Ibnou Zohr,Fac. Sc., 23-25 avril, Agadir, pp 14-18.Qurtobi, M. (1996) Reconnaissan,ce hydrogologi-que de la rgion d'Imouzzer des Ida-ou - Tananes.Mthodologie d'tude en zone montagneuse semi-arideet non quipe. Haut-Atlas occidental, Maroc. Thse de3 me Cycle, Univ. Ibnou Zohr, Fac. Sci. Agadir, 154 p.Qurtobi, M., Boutaleb, S., Bouchaou, L., Chauve, P.,Mudry J. and Hsissou Y (2001) Apport de la gologie etde l'hydrochimie a la connaissance des phnomnes decirculations karstiques dans le haut-atlas occidentald'Agadir, (Maroc). 7 me ColI. dlhydrologie en payscalc., pp. 305-310, Besanon, France, 20-p septembre2001.Tri110,ER. and Marn, M.M. (without date) Topogra-phie de la rivire souterraine de Win- Timdouine. G.E.S.de la S.E.de Mlaga.

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Bouchaou Et Al 2002