Darmstadt, Techn. Universiẗat, Diss., 1999. / Dateiformat: tar.gz, Dateien im PDF-Format.

Th. Etat--Sc. nat.--Université de Franche-Comté, 1987. / Numéro de : "Annales scientifiques de l'Université de Franche-Comté. Géologie", mémoire 5 (1987).

Th. univ.--Géomorphol.--Bordeaux 3, 1987.

Les aquifères karstiques constituent l'essentiel des ressources en eau du pourtour Méditerranéen. Au delà de la zone saturée de ces systèmes, la zone non saturée constitue une entité importante quant au transfert et au stockage temporaire de l'eau. La structure et le fonctionnement de cette entité du karst sont complexes et mal connus à cause du processus de karstification qui hiérarchise la circulation hydrodynamique en son sein. Dans cette étude nous utilisons des méthodes géodésiques et hydrogéologiques afin d'observer de façon directe et de quantifier les processus de transfert et de stockage de la zone non saturée. Les mesures gravimétriques en surface et profondeur sur différents systèmes karstiques ont permis de quantifier les variations du stockage en eau saisonnier dans la zone non saturée. La gravimétrie différentielle montre que ces variations sont réparties dans les quelques premiers mètres de la zone non saturée. Il semble, de plus, que la capacité de stockage de la zone non saturée soit fonction de la lithologie de l'encaissant (calcaire et dolomie). Enfin, des observations directes du flux d'eau en zone non saturée ont été effectuées par le biais de mesures dans différentes cavités. Nous montrons que certaines caractéristiques du flux d'eau en zone non saturée, comme la présence d'un flux bipolaire lent-rapide, peuvent être généralisées quelques soit la profondeur de mesure et la surface d'impluvium. La modélisation de ce flux, à partir d'un schéma simple, a montré la complexité des processus de transfert engendrés au sein de la zone non saturée. / Karst systems are the most important groundwater reservoirs in Mediterranean area. Beyond saturated zone, unsaturated zone constitute an entity where water storage and transfer play a major role in a global behavior of spring water. This structure and functioning are complex and not well known because of the high heterogeneity created and organized by groundwater flow. In this study, we used gravimetric and hydrogeologic method to directly observe and quantify water storage and transfer processes in unsaturated zone of karst system. Surface to depth gravity measurements on several karst system allow quantifying seasonal water storage changes in unsaturated zone. We show that these variations occur in the first tens meters of unsaturated zone. Furthermore, water storage capacity of unsaturated zone seems to be influenced by lithology (limestone or dolomite). Finally, direct observations of water flow in unsaturated zone are done using caves access. We show that some characteristics of unsaturated water flow such as bipolar slow-fast flow can be widespread for whatever depth of measurement and recharge area. Model of this flow, using a simple modeling scheme, show the complexity of water transfer processes in unsaturated zone of karst system.

Le Liban se caractérise au sein de la Méditerranée orientale par sa diversité climatique, son organisation orographique (littoral/montagne/bassin) et la prépondérance des terrains carbonatés (60 % de son territoire). Ces caractéristiques font que le Liban connait sur un espace relativement réduit une grande diversité de phénomènes karstiques. Il constitue alors un espace-clé pour développer des référentiels tant pour les événements paléogéographiques qu'environnementaux qui puissent être appliquées sur le Proche-Orient. Plusieurs questionnements relatifs à la genèse des paysages et leur évolution restent encore non résolus face à la rareté des témoins morphogéniques de surface. L'endokarst constitue alors une nouvelle archive naturelle et environnementale pour pallier à ces contraintes. Ces archives se situent à la fois dans les formes des réseaux souterrains et dans les enregistrements sédimentaires (dépôts détritiques et chimiques : spéléothèmes). La recherche doctorale se concentre sur "l'apport des enseignements de l'endokarst dans la reconstitution des environnements passés et de la morphogénèse des vallées karstiques‘. Les sites d'études retenues dans cette recherche sont situées dans le Mont-Liban central: i) la vallée du Nahr el-Kelb et le réseau de Jeita et, ii) la vallée d'Antelias et la grotte de Kanaan et le réseau de Kassarat-Nabay. La recherche a deux principaux objectifs: i) poser le cadre paléogéographique des principaux systèmes karstiques dépendant de la Méditerranée (systèmes de Jeita et d'Antelias) à partir de l'approche géomorphologique appliquée dans les grottes de Kanaan, de Kassarat-Nabay et de Jeita. Celle-ci met en œuvre la démarche cartographique des systèmes souterrains étudiés pour replacer les différents objets d'étude dans leur contexte spatial, morphogénique et chronologique ; et ii) appréhender les changements environnementaux de cette région liés aux variations climatiques et aux occupations humaines. L'étude sédimentaire (détritique) repose sur une analyse fine (morphoscopique, morphométrique, minéralogique, colorimétrique et magnétique) des dépôts endokarstiques. / The lebanese landscape is characterized by karstic mountain chains (Mount-Lebanon and Anti-Lebanon) with a variety of surface karstic forms as well as endokarstic network systems. Karst landforms covers up to 60% of the lebanese territory. Several questions related to the morphogenesis and evolution of landscapes, espacially coastal valleys remain unsolved. Whereas geomorphic indicators are rare on the surface due to urban pressure and topgraphic constraints, we used sub-surface geomorphologic indicators revealed from the speleogenesis study of caves. Subsusrface karst network systems are an alternative mean to address these constraints and reconstitute the morphogenesis stages of the coastal valleys' landscape. Morphogeneitic and environmental reconstitution are based on both geomorphoic indiators of underground networks and on the sediments (clastic and speleothems) in caves. The PhD research focuses on "the contribution of endokarst networks in reconstituting past environments and morphogenestic phases of coastal valleys of Mount-Lebanon”. Two valleys located in the central part of Mount-Lebanon, are chosen for this study: i) the valley of Nahr el-Kelb with a study focused on Jeita cave network system, and ii) the Antelias valley two cave were selected in this sector, Kanaan cave (162 m long) and Kassarat Nabay cave network system (4,6 km long). The first objective of the study are: i) to reconstitute the stages of the karst system related with the downcutting of the Mediterranean hydrographic network (Antelias and Kelb river). The palaeogeographical framework is based on the geomorphological approach applied in the caves of Kanaan, of Ksarat-Nabay and Jeita. It implements the mapping process applied on the underground systems and analyses of the stages of cave evolution. The second objective is to understand the environmental changes in this region related to climate variations and human settlement. The study (detrital) is based on a detailed analysis (morphoscopic, morphometric, mineralogical, and magnetic color) of sediements in cave systems.

published_or_final_version / Applied Geosciences / Master / Master of Science

No description available.

Bat assemblages inhabiting two discrete karst areas in north Vietnam were sampled from 2006-2008.  Inventory studies indicate that Vietnamese karst areas with intact primary forest harbour a large proportion of the national bat fauna with levels of species richness which may greatly exceed those of other forest types in-country.  Forests on karst ridgetops in degraded areas are capable of supporting high bat species richness at low abundances and their persistence as linear tracts and latticeworks of forest in anthropogenic landscapes may provide corridors for the movement of forest-dependent bats.  Reproductive studies demonstrate that the timing of major reproductive events (pregnancy, lactation and weaning) coincide for two pteropodids and for 26 species in three insectivorous bat families.  The high temporal congruence in reproduction and climatic homogeneity of north Vietnam (18-23°N) suggests that these results may have wider applicability.  Echolocation studies involving 30 insectivorous species indicate that correct acoustic identification of free-flying bats is feasible.  Comparisons of conventional capture methods with simultaneous acoustic sampling in a variety of karst habitats demonstrate that acoustic methods are indispensable in maximising inventory completeness in assemblage studies.  Ecomorphological studies of 37 bat species indicate that analysis of wing morphology is useful in predicting foraging habitats.  Results support the hypothesis that bat species highly adapted to foraging in the forest interior are negatively affected by forest degradation.  Three bat species new to science are described.  Factors associated with extinction risk in bats are reviewed and recommendations for conservation management and further research are provided.

In karst basins, significant amounts of surface-derived sediment can enter into cave systems. The transport and deposition of these sediments in underground streams is a function of flow velocity, sediment supply and passage morphology. Changes in the surface environment can affect the water and sediment supplies to subsurface drainage systems and thus may be reflected in the sedimentary structure, texture and rates of deposition of cave sediments. Cave sediments in two south central Kentucky caves were studied to evaluate a possible, relationship between variations in deposit characteristics and variations in surface changes, including land-use. Samples were collected using coring tubes to preserve the structure within the sediment. The structure was documented visually, recording distinct changes in the layering. The textural variations were determined through sieving samples at 5 cm intervals. Passage morphology was documented through detailed mapping of the passage in the vicinity of the sediment banks. Rates of deposition were determined through Cesium and Carbon isotope analysis of the sediments and these dates were then compared to major changes in land-use in the drainage basin. It was determined that the character of sediments deposited at particular locations likely depends on the distance from the source of sediment, passage geometry and surface land use history.

This study uses high-resolution, long-term conductivity, temperature, discharge, pH, and laboratory data from 2001 through 2003 from an alpine karst spring located at 2,500 m amsl in Sequoia National Park, California to reveal detailed chemical parameters of this karst system. The data show a system with a pronounced spring run-off, extended periods of base flow quiescence, storm responses tied to precipitation as rain or as snowfall, and clear diurnal and seasonal patterns of discharge. pH and spC values show an inverse relationship to discharge and temperature, which are generally in phase. Total inorganic carbon (TIC) and the fraction of mineral-derived and biologically derived C were calculated using three methods. One provided values close to the theoretically likely ratio of 50:50 between the two C sources, while others showed ratios of greater biologically derived C, an unlikely possibility in groundwater chemistry. Saturation indices for the system vary seasonally, with base flow waters saturated at SI values between 0.2 and 0.5, and spring run-off (Q > 100 L/s) waters under saturated and chemically aggressive with SI values as low as -1.2. Late summer rain storm events can return the system to an under saturated state. The denudation rate for the marble bedrock, which makes up approximately 8% of the basin, was found to be high at 148.6 mm/1000 years. Ion and TIC flux are shown to be determined by discharge and not ion concentration.