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 estonian limnic territories, a baltic originality?

Place of presence of the main European lakes by their surface, the Baltic limnic area cannot be summed up with its tens of lakes of continental extent because it shelters tens of thousands of lakes morainic, thermokarstic and other artificial water bodies. Through limnosystemic and limnoregional approaches, temporal, spatial and anthroposystemic dimensions, the author endeavors to frame the 5 articles present in this thematic sub-part and questions the Estonian limnic territories through the prism of their limnic footprint index

Estonia’s water bodies, between originalities and limits to qualify its limnic territories

The five contributions presented in this issue provided an overview of the types of contemporary research in limnology, but they were not in any way intended to make it a comprehensive state. However, they have highlighted a number of environmental dynamics of this other “lake Country” to use J. Terasmaa’s expression and we will focus on putting them in perspective to answer questions posed when this part was introduced. To do this, we will show the double originality of the Estonian limnic t..

L’apport du cadastre napoléonien aux problématiques spatiales des retenues d’eau

Sous l’effet de mesures règlementaires françaises et européennes, les espaces hydrologiques sont aujourd’hui au devant de l’actualité scientifique et nombre de recherches voient le jour un peu partout. En tant que zones humides, les retenues d’eau font parties de ces objets géographiques à comprendre, d’autant plus qu’elles se situent de manière générale en tête de bassin et influent donc sur la qualité et la quantité de l’eau en aval. Grâce à l’utilisation de documents scientifiques anciens, il est possible de donner une dimension temporelle à l’étude de ces plans d’eau, et non seulement spatiale ou fonctionnelle. En cela, l’étude du cadastre napoléonien, élaboré de 1807 à 1850, offre la possibilité de comparer spatialement des territoires, de comprendre des dynamiques locales ou régionales, mais aussi de tenir compte des valorisations humaines. Appliquées aux trois départements de la Creuse, de l’Indre et de la Haute-Vienne, l’analyse du cadastre et la comparaison avec des inventaires actuels permettent d’affiner les méthodes d’utilisation de cet outil et d’élargir les champs d’investigation à d’autres disciplines scientifiques que la géographie.Concerned by French and European legal measures, hydrologic spaces are today at the forefront of scientific attention, and numerous researches are conducted here and there. As humid zones, reservoirs constitute a part of these geographical objects worth understanding, all the more so as they are generally situated upstream in a basin, and have an impact on the quality and volume of water downstream. The use of historical scientific documents allows to give a temporal, and not only spatial or functional dimension to the study of these reservoirs. To this effect, the study of the Napoleonic cadastre, realized between 1807 and 1850, offers the opportunity to compare territories spatially, to understand local or regional dynamics, but also to take into account man-made developments. Applied to the three departments of Creuse, Indre and Haute-Vienne, the cadastre analysis, and the comparison with present-day inventories allow to refine the methods available to analyse this tool, and to open up research to other scientific fields than geography

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

Les territoires limniques estoniens : une originalité baltique ?

Lieu de présence des principaux lacs européens par leur superficie, l’espace limnique baltique ne peut pour autant pas se résumer à ses dizaines de lacs d’ampleur continentale car il abrite des dizaines de milliers de lacs morainiques, thermokarstiques et autres plans d’eau artificiels. Au travers d’approches limnosystémiques et limnorégionales, des dimensions temporelles, spatiales et anthroposystémiques, l’auteur s’attache à cadrer les 5 articles présents dans cette sous-partie thématique et questionne les territoires limniques estoniens au prisme de leurs indicateurs d’empreinte limnique

Introduction. Du glint baltique au lac Peïpous

Pour des géographes, évoquer en 2018 l’Estonie, ce petit pays balte situé au nord-est de la mer Baltique, c’est mettre en avant sa géographie économique. Indépendante depuis 1991, l’Estonie est devenue le premier ex-Etat soviétique membre de la zone euro en 2002. Ce pays est ouvert aux innovations comme le vote électronique et constitue une opportunité économique pour ses voisins Norden, notamment la Finlande. C’est aussi parler géopolitique avec toutes les problématiques générées par la prés..

Introduction. From Baltic Glint to Lake Peipsi

For geographers, to evoke in 2018 Estonia, this small Baltic country located in the northeast of the Baltic Sea, is to highlight its economic geography. Independent since 1991, Estonia became a member of eurozone in 2002 as the first ex-Soviet state. This country is open to innovations such as electronic voting and is an economic opportunity for its Norden neighbours, particularly Finland. It is also to evoke geopolitic with all the problems generated by the presence of the Russian neighbour ..

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

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