Jacques Mudry - Academia.edu (original) (raw)
Papers by Jacques Mudry
HAL (Le Centre pour la Communication Scientifique Directe), Feb 19, 2014
Hydrogeology and water balance in karst terrain Jacques Mudry Chrono-Environnement, Besancon (Fra... more Hydrogeology and water balance in karst terrain Jacques Mudry Chrono-Environnement, Besancon (France) 1 Introduction Karst is defined as "all superficial and underground landforms produced by dissolution of specific rocks, mainly limestone". At the same time, it is a morphological structure (requiring thermodynamic and hydrodynamic conditions), a hydrosystem (input-box-output), and an aquifer (water resource, man impact, protection). Different academic specialties study karst: Physical Geography, Speleology, Geology, Hydraulics, Hydrogeochemistry, Pedology, and also engineering specialties: Geophysics, Hydrogeology, Geotechnics. Comprising external and internal landforms, karst is characterized by its internal draining pattern gathering water from up to downstream. This pattern originates in dissolution action on sedimentary and tectonic pre-existing discontinuities. This dissolution can be roughly synthetized by: CaCO3 + CO2 + H2O Ca2+ + HCO3- This equation requires CO2 providers, sometimes deep gas (thermal karst), but mainly soil in the most common case of meteoric karst. As carbonates outcrop under various climates, karst is therefore widely dispread in the world. The common feature of all these contexts is this flow structuration on the pattern of enlarged fractures. This structuration transforms a rather homogeneous media into a more or less heterogeneous one, depending on geological duration of the process. 2 karst heterogeneity We can observe three types of heterogeneities in karst: (i) a vertical heterogeneity with epikarst and vadose zone vs saturated zone; (ii) a spatial one with conduits (karstified fractures) vs microfissured blocks; (iii)a heterogeneity of inputs with karrenfields with diffuse infiltration vs swallow holes with concentrated infiltration. Behavior of karst is strongly influenced by this heterogeneity and anisotropy of karst systems. 3 hydrodynamic and hydrochemical consequences Due to the existence of a decompressed-open shallow zone called epikarst, infiltration process is more complicated than in a classic inter granular media. Water fills first this first reservoir which recharges, by means of tectonic vertical discontinuities, the saturated zone. Due to the existence of very permeable conduits and lowly permeable microfissured blocks, water exchanges occur between both media, conduits recharging blocks during flood episodes, and blocks supplying conduits during low-water periods. This heterogeneity of functioning induces a scale effect: the bigger the system, the more permeable it is, because big lumps of limestone include bigger fractures than small ones. Another consequence concerns residence time. In karst, contrary to more homogeneous aquifers, a contrast between long residence time waters (tenths or hundreds of years), stored in blocks, and shortest transits (hour to day) can be displayed. This way of behavior, added to the structure of the draining pattern enables existence of the big karst springs, with high flood discharges (sometimes >100 m3/s), but also with high depletion discharge (several m3/s). Existence of significant volumes (up to million m3/s), transiting the conduits induces 'piston-effect' which leads to yield 'pre-event' water at the beginning of floods. The consequence is a delayed mass transfer vs pressure transfer: water from the rainfall is not that flows at the spring at the discharge peak. Chemical composition of karst springs depends of the water transit through different media. The soil cover and the epikarst, submitted to evaporation, act as buffer for the hydrograph peak and marks water with characteristic tracers that are produced, stored or concentrated inside: e.g. chloride, provided by precipitations and concentrated by evaporation, and total organic carbon (TOC), produced by biological processes of pedogenesis. These tracers can be combined to the typical tracers of carbonate reservoir, e.g. magnesium and 13 C. As an example of transit time identification through vadose zone: the low-noise underground laboratory (LSBB, southeastern France) displays 1 month delay between rainfall and discharge peak in an artificial gallery, and 1 additional month for the infiltration itself to reach this point. Total: 2 months to pass vertically through 400 m of limestone. As an example of mixture identification in the saturated zone: the Fourbanne system (Jura mountains, Eastern France) displays well the behavior of the same water body, identified in a swallow hole by uranin tracing. This colored body is re-sampled within the conduit network, and finally in the general outlet of the system. As it is the same water, its chemical evolution will display mixtures with other components. The main results are that in the vadose conduit, the composition is similar to the input, and that the transit in the saturated zone involves a mixture with larger residence time water (making increase magnesium concentration), and poorer in agricultural tracers (making…
Landslides and Climate Change: Challenges and Solutions, 2007
The "Rochers de Valabres" is a fractured rock slope located in the French Alps and afec... more The "Rochers de Valabres" is a fractured rock slope located in the French Alps and afected by rockfall. This slope has been chosen as an experimental site for improving knowledge on mechanisms leading to rockfall. Since 2002 scientific investigations (field observations, monitoring and numerical modelling) have been carried out on the site. A seismic network has recorded a significant seismic activity correlated with existing discontinuities. Mechanical measurements using tiltmeters monitor the slope movements in order to improve the knowledge on thermo-hydromechanical process. Different geometrical and mechanical models have been performed. In 2005 the site was chosen to concentrate research on understanding the efffect of climate change on rock slope stability in the framework of a French national program named STABROCK. This paper presents teh results of field measurements and numerical modelling carried out on the experimental site and the complementary investigations will start within the new research. The aim is to study more accurately the impact of environmental factors on rock slope instability mechanisms and to assess the possible effect of the climate change. Technical results will be integrated in a process of risk management.
There is a large community of researchers in resource management in Africa, but they are currentl... more There is a large community of researchers in resource management in Africa, but they are currently partly disconnected, even in a single country. Most researchers engaged in the Lake Chad Basin are involved in studies motivated nationally or in their own institutions. Groundwater or streams do not stop at political borders. This means that investigation must also cross national borders. As a consequence and considering that no country or region is independent of the rest of the word, international research collaboration stands out as the major challenge in addressing excellence and sustainability of scientific activities in the future? A multi and interdisciplinary approach and international cooperation are absolutely essential for positive realization of the objectives of water resource management in the Lake Chad basin. In 2002 the UNESCO project “Virtual laboratories for drying lakes in Africa, Middle East and Central Asia” was a joint effort to mobilizing researchers of the sub ...
Desalination and Water Treatment, 2013
… Impacts of Climatic …, 2005
... As consequence of the decrease in groundwater levels, over 60% of wells and boreholes have ru... more ... As consequence of the decrease in groundwater levels, over 60% of wells and boreholes have run dry. ... and reverberate directly on the local population (fishers, farmers, breeders) and on the animal life in the Waza National Park. ... Les aquiferes du Grand Yae>£ (Nord Cameroun ...
HAL (Le Centre pour la Communication Scientifique Directe), Jan 20, 2021
International audienc
Dunod eBooks, 2016
L'hydrogeologie, science de l'eau souterraine, a pour objectif de planifier au mieux l... more L'hydrogeologie, science de l'eau souterraine, a pour objectif de planifier au mieux l'exploitation des ressources en eau. Elle doit donc identifier des aquiferes ou nappes d'eau souterraine, mais elle doit, surtout aujourd'hui, proteger et gerer les ressources en eau. Cet ouvrage est structure en quatre parties. La premiere presente le cycle de l'eau, les aquiferes souterrains et la circulation des eaux. la deuxieme decrit les outils et les methodes de l'hydrogeologie. La troisieme fait le point sur la ressource en eau a l'echelle de la planete. La quatrieme porte sur l'hydrogeologie et le genie civil (glissements de terrain, barrages, tunnels...)Cette nouvelle edition actualisee presente les dernieres techniques de modelisation en hydrogeologie et s'enrichit d'un lexique francais/anglais.
AGU Fall Meeting Abstracts, Dec 1, 2005
ABSTRACT An hydrogeochemical study was carried out in two glacial Alpine valleys which are the si... more ABSTRACT An hydrogeochemical study was carried out in two glacial Alpine valleys which are the site of numerous slope rock instabilities in gneissic rocks. Spatial variability of groundwater sulfate concentration in the two valleys, and a seven year long monitoring of groundwater chemistry of springs draining instable areas reveal the possibility to use hydrochemistry (mainly sulfate concentration in water) as a tool to identify current instable area. Hydro-chemistry evolves in time with the reaction kinetics of sulfate dissolution on pyriteous minerals. Significant residence time evolution or deep water mixing at the spring located in the instable area can not explain this evolution. Thus, during low-water periods, the dynamics of dissolution in the moving masses is modified, by water-rock interactions due to hydrological, mechanical and chemical processes. Leaching experiments of gneiss enable to identify the mechanisms of sulfate evolution linked with deformation. Scanning electron microscopy shows thin layers of ferrous oxides on weathered gneiss fractures, where the dissolution has occurred. The observed time evolution of sulfate concentration can be explained by neoformed minerals that limit the kinetics of dissolution. Thus the sulfate content variability in fractured rock slopes is a short term tools to discriminate current instable area.
HAL (Le Centre pour la Communication Scientifique Directe), 2006
International audienc
HAL (Le Centre pour la Communication Scientifique Directe), 2007
HAL (Le Centre pour la Communication Scientifique Directe), 2010
HAL (Le Centre pour la Communication Scientifique Directe), 2006
International audienc
HAL (Le Centre pour la Communication Scientifique Directe), Dec 16, 2021
HAL (Le Centre pour la Communication Scientifique Directe), Feb 19, 2014
Hydrogeology and water balance in karst terrain Jacques Mudry Chrono-Environnement, Besancon (Fra... more Hydrogeology and water balance in karst terrain Jacques Mudry Chrono-Environnement, Besancon (France) 1 Introduction Karst is defined as "all superficial and underground landforms produced by dissolution of specific rocks, mainly limestone". At the same time, it is a morphological structure (requiring thermodynamic and hydrodynamic conditions), a hydrosystem (input-box-output), and an aquifer (water resource, man impact, protection). Different academic specialties study karst: Physical Geography, Speleology, Geology, Hydraulics, Hydrogeochemistry, Pedology, and also engineering specialties: Geophysics, Hydrogeology, Geotechnics. Comprising external and internal landforms, karst is characterized by its internal draining pattern gathering water from up to downstream. This pattern originates in dissolution action on sedimentary and tectonic pre-existing discontinuities. This dissolution can be roughly synthetized by: CaCO3 + CO2 + H2O Ca2+ + HCO3- This equation requires CO2 providers, sometimes deep gas (thermal karst), but mainly soil in the most common case of meteoric karst. As carbonates outcrop under various climates, karst is therefore widely dispread in the world. The common feature of all these contexts is this flow structuration on the pattern of enlarged fractures. This structuration transforms a rather homogeneous media into a more or less heterogeneous one, depending on geological duration of the process. 2 karst heterogeneity We can observe three types of heterogeneities in karst: (i) a vertical heterogeneity with epikarst and vadose zone vs saturated zone; (ii) a spatial one with conduits (karstified fractures) vs microfissured blocks; (iii)a heterogeneity of inputs with karrenfields with diffuse infiltration vs swallow holes with concentrated infiltration. Behavior of karst is strongly influenced by this heterogeneity and anisotropy of karst systems. 3 hydrodynamic and hydrochemical consequences Due to the existence of a decompressed-open shallow zone called epikarst, infiltration process is more complicated than in a classic inter granular media. Water fills first this first reservoir which recharges, by means of tectonic vertical discontinuities, the saturated zone. Due to the existence of very permeable conduits and lowly permeable microfissured blocks, water exchanges occur between both media, conduits recharging blocks during flood episodes, and blocks supplying conduits during low-water periods. This heterogeneity of functioning induces a scale effect: the bigger the system, the more permeable it is, because big lumps of limestone include bigger fractures than small ones. Another consequence concerns residence time. In karst, contrary to more homogeneous aquifers, a contrast between long residence time waters (tenths or hundreds of years), stored in blocks, and shortest transits (hour to day) can be displayed. This way of behavior, added to the structure of the draining pattern enables existence of the big karst springs, with high flood discharges (sometimes >100 m3/s), but also with high depletion discharge (several m3/s). Existence of significant volumes (up to million m3/s), transiting the conduits induces 'piston-effect' which leads to yield 'pre-event' water at the beginning of floods. The consequence is a delayed mass transfer vs pressure transfer: water from the rainfall is not that flows at the spring at the discharge peak. Chemical composition of karst springs depends of the water transit through different media. The soil cover and the epikarst, submitted to evaporation, act as buffer for the hydrograph peak and marks water with characteristic tracers that are produced, stored or concentrated inside: e.g. chloride, provided by precipitations and concentrated by evaporation, and total organic carbon (TOC), produced by biological processes of pedogenesis. These tracers can be combined to the typical tracers of carbonate reservoir, e.g. magnesium and 13 C. As an example of transit time identification through vadose zone: the low-noise underground laboratory (LSBB, southeastern France) displays 1 month delay between rainfall and discharge peak in an artificial gallery, and 1 additional month for the infiltration itself to reach this point. Total: 2 months to pass vertically through 400 m of limestone. As an example of mixture identification in the saturated zone: the Fourbanne system (Jura mountains, Eastern France) displays well the behavior of the same water body, identified in a swallow hole by uranin tracing. This colored body is re-sampled within the conduit network, and finally in the general outlet of the system. As it is the same water, its chemical evolution will display mixtures with other components. The main results are that in the vadose conduit, the composition is similar to the input, and that the transit in the saturated zone involves a mixture with larger residence time water (making increase magnesium concentration), and poorer in agricultural tracers (making…
Landslides and Climate Change: Challenges and Solutions, 2007
The "Rochers de Valabres" is a fractured rock slope located in the French Alps and afec... more The "Rochers de Valabres" is a fractured rock slope located in the French Alps and afected by rockfall. This slope has been chosen as an experimental site for improving knowledge on mechanisms leading to rockfall. Since 2002 scientific investigations (field observations, monitoring and numerical modelling) have been carried out on the site. A seismic network has recorded a significant seismic activity correlated with existing discontinuities. Mechanical measurements using tiltmeters monitor the slope movements in order to improve the knowledge on thermo-hydromechanical process. Different geometrical and mechanical models have been performed. In 2005 the site was chosen to concentrate research on understanding the efffect of climate change on rock slope stability in the framework of a French national program named STABROCK. This paper presents teh results of field measurements and numerical modelling carried out on the experimental site and the complementary investigations will start within the new research. The aim is to study more accurately the impact of environmental factors on rock slope instability mechanisms and to assess the possible effect of the climate change. Technical results will be integrated in a process of risk management.
There is a large community of researchers in resource management in Africa, but they are currentl... more There is a large community of researchers in resource management in Africa, but they are currently partly disconnected, even in a single country. Most researchers engaged in the Lake Chad Basin are involved in studies motivated nationally or in their own institutions. Groundwater or streams do not stop at political borders. This means that investigation must also cross national borders. As a consequence and considering that no country or region is independent of the rest of the word, international research collaboration stands out as the major challenge in addressing excellence and sustainability of scientific activities in the future? A multi and interdisciplinary approach and international cooperation are absolutely essential for positive realization of the objectives of water resource management in the Lake Chad basin. In 2002 the UNESCO project “Virtual laboratories for drying lakes in Africa, Middle East and Central Asia” was a joint effort to mobilizing researchers of the sub ...
Desalination and Water Treatment, 2013
… Impacts of Climatic …, 2005
... As consequence of the decrease in groundwater levels, over 60% of wells and boreholes have ru... more ... As consequence of the decrease in groundwater levels, over 60% of wells and boreholes have run dry. ... and reverberate directly on the local population (fishers, farmers, breeders) and on the animal life in the Waza National Park. ... Les aquiferes du Grand Yae>£ (Nord Cameroun ...
HAL (Le Centre pour la Communication Scientifique Directe), Jan 20, 2021
International audienc
Dunod eBooks, 2016
L'hydrogeologie, science de l'eau souterraine, a pour objectif de planifier au mieux l... more L'hydrogeologie, science de l'eau souterraine, a pour objectif de planifier au mieux l'exploitation des ressources en eau. Elle doit donc identifier des aquiferes ou nappes d'eau souterraine, mais elle doit, surtout aujourd'hui, proteger et gerer les ressources en eau. Cet ouvrage est structure en quatre parties. La premiere presente le cycle de l'eau, les aquiferes souterrains et la circulation des eaux. la deuxieme decrit les outils et les methodes de l'hydrogeologie. La troisieme fait le point sur la ressource en eau a l'echelle de la planete. La quatrieme porte sur l'hydrogeologie et le genie civil (glissements de terrain, barrages, tunnels...)Cette nouvelle edition actualisee presente les dernieres techniques de modelisation en hydrogeologie et s'enrichit d'un lexique francais/anglais.
AGU Fall Meeting Abstracts, Dec 1, 2005
ABSTRACT An hydrogeochemical study was carried out in two glacial Alpine valleys which are the si... more ABSTRACT An hydrogeochemical study was carried out in two glacial Alpine valleys which are the site of numerous slope rock instabilities in gneissic rocks. Spatial variability of groundwater sulfate concentration in the two valleys, and a seven year long monitoring of groundwater chemistry of springs draining instable areas reveal the possibility to use hydrochemistry (mainly sulfate concentration in water) as a tool to identify current instable area. Hydro-chemistry evolves in time with the reaction kinetics of sulfate dissolution on pyriteous minerals. Significant residence time evolution or deep water mixing at the spring located in the instable area can not explain this evolution. Thus, during low-water periods, the dynamics of dissolution in the moving masses is modified, by water-rock interactions due to hydrological, mechanical and chemical processes. Leaching experiments of gneiss enable to identify the mechanisms of sulfate evolution linked with deformation. Scanning electron microscopy shows thin layers of ferrous oxides on weathered gneiss fractures, where the dissolution has occurred. The observed time evolution of sulfate concentration can be explained by neoformed minerals that limit the kinetics of dissolution. Thus the sulfate content variability in fractured rock slopes is a short term tools to discriminate current instable area.
HAL (Le Centre pour la Communication Scientifique Directe), 2006
International audienc
HAL (Le Centre pour la Communication Scientifique Directe), 2007
HAL (Le Centre pour la Communication Scientifique Directe), 2010
HAL (Le Centre pour la Communication Scientifique Directe), 2006
International audienc
HAL (Le Centre pour la Communication Scientifique Directe), Dec 16, 2021