Quentin Choffel | Université d'Orléans (Loire Valley University) (original) (raw)

Papers by Quentin Choffel

Dynamiques environnementales, 2018

The Kurtna Lake District, situated in the northeastern part of Estonia, contains the largest numb... more The Kurtna Lake District, situated in the northeastern part of Estonia, contains the largest number of lakes per km2 in the country-38 natural lakes in a 30 km 2 area. The unique area fell under severe anthropogenic influence in the middle of the 20 th century and the influence has continued until the present day. Oil-shale, sand and peat mining, groundwater and surface water abstraction-all have been affecting the lakes in the district. Lake water levels have dropped, lake chemistries and consequently lake ecosystems have changed. For some lakes the effects have been larger, but some lakes have remained mostly unchanged. In 1987 a landscape protection area was formed, but that has not solved the problems. The lake district used to contain five rare clear water lakes with low nutrient and mineral content (L. Valgejärv, L. Liivjärv, L. Ahnejärv, L. Martiska, L. Kuradijärv). Nowadays, most of them have become significantly more eutrophic, because of water level decrease, but L. Valgejärv, with its preserved unique plant communities, is still considered to be one of the ecologically most valuable lakes in Version française p. 208 Estonia. The lake district also contains the only siderotrophic (iron rich) lake in Estonia-Lake Räätsma. Lakes Nõmmejärv and Konsu have had their water regime changed considerably. Lake Nõmmejärv accepts the inflow of sulphate-rich mine water and Lake Konsu has been turned into a surface water reservoir for an oil-shale processing factory. Lake Kihljärv on the other hand has effectively dried out in the recent years. At the same time, the picturesque Lake Saarejärv has remained largely unaffected. Therefore, the Kurtna Lake District is an area of great contrasts, partly it still resembles the pristine nature it used to be, and partly it is a sad monument for an overly eager consumption of natural resources.

The majority of terrestrial standing water bodies (SWB) are small in size, however, their abundan... more The majority of terrestrial standing water bodies (SWB) are small in size, however, their abundance and distribution is not fully known and they are under-represented in legislation. Also, the models for global inventories of SWB are so far not sufficiently designed for estimating the relative abundance of small SWB (below 0.2 ha) and provide differing estimates. In this pilot study, we suggest a bottom-up approach for estimating the number of SWB at EU-level that combines the ground-validated data on water bodies from state inventories and data from peer-generated map databases; we assess the inventories and relative importance of small terrestrial water bodies of two different countries, Estonia and France.

DIE ERDE – Journal of the Geographical Society of Berlin, 2015

Annales de géographie, 2020

Malgre la rarete des etudes reposant sur des methodologies scientifiques rigoureuses pour estimer... more Malgre la rarete des etudes reposant sur des methodologies scientifiques rigoureuses pour estimer la quantite d’eau perdue des etangs francais via l’evaporation, les autorites les considerent comme une cause majeure de l’etiage estival du chevelu hydrographique de tete de bassin. L’evaporation des etangs enregistre ses taux les plus eleves en ete, mais les etudes anterieures avaient neglige la quantite d’eau pouvant etre perdue par l’evapotranspiration des plantes qui remplaceraient ces etangs s’ils etaient effaces. Dans cette recherche nous adaptons une approche basee sur l’eventuelle surevaporation qui se produit en depassement de l’evapotranspiration du terrain qui a existe ou existera en lieu et place de la nappe d’eau libre. Des mesures directes de l’evaporation d’un etang et de l’evapotranspiration des plantes occupant le fond d’un ancien etang rompu ont ete prises entre le 1er mars et le 30 septembre 2018 en Limousin. Les resultats montrent que la prairie humide a perdu 1,37 fois la quantite d’eau perdue par l’etang voisin. Concernant l’evapotranspiration, la comparaison entre les calculs des formules mathematiques et les mesures prises in situ montrent que la methode de Penman-Monteith ne prend pas en consideration le stade vegetatif des plantes. Concernant l’evaporation, la formule « Aldomany » donne des valeurs proches des mesures realisees sur l’etang, l’ecart moyen n’etant que de 6,4 %. Les methodes mathematiques utilisees dans cette recherche peuvent fournir des estimations acceptables de l’evapotranspiration reelle des prairies humides si le coefficient cultural calcule dans cette etude (1,37) est pris en consideration.

Heliyon, 2019

The abundance and properties of small standing water bodies (SSWB) is globally not well known for... more The abundance and properties of small standing water bodies (SSWB) is globally not well known for their ecological importance is undervalued and their detection suffers from technical limitations. In the current study, we used a combination of GIS-based methods (satellite, orthophoto, ground validation) to evaluate regional estimates of standing water body (SWB) inventories in two geographically different parts of Europe-France, and Estonia. In our study the SWBs surface area threshold limit was 0.00001 km 2 , exceeding the limits of previous studies (>0.002 km 2). The total number of SWBs in Estonia is 111 552 (2.5 per km 2) and in France 598 371 (1.1 per km 2). Our estimates show that the median size of SWBs in Estonia and France is 0.0003 km 2 and 0.0007 km 2 respectively, meaning that most of the SSWBs are not included in the global inventories, and their number is therefore underestimated. SSWBs (area below 0.01 km 2) form a significant share of the total shoreline length of SWBs, 70.3% in Estonia and 58.8% in France. As nearshore areas are often very productive with diverse habitats, the SSWBs hold a crucial role in maintaining biodiversity. Our results provide quantitative evidence that SSWBs are vital and abundant landscape elements, freshwater resources, and habitats that should not be ignored in global inventories.

Applied Science and Innovative Research, 2017

Despite many scientific papers published around the world on the evaporation of water bodies, few... more 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.

Geographia Technica, 2017

Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100... more Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100 ha. In the Limousine region (France), they usually bar small incised valleys, giving them a complex morphology. This morphology may separate the pond in several basins, as for the pond of La Ramade (45°47'04.3"N; 2°25'30.7''E), theoretically suitable for a spatial variation of temperature. The pond has been implemented with 4 moorings chains composed of automatic thermistors, measuring the temperature every hour from the surface to the bottom. A meteorological station has been deployed close to the pond, in order to gather very precise meteorological information, in addition to the map of fetch and bathymetry. The working hypothesis is that even small waterbodies present a spatial heterogeneity of water temperature, so that the classic measurements only at one point give approximate values. The aim is to get a 3D overview of the thermal dynamic of a small waterbody for the purpose of a better understanding of its temperature dynamic, with heat content's approach. In polymictic waterbody, the temporal but as well spatial variations of the heat content are together numerous and varied. The first results bring us the autonomous function of the bays and sheltering places, while the open water has a predictable function. Some parameters such as the fetch, the sheltering by vegetation or the bathymetry plays a more or less important role in the particularity of each basin. The heat content's methodology shall be improved by consideration of the spatial variation of the pond's temperature.

Dynamiques environnementales, 2018

A l'époque de la limnologie naissante, le lac Tchoudsk était tout entier compris dans l'Empire ru... more 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.

Despite the rarity of serious studies based on solid scientific methodologies to estimate the qua... more Despite the rarity of serious studies based on solid scientific methodologies to estimate the quantity of water lost from French ponds by evaporation, the French authorities consider these water bodies as the main cause of water loss and therefore the summer low water levels of the hydrographic networks. Certainly, pond evaporation records its highest rates in summer, but previous studies had neglected the amount of water that can be lost through plant evapotranspiration that would replace the ponds if they were dried up. In this research the Authors adapt an approach based on possible over-evaporation that occurs in excess of the wetland evapotranspiration that existed or would exist in place of the ponds. Direct measurements of pond evaporation and the evapotranspiration of plants occupying the bottom of an old broken-up pond were taken during the warm semester of 2018 in Limousin (France). The results of this research show that the wetland has lost 1.37 times the amount of water ...

Dynamiques environnementales

Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100... more Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100 ha. In the Limousine region (France), they usually bar small incised valleys, giving them a complex morphology. This morphology may separate the pond in several basins, as for the pond of La Ramade (45°47'04.3 " N; 2°25'30.7''E), theoretically suitable for a spatial variation of temperature. The pond has been implemented with 4 moorings chains composed of automatic thermistors, measuring the temperature every hour from the surface to the bottom. A meteorological station has been deployed close to the pond, in order to gather very precise meteorological information, in addition to the map of fetch and bathymetry. The working hypothesis is that even small waterbodies present a spatial heterogeneity of water temperature, so that the classic measurements only at one point give approximate values. The aim is to get a 3D overview of the thermal dynamic of a small waterbody for the purpose of a better understanding of its temperature dynamic, with heat content's approach. In polymictic waterbody, the temporal but as well spatial variations of the heat content are together numerous and varied. The first results bring us the autonomous function of the bays and sheltering places, while the open water has a predictable function. Some parameters such as the fetch, the sheltering by vegetation or the bathymetry plays a more or less important role in the particularity of each basin. The heat content's methodology shall be improved by consideration of the spatial variation of the pond's temperature.

Having reliable estimates of the number of water bodies on different geographical scales is of gr... more Having reliable estimates of the number of water bodies on different geographical scales is of great importance to better understand biogeochemical cycles and to tackle the social issues related to the economic and cultural use of water bodies. However, limnological research suffers from a lack of reliable inventories; the available scientific references are predominately based on water bodies of natural origin, large in size and preferentially located in previously glaciated areas. Artificial, small and randomly distributed water bodies, especially ponds, are usually not inventoried. Following Wetzel’s theory (1990), some authors included them in global inventories by using remote sensing or mathematical extrapolation, but fieldwork on the ground has been done on a very limited amount of territory. These studies have resulted in an explosive increase in the estimated number of water bodies, going from 8.44 million lakes (Meybeck 1995) to 3.5 billion water bodies (Downing 2010). These numbers raise several questions, especially about the methodology used for counting small-sized water bodies and the methodological treatment of spatial variables. In this study, we use inventories of water bodies for Sweden, Finland, Estonia and France to show incoherencies generated by the “global to local” approach. We demonstrate that one universal relationship does not suffice for generating the regional or global inventories of water bodies because local conditions vary greatly from one region to another and cannot be offset adequately by each other. The current paradigm for global estimates of water bodies in limnology, which is based on one representative model applied to different territories, does not produce sufficiently exact global inventories. The step-wise progression from the local to the global scale requires the development of many regional equations based on fieldwork; a specific equation that adequately reflects the actual relationship between distribution and abundance of water bodies in a given area must be produced for each geographical region.

Until recently, the small water bodies have been disregarded in the environmental management and ... more Until recently, the small water bodies have been disregarded in the environmental management and protection policies. For example, the European Water Framework Directive 2000/60/EC proposes the threshold surface area of water bodies for typology and reporting as 50 ha. The inventories on state level or scientific studies took into account smaller water bodies (e.g. <10 ha for Meybeck, 1995, <1 ha for Rjanžin, 2005, or <0.05 ha for Kuusisto and Raatikainen, 1988) but these methods of estimations has been region-specific and not suitable for global estimates. The increasing awareness about the important roles that terrestrial standing water bodies play in the biodiversity or hydrological and biogeochemical cycles has facilitated new global and regional inventories of lakes and water bodies. Although with differences in the total counts and in the statistical estimates of abundance-size relationship, these recent global estimates reveal the quantitative importance of the terrestrial standing water bodies in the global hydrology (Downing et al., 2006; Verpoorter et al., 2014). Yet, our analysis of the abundance and distribution EU water bodies suggest that these global counts underrepresents the hydrologically complex terrain of the European territory. One of the main limits is the high cutoff limit that excludes small water bodies below ~0.2 ha. For example, in France, Bartout and Touchart (2013) report that including water bodies below 0.01 ha in the estimates resulted in 16 times higher number of water bodies with the surface area one-third higher than officially registered inventories. Also, in Estonia, the water bodies with a surface area below 1 ha are almost 50 times more abundant than those above 1 ha and 92% of all standing water bodies are smaller than 0.2 ha. Using the OpenStreetMap database we will discuss the differences between global inventories and EU-level analysis. We will show the alternative regional estimates of water bodies with the surface size threshold limit 0.01 ha which will illustrate the quantitative importance of very small often man-made ponds, which are however, abundant cultural heritage in many parts of Europe. Secondly, by comparing detailed national inventories compiled for France and Estonia, we will introduce usefulness of the the 'local to global' approach in which the local databases may significantly strengthen the precision of the regional (EU) level analysis. Overall, we will discuss that all standing water bodies – including small and man-made ponds – play an important role in ecosystem services and require careful management to avoid hydrological and environmental deterioration.

Dynamiques environnementales, 2018

DIE ERDE – Journal of the Geographical Society of Berlin, 2015

Annales de géographie, 2020

Heliyon, 2019

Applied Science and Innovative Research, 2017

Geographia Technica, 2017

Dynamiques environnementales, 2018

Dynamiques environnementales

Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100... more Ponds are regarded as small waterbodies with a depth of less than 6m and an area of less than 100 ha. In the Limousine region (France), they usually bar small incised valleys, giving them a complex morphology. This morphology may separate the pond in several basins, as for the pond of La Ramade (45°47'04.3 " N; 2°25'30.7''E), theoretically suitable for a spatial variation of temperature. The pond has been implemented with 4 moorings chains composed of automatic thermistors, measuring the temperature every hour from the surface to the bottom. A meteorological station has been deployed close to the pond, in order to gather very precise meteorological information, in addition to the map of fetch and bathymetry. The working hypothesis is that even small waterbodies present a spatial heterogeneity of water temperature, so that the classic measurements only at one point give approximate values. The aim is to get a 3D overview of the thermal dynamic of a small waterbody for the purpose of a better understanding of its temperature dynamic, with heat content's approach. In polymictic waterbody, the temporal but as well spatial variations of the heat content are together numerous and varied. The first results bring us the autonomous function of the bays and sheltering places, while the open water has a predictable function. Some parameters such as the fetch, the sheltering by vegetation or the bathymetry plays a more or less important role in the particularity of each basin. The heat content's methodology shall be improved by consideration of the spatial variation of the pond's temperature.