SummaryKarst aquifers are the main groundwater resource in Lebanon as well as in most Mediterranean countries. Most of them are not exploited in a sustainable way, partly because their characteristics remain unknown. Karst aquifers are so complex that the assessment of their resource and their exploitable storage requires an analysis of their whole functioning, particularly by analysing the spring hydrograph. Among all various methods, the method proposed by Mangin aims to characterize at the same time the recharge conditions and the storage and recession of the saturated zone by analyzing the spring hydrograph. This method defines two parameters, the infiltration delay i, and the regulating power k which are the roots of a classification of karst systems. This classification makes the distinction between karst and porous aquifers considering the value of the regulating power. k is assumed to be lower than 0.5 in karst, and between 0.5 and 1 for all other aquifers, 1 being the upper limit.The study of karst aquifers in Lebanon shows values of k > 0.5, and even 1; former data from the literature show that other karst springs in Middle East have comparable characteristics. In fact, what is not considered by Mangin and others, k is equivalent to a mean residence time in years of water in the saturated zone. So long residence times are normally observed in poorly karstified aquifers, or containing abandoned, not functioning karstification. The geological framework in which the studied springs are located in fact shows that these aquifers have been subject to a long, complex evolution, as a consequence of the base level rising. This rising produced the flooding of the successive karst drainage network, which does not really function anymore and provides a large storage capacity to the aquifer. The very interesting properties of these aquifers make them prime targets for fulfilling the increasing needs of water
SummarySolute concentration variations during flood events were investigated in a karst aquifer of the Swiss Jura. Observations were made at the spring, and at the three main subterraneous tributaries feeding the spring. A simple transient flow and transport numerical model was able to reproduce chemographs and hydrographs observed at the spring, as a result of a mixing of the concentration and discharge of the respective tributaries. Sensitivity analysis carried out with the model showed that it is possible to produce chemical variations at the spring even if all tributaries have constant (but different for each of them) solute concentrations. This process is called tributary mixing. The good match between observed and modelled curves indicate that, in the phreatic zone, tributary mixing is probably an important process that shapes spring chemographs. Chemical reactions and other mixing components (e.g. from low permeability volumes) have a limited influence.Dissolution-related (calcium, bicarbonate, specific conductance) and pollution-related parameters (nitrate, chloride, potassium) displayed slightly different behaviours: during moderate flood events, the former showed limited variations compared to the latter. During large flood events, both presented chemographs with significant changes. No significant event water participates in moderate flood events and tributary mixing will be the major process shaping chemographs. Variations are greater for parameters with higher spatial variability (e.g. pollution-related). Whereas for large flood events, the contribution of event water becomes significant and influences the chemographs of all the parameters. As a result, spring water vulnerability to an accidental pollution is low during moderate flood events and under base flow conditions. It strongly increases during large flood events, because event water contributes to the spring discharge
Legends describing a Great Flood are found in the narratives of several world religions, and the biblical account of Noah's Flood is the surviving heir to several versions of the ancient Mesopotamian Flood Myth. Recently, the story of the biblical deluge was connected to the Black Sea, together with the suggestion that the story's pre-Mesopotamian origins might be found in the Pontic basin [Ryan, W.B.F., Pitman, III, W.C., 1998. Noah's Flood: The New Scientific Discoveries About the Event That Changed History. Simon and Schuster, New York]. Based on the significance of this flood epic in the Judeo-Christian tradition, popular interest surged following publication of the idea.Currently, two Great Flood scenarios have been proposed for the Black Sea: (1) an Early Holocene event caused by catastrophic Mediterranean inflow at 7.2 ky BP (initial hypothesis of [Ryan et al., 1997. An abrupt drowning of the Black Sea shelf. Marine Geology 138, 119-126]) or 8.4 ky BP (modified hypothesis of [Ryan et al., 2003. Catastrophic flooding of the Black Sea. Annual Review of Earth and Planetary Science 31, 525-554.); and (2) a Late Pleistocene event brought on by Caspian influx between 16 and 13 ky BP [Chepalyga, A.L., 2003. Late glacial Great Flood in the Black Sea and Caspian Sea. GSA Annual Meeting and Exposition, 2-5 November 2003, Seattle, USA, p. 460]. Both hypotheses claim that the massive inundations of the Black Sea basin and ensuing large-scale environmental changes had a profound impact on prehistoric human societies of the surrounding areas, and both propose that the event formed the basis for the biblical Great Flood legend.This paper attempts to determine whether the preponderance of existing evidence sustains support for these Great Floods in the evolution of the Black Sea. Based upon established geological and paleontological data, it finds that the Late Pleistocene inundation was intense and substantial whereas the Early Holocene sea-level rise was not. Between 16 and 13 ky BP, the Late Neoeuxinian lake (the Late Pleistocene water body in the Pontic basin pre-dating the Black Sea) increased rapidly from ~-14 to -50 m (below the present level of the Black Sea), then rose gradually to ~-20 m by about 11 ky BP. At 11-10 ky BP (the Younger Dryas), it dropped to ~-50 m. When the Black Sea re-connected with the Sea of Marmara at about 9.5 ky BP, inflowing Mediterranean water increased the Black Sea level very gradually up to ~-20 m, and in so doing, it raised the salinity of the basin and brought in the first wave of Mediterranean immigrants. These data indicate no major drawdown of the Black Sea after the Younger Dryas, and they do not provide evidence for any catastrophic flooding of the Black Sea in the Early Holocene.In addition, available archaeological and paleoenvironmental evidence from the Pontic region reveal no recognizable changes in population dynamics between 14 and 6 ky BP that could be linked to an inundation of large magnitude [Dolukhanov, P., Shilik, K., 2006. Environment, sea-level changes, and human migrations in the northern Pontic area during late Pleistocene and Holocene times. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 297-318; Stanko, V.N., 2006. Fluctuations in the level of the Black Sea and Mesolithic settlement of the northern Pontic area. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 371-385]. More specifically, Mesolithic and early Neolithic archaeological data in southeastern Europe and Ukraine give no indications of shifts in human subsistence or other behavior at the time of the proposed catastrophic flood in the Early Holocene [Anthony, D., 2006. Pontic-Caspian Mesolithic and Early Neolithic societies at the time of the Black Sea Flood: A small audience and small effects. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 345-370; Dergachev and Dolukhanov, 2006. The Neolithization of the North Pontic area and the Balkans in the context of the Black Sea Floods. In: Yanko-Hombach, V., Gilbert, A.S., Panin, N., Dolukhanov, P.M. (Eds.), The Black Sea Flood Question: Changes in Coastline, Climate, and Human Settlement. Springer, Dordrecht, pp. 489-514]
1.The Bàrenhòhle, one of the ten caves situated in the episodically water-bearing valley of the Lone (Swabian Jura), serves as summer quarters for the total of ten species of Trichoptera, most of which are Micropterna nycterobia and Stenophylax permistus. 2.Counts carried out in this cave from 1967-1972 and observations of flood and dry-periods of the Lone during the same years make evident that the number of Trichoptera flying into the cave seems to depend in a large measure on the seasonal activity of the creek: a steady flow of water makes the undisturbed development of larvae possible and results in high numbers of individuals entering by air, while intermittent water-flow disturbs the development of the larvae and results in few individuals entering. 3.Such factors as darkness, humidity, and temperature which cause or favour the active entrance by air of Trichoptera into the cave as well as the "diapause" taking place in the subterranean region are considered. 4.Dynamically climatized caves or caves which are too small are rarely occupied by Trichoptera; they evidently prefer larger caves with climatically balanced regions (comparatively low temperatures and high atmospheric moisture) not too far from the entrance. 5.Trichoptera start flying into the Barenhohle generally in May; the highest number of individuals and copulating couples may be found as early as July. They start flying out by the end of July or in August/September, the last of them leaving the cave generally in September or October. 6.Two attempts at marking (on 28th June all Trichoptera to be found in the cave were marked with black ink, on 4th July all yet unmarked with red ink) gave better evidence of their disposition and time of copulation as well as of the number of arriving unmarked and departing marked specimens. 7.The Trichoptera marked with black ink stayed in the cave for a maximum of 85 days, the ones marked with red ink for a maximum of 79 days. Food intake was not observed during this period, and there was no indication of the insects' leaving the cave during their diapause. 8.Trichoptera are characterized by a remarkably long time of copulation: a specimen marked twice was in copula for 22 days, and before copulation it had been in the cave for 49 days.
1.The Bàrenhòhle, one of the ten caves situated in the episodically water-bearing valley of the Lone (Swabian Jura), serves as summer quarters for the total of ten species of Trichoptera, most of which are Micropterna nycterobia and Stenophylax permistus. 2.Counts carried out in this cave from 1967-1972 and observations of flood and dry-periods of the Lone during the same years make evident that the number of Trichoptera flying into the cave seems to depend in a large measure on the seasonal activity of the creek: a steady flow of water makes the undisturbed development of larvae possible and results in high numbers of individuals entering by air, while intermittent water-flow disturbs the development of the larvae and results in few individuals entering. 3.Such factors as darkness, humidity, and temperature which cause or favour the active entrance by air of Trichoptera into the cave as well as the "diapause" taking place in the subterranean region are considered. 4.Dynamically climatized caves or caves which are too small are rarely occupied by Trichoptera; they evidently prefer larger caves with climatically balanced regions (comparatively low temperatures and high atmospheric moisture) not too far from the entrance. 5.Trichoptera start flying into the Barenhohle generally in May; the highest number of individuals and copulating couples may be found as early as July. They start flying out by the end of July or in August/September, the last of them leaving the cave generally in September or October. 6.Two attempts at marking (on 28th June all Trichoptera to be found in the cave were marked with black ink, on 4th July all yet unmarked with red ink) gave better evidence of their disposition and time of copulation as well as of the number of arriving unmarked and departing marked specimens. 7.The Trichoptera marked with black ink stayed in the cave for a maximum of 85 days, the ones marked with red ink for a maximum of 79 days. Food intake was not observed during this period, and there was no indication of the insects' leaving the cave during their diapause. 8.Trichoptera are characterized by a remarkably long time of copulation: a specimen marked twice was in copula for 22 days, and before copulation it had been in the cave for 49 days.
