THE INFLUENCE OF MONK EQUIPPED PONDS ON THE QUALITY OF BASIN HEAD STREAMS, THE EXAMPLE OF WATER TEMPERATURE IN LIMOUSIN AND BERRY (FRANCE)

In the centre-west regions of France, the deep water outlet system known as a “monk” is used in 13% of bodies of water. The authorities are strongly encouraging this to increase, arguing that this system would reduce pond induced warming of the hydrographical network. We have measured the water temperature in four monk equipped ponds for 13 years to such an extent that this paper draws on an analysis of 142,200 original measurements. Compared to a surface outflow, a monk is a system which shifts the warming of the emissary water course to the end of summer and the autumn which reduces average annual warming by about 1°C. This reduces the heating of diurnal maxima but increases warming of the minima. A monk equipped pond warms the river with deep water which has acquired its heat by mechanical convection generated by the wind, as opposed to a weir equipped pond which provides surface water warmed by insolation. In winter the monk equipped pond does not damage the thermal living conditions for Fario trout embryos and larvae under the gravel. In summer, the monk prevents night time cooling of the emissary and increases the temperature of the minima excessively for sensitive species

THE INFLUENCE OF PONDS ON DISSOLVED OXYGEN IN SMALL RIVERS OF BERRY (FRANCE)

The influence of ponds on dissolved oxygen in small rivers of Berry (France). Water temperature and oxygen saturation are two major indicators of water quality in surface hydrology. Geographical and cartographic studies about ponds of Central France did no exist until now. During two years, we measured dissolved oxygen using a hand oximeter upstream and downstream of three ponds in the headwaters of the Loire basin. Our results show that oxygen saturation depends on equipments located before and behind the dam, and upstream and downstream: spillways, outlets with a monk, diversion channel, artificial reoxygenation weirs and so on. In some cases (low water quality upstream, existence of weir), relative and absolute saturation of dissolved oxygen increases downstream of ponds

Typologie des lacs polaires

Le critère typologique de l’isolement dû à la glace est majeur et son importance est replacée en fonction de la régularité interannuelle du taux de la couverture glaciaire ou glacielle. La barrière la plus hermétique est celle d’un glacier continental, suivie par celle d’une banquise lacustre permanente. Chez les lacs à couverture glacielle saisonnière, les plans d’eau superficiels, que le gel est susceptible de faire disparaître chaque année, ont une chaîne trophique beaucoup plus pauvre que les grands lacs profonds, capables de fournir des conditions favorables à la vie malgré l’ampleur du marnage.The major typological criterion for classifying polar lakes is the isolation by the ice cover. The significance of this phenomenon depends on the inter-annual regularity of the ice regime. Continental glaciers are the main obstacle between water and atmosphere; perennially frozen lakes are largely isolated too. The seasonally frozen lakes are either shallow and deep lakes. Polar ponds and shallow lakes, which may completely freeze and disappear each year, are biologically poor, whereas deep polar lakes present a complete trophic cycle despite the great water level fluctuations

Direct Measurements and New Mathematical Methods to Estimate the Pond Evaporation of the French Midwest

Despite many scientific papers published around the world on the evaporation of water bodies, few detailed evaporation studies exist for ponds, especially the ponds of humid areas like the French Midwest. Two full years of daily evaporation measurements on two different types of ponds were carried out using a transparent floating evaporation pan. A comparison between a class A evaporation pan and the transparent floating evaporation pan shows that the latter has almost no influence on the water temperature. As a consequence, the measurements taken by this evaporation pan were used to evaluate the reliability of 18 different mathematical methods. These mathematical methods use climate data provided by a weather station installed at the edge of the studied ponds to calculate evaporation. The comparison between measured and calculated evaporation shows that the new empirical formula of Aldomany is the best formula that we can use to estimate the ponds evaporation

La répartition des populations piscicoles en Creuse (Limousin), l’apport géographique des pêches électriques en tête de bassin

Le département de la Creuse a une situation hydrologique de tête de bassin, que le bon état écologique des cours d’eau permet de considérer comme un espace de référence. Les pêches électriques sont utilisées de manière géographique pour cartographier la répartition des poissons représentatifs d’une certaine qualité des eaux et leur suivi pendant sept ans sur un vaste espace de 5 600km². D’année en année, les espèces peu exigeantes (chevesne et vandoise) progressent de l’aval vers l’amont, tandis que les espèces les plus exigeantes (vairon) régressent pour ne plus subsister qu’en tête de bassin. Ces espèces sont les traceurs d’une dégradation des conditions physico-chimiques ou sédimentaires remontant d’aval en amont.The department of the Creuse is located in the highlands of the French Central Massif, where the headwater catchments constitute a reference area for the ecologically healthy small watercourses. Electrofishing is used here in a geographical way in order to chart the repartition of fish species representative of a certain water quality, covering a period of seven years and a large area of 5 600 km². Over the years, populations of the least sensitive species (chub and dace) progress towards upstream waters, while the most sensitive species (minnows) regress and only subsist in the headwaters. These species are indicators of a degradation of physicochemical or sedimentary conditions moving upstream

The evaporation from ponds in the French Midwest

This research shows the results of a study about evaporation in five ponds in the Midwest of France. To realize this study we used climate data from the meteorological station of the Limoges-Bellegarde airport and the data of a weather station installed by us near one of the ponds. We used eight different methods to calculate the evaporation rate and we modified the Penman-Monteith method by replacing the air temperature by water temperature. To understand the role of ponds in water loss through evaporation, we proposed a hypothesis that says : if the pond did not exist, what results would we get? Based on this hypothesis we calculated the potential evapotranspiration rate taking into account the percentage of interception by vegetation. In conclusion, this study indicates that the ponds in the French Midwest present a gain of wate

Dynamic Limnology Between Actors and Managements.

The subject proposed in this article concerns the intersection of the hydrodynamics of lakes and ponds with the economic development of their territory. It will be a question of understanding the interactions between these water bodies and territorial actors evolving on these limnic territories. Different managements are therefore imposed on each of the parties present. These managements are organized according to the limnological mechanisms specific to each environment (ponds and lakes), their temporality, their spatiality, and their risks for the human activities integrated into these water bodies. We will focus in this article on water and sediment movements not yet studied to interact with local managements. These phenomena constitute a base on which the actors around these water bodies can rely to guide the measures used to protect their activities. The purpose of this article is to provide scientific insights for decision support to actors evolving in the federation of municipalities of the Great Lakes, in the Landes, in New-Aquitaine (France)

Le lac Tchoudsk (Peïpous) et les recherches limnologiques à l’époque de la Russie impériale

A l’époque de la limnologie naissante, le lac Tchoudsk était tout entier compris dans l’Empire russe. Les premières recherches répondirent au besoin de mieux connaître et préserver les ressources halieutiques et ce fut Karl von Baer qui lança ces études dans les années 1850. Ces mêmes années virent des recherches sur l’ensemble du lac et de son émissaire fluvial, la Narva, dans le but de canaliser celle-ci tout en abaissant le niveau du lac, puis de profiter de son potentiel énergétique. Dès les années 1860, le géologue Gregor von Helmersen rédigea la première monographie complète du lac Tchoudsk, mais il fallut attendre la campagne de 1895 menée par le géographe Joseph Spindler pour obtenir la première carte bathymétrique du lac et le tracé des isothermes de la température de l’eau à toutes les profondeurs. Avant l’indépendance de l’Estonie issue de la Première Guerre Mondiale, la plupart des limnologues travaillant sur les lacs Tchoudsk et Pskov étaient des savants germano-baltes de citoyenneté russe mettant à profit la rencontre de plusieurs cultures scientifiques

Lake Chudsk (Peipus) and limnological research in Imperial Russia

At the beginning of limnology, Lake Chudsk was entirely included in the Russian Empire. The first research answered the need to better understand and preserve fishery resources. Karl von Baer initiated the project in the 1850s. In the same years, research was carried out on the entire lake and its outfall, the Narva, in order to channel its energy while lowering the lake water level and then take advantage of its energetic potential. In the 1860s, the geologist Gregor von Helmersen wrote the first complete monograph of Lake Chudsk, but it was not until the 1895 campaign led by the geographer Joseph Spindler that the first bathymetric map of the lake was produced and the isothermal pattern of the temperature at all depths were plotted. Before Estonia became independent at the end of the First World War, most of the limnologists working on Lakes Chudsk and Pskov were German-Baltic scientists of Russian citizenship, favoring the encounter of several scientific cultures

Vladimir Obroutchev, le Jules Verne russe qui fut vraiment explorateur

Les découvertes, les expéditions scientifiques et les voyages de science-fiction de V.A. Obroutchev (1863-1956) sont étudiés à partir du dépouillement des archives de l’Académie des sciences de Russie, d’entretiens inédits avec des spécialistes de l’édition et avec des chercheurs utilisant encore ses travaux, ainsi que de visites de terrain recoupant les itinéraires qu’il avait suivis il y a un siècle. Géologue de formation, mais très lié à la Société de géographie, son principal héritage scientifique concerne l’effet de la néotectonique faillée dans le rajeunissement des massifs anciens, l’importance des remaniements postérieurs aux dépôts des lœss et la nature des gisements aurifères alluvionnaires cimentés par le pergélisol. Passionné par le terrain et les explorations lointaines, Obroutchev en a effectué de multiples en Sibérie et en Asie centrale russe, mais ce fut sa participation à la seconde expédition de Potanine en Chine qui le rendit célèbre. La renommée d’Obroutchev dépassa la sphère scientifique pour atteindre au monde culturel, grâce à ses deux romans, traduits dans le monde entier, qui firent de lui l’inventeur de la science-fiction russe. Ce sont de grands voyages initiatiques et imaginaires, devant beaucoup à la géographie, surtout la Terre de Sannikov, et à la géologie, en particulier la Plutonie. Dans le premier, l’île forme un isolat géographique autorisant la préservation de la paléogéographie de la dernière glaciation. Dans le second, la zonation géographique fait se succéder les périodes géologiques : plus on va vers le sud, plus on remonte dans le temps.Discoveries, scientific expeditions and science fiction trips of V.A. Obruchev (1863-1956) are studied considering the examination of the archives of the Russian Academy of Sciences, unpublished interviews with specialists and with researchers still using his work, as well as field visits along the itineraries he had followed a century ago. Trained as geologist, closely associated with the Society of Geography, his main scientific heritage concerns the impact of fault neotectonics in the rejuvenation of the old mountains, the importance of reworked lœss in Asia and the conditions of gold diggings in permafrost. Passionate about field work and distant expeditions, he explored many parts of Siberia and Central Asia; his participation in the second Potanin’s expedition in China made him famous. Obruchev’s reputation went beyond the scientific sphere to reach the cultural world, thanks to his two novels, translated all over the world, which made him the inventor of Russian science fiction. These great initiatory and imaginary journeys owe much to geography, especially Sannikov land, and to geology, especially Plutonia. In the first, the island forms a geographical isolate allowing the preservation of the paleogeography of the last glaciation. In the second, the geographical zonation follows the geological periods: the more we go south, the more we go back in time