Dr. Adrien Guyot

Dr. Adrien Guyot

Research Fellow
Department of Civil Engineering
Room 231, 21 Alliance Lane, Clayton Campus

Dr Adrien Guyot is a Research Fellow at Monash University. Prior to joining Monash University (in 2017), he worked at The University of Queensland (2010-2017) just after obtaining his PhD from the University of Grenoble in France. He is currently Honorary Fellow at The University of Queensland. He was course coordinator of the Monash University Master course unit CIV5883 & 6883 in 2018 and is currently lecturing the classes on physical processes of that course.

He is working with advanced sensing instruments to monitor the earth system within the critical zone and the atmospheric boundary layer. His research help to build a better understanding of the environmental systems, and engineer tools to support land and water management, weather and climate forecasting, wildfire mitigation and flood prediction in both natural and urbanised environments.

Qualifications

  • Ph.D Hydrology and Atmospheric Sciences, Université Joseph Fourier (Grenoble I).
  • MSc. Hydrology and Atmospheric Sciences, Université Joseph Fourier (Grenoble I)
  • Magistère Earth Sciences (TAO), Ecole Normale Supérieure, Paris.
  • Honours Physics, Université Blaise Pascal (Clermont-II) - Clermont-Ferrand.

Expertise

Environmental Engineering
Water resources
Wildfires
Eco-Hydrology

Research Experience and Employment History:

2017 – Present   Research Fellow & Course Coordinator, Department of Civil Engineering, Monash University

2017 – Present   Honorary Research Fellow, The University of Queensland

2014 – 2017   UQ Research Fellow, School of Civil Engineering, The University of Queensland

2010 – 2014   Research Fellow, School of Civil Engineering, The University of Queensland

Honors & Awards:

2014 – 2016   UQ Postdoctorate Fellowship Award.

2013   NCGRT Research Award for Excellence in science and research.

2007 – 2010   CNRS BDI Fellowship Award.

Research Interests

Dr Adrien Guyot has an initial formation in physics and started his research career during his PhD working on land-atmosphere interactions in the context of the West African Monsoon. Since then, he has been committed to work on developing a better understanding of processes within the critical zone and the atmospheric boundary layer to help provide decision makers with tools to manage and mitigate the impact of global changes and climate extremes.

Research Projects

Current projects

Improved Rainfall Measurement Using Mobile Phone Tower Link Attenuation

Accurate near-real-time precipitation data at high resolution are critical to flash flood forecasting in and around Australia’s capital cities. Current precipitation estimates suffer from the limited availability of rain gauge data and the uncertainties linked to weather radar derived rainfall products. Commercial Microwave Links received signal attenuation can be related rainfall intensity, meaning that these data may be used to supplement the shortfall in raingauge data. In this project, we develop the technology to generate precipitation maps using the combination of mobile phone network link, rain gauge and weather radar data. We are using Metropolitan Melbourne as our experimental region using high-resolution observations of rainfall (drop size distribution), high-end sensing instruments (microwave scintillometer) and our high-resolution dual polarisation weather radar (X-Band). We work closely with Melbourne Water, the Bureau of Meteorology and the Hydrology and Water Management Group at Wageningen University in The Netherlands.

Wildfire-atmosphere: Weather radar to monitor wildfire plumes and pyro-convection

The Bushfire Convective Plume Experiment started in 2014 with the support of The University of Queensland (a University-Industry funding with the Bureau of Meteorology and Queensland Fire and Emergency Services, a UQ Fellowship for myself and a PhD support from the Australian government and Advanced Queensland for Mr Nicholas McCarthy). Since then, and with the additional support of the Country Fire Authority and the New South Wales Rural Fire Service, we have been monitoring interactions between wildfires and the atmosphere, using a combination of observations (ground observations, fire behaviour, plume and background atmosphere observations using a portable X-Band weather radar), in Victoria, Queensland and New South Wales at a number of fire and prescribed burns (see the first results of the BCPE in the publication section) .

Water resources on coral cays: science to underpin sustainable management

Coral cays are found throughout tropical and subtropical marine environments, many supporting human populations and vulnerable ecosystems (such as Marshall Islands and the Great Barrier Reef). A shallow and often brackish-fresh groundwater lens supports terrestrial vegetation that colonizes the cays. Many factors affect the size of these lenses, such as changes in sea level, rainfall, evapotranspiration and groundwater extraction. Vegetation type and distribution can have a significant effect on the size of the freshwater lens, due to losses from transpiration, and the amount of groundwater recharge from precipitation. In this project, we are quantifying groundwater-vegetation-atmosphere interactions for coral cays, using Heron Island (southern part of the Great Barrier Reef) as our research site. The primary objectives are: (i) to identify the processes controlling the freshwater balance of a coral cay; and (ii) to establish a water balance model characterizing the response of vegetation to changes in freshwater quantity and quality. 

Water resources and eco-hydrology of sand mass barrier islands

On the East Coast of Australia lie the largest sand islands in the world: Fraser Island, Bribie Island, Moreton, North and South Stradbroke Islands. These coastal environments located close to major Australian cities (Brisbane and the Gold Coast) present unique and fragile ecosystems. Together with my colleagues at The University of Queensland and at the National Centre for Groundwater Research and Training, including PhD students, visiting students and academic colleagues, I have been studying the link between groundwater, vegetation and land-atmosphere interactions for these systems, using a combination of monitoring and modelling approaches. In particular, I focused on:

Perched vegetated lakes and wetlands

Hydrologically unique ecosystems, these perched lake lie on a low permeability layer of a couple of meters thick (peat or coffee-rock) which enables water to remain all year-long. How resilient are they to climate variability, what are the processes driving recharge? We deployed advanced sensors: an infrared scintillometer, a sonic anemometer and multiple sensor in a remote lake to quantify fluxes and storage or energy and water.

Native vegetation eco-hydrology

Mangroves are one of the most fascinating tree species, able to tolerate and growth in salty environments, with very little access to freshwater.  We studied Mangroves on the East coast of Australia, monitored their water usage and stress, and found fascinating behaviours (see the results in my publications).

Plantations and the hydrology of the islands

On some of these islands, native vegetation has been replaced by pine plantations, with fast growing species to produce softwood timber. How does it change the hydrology of the islands? What is the water use and how does it compare with Native Species? We have conducted extensive observations combined with modelling to find out (see my publications).

Vegetation moisture content and its relation to flammability: An in-situ approach

This project is using in-situ electromagnetic techniques (ERT, FDR) and in-situ tree hydraulic functioning sensors to characterise the variability of tree moisture content across time and space. In parallel, a characterisation of the wood flammability in relation to moisture content is evaluated.

Peer reviewed journal articles

[27] McCarthy, N., Guyot, A., Protat, A., Dowdy, A. and H. McGowan. Tracking Pyrometeors with weather radar using unsupervised machine learning. Geophysical Research Letters, doi: 10.1029/2019GL084305. Copyright 2019 American Geophysical Union.

[26] Pauwels, V.R.N., Guyot, A. and J.P. Walker. Evaluating model results in scatter plots: A critique . Letter to the Editor, Ecological Modelling, doi.org/10.1016/j.ecolmodel.2019.108802. Copyright 2019 Elsevier Science Ltd.

[25] Terrasson, A., McCarthy, N., Dowdy, A., Richter, H., McGowan, H. and A. Guyot (2019) Weather radar insights into the turbulent dynamics of a supercell thunderstorm. Manuscript accepted in Journal of Geophysical Research: Atmospheres, https://doi.org/10.1029/2018JD029986. Copyright 2019 American Geophysical Union.

[24] Marchionni, V., Guyot, A., Tapper, N., Walker J.P. and E. Daly (2019) Tree water use dynamics in remnant urban reserves.  Journal of Hydrology, 575, 343-353, doi.org/10.1016/j.jhydrol.2019.05.022 Copyright 2019 Elsevier Science Ltd.

[23] McCarthy, N., Guyot, A., Dowdy, A. and H. McGowan (2018) Wildfire and Weather radar: a review. Journal of Geophysical Research: Atmospheres, doi.org/10.1029/2018JD029285 Copyright 2018 American Geophysical Union.

[22] Gray, M., McGowan, H., A. Guyot and D.A. Lockington (2018) Impacts of fire and flood on land-atmosphere energetics in a subtropical coastal ecosystem. Boundary Layer Meteorology, doi.10.1007/s10546-018-0414-y.

[21] Steppe, K., Vandegehuchte, M., Van de Wal, B., Hoste, P., Guyot, A., Lovelock, C.E. and D.A. Lockington (2018) Direct uptake of canopy rainwater causes turgor-driven growth spurts in the mangrove Avicennia marina. Tree Physiology, Volume 38, Issue 7, 1 July 2018, Pages 979 991, doi.org/10.1093/treephys/tpy024. Copyright 2018 Oxford Publishing Group.

[20] McCarthy*, N., H. McGowan, Guyot, A. and A. Dowdy (2018) Mobile X-POL radar observations of pyroconvection: A new tool for gaining insight to lure dynamics and bushfire meteorology. Bulletin of the American Meteorological Society, doi.org/10.1175/BAMS-D-16-0118.1. Copyright 2018 American Meteorological Society.

[19] Fan*, J., Guyot, A., Oestergaard, K.T. and D.A. Lockington (2017)  Effect of hydraulic architecture on sap flux density- based transpiration estimates in conifers. Journal of Agricultural and Forest Meteorology, doi.org/10.1016/j.agrformet.2017. Copyright 2017 Elsevier Science Ltd.

[18] Gray*, M., McGowan, H., Lowry, A. and A. Guyot (2017) Surface energy exchanges of contrasting vegetation types on a subtropical sand island. Journal of Agricultural and Forest Meteorology. Copyright 2017 Elsevier Science Ltd.

[17] Guyot, A., Oestergaard, K.T., Whitley, R., Fan, J., Arsac, M., Gibbes, B. and D.A. Lockington (2017) Soil- water content characterization in a modified Jarvis-Stewart model: a case study for shallow unconfined aquifer plantation forest. Journal of Hydrology 544, 242-253. Copyright 2017 Elsevier Science Ltd.

[16] Fan* J., Oestergaard K.T., Guyot A., Fujiwara, S. and D.A. Lockington (2016) Estimating groundwater evapotranspiration by a subtropical pine plantation using diurnal water table fluctuations: Implications from night-time water use. Journal of Hydrology 542, 679-685. Copyright 2016 Elsevier Science Ltd.

[15] Wang, H., Guan, H., Guyot, A., Lockington, D.A. and C.T. Simmons (2016) Quantifying sapwood areas for three Australian native species using electrical resistivity tomography. Ecohydrology 9 (1), 83-92.

[14] Fan* J., Oestergaard K.T., Guyot A., Jensen D.G. and D.A. Lockington (2015) Spatial variability of throughfall and stemflow in an exotic pine plantation of subtropical coastal Australia. Hydrological Processes 29 (5), 793–804.

[13] Fan*, J., Scheuermann, A., Guyot, A., Baumgart T. and D.A. Lockington (2015) Quantifying spatiotemporal dynamics of root-zone soil moisture in a mixed forest on subtropical coastal sand dune using surface ERT combined with spatial TDR. Journal of Hydrology 523, 475-488. Copyright 2015 Elsevier Science Ltd.

[12] Guyot, A., Oestergaard, K.T., Santini, N.S., Fan, J. and D.A. Lockington (2015) Xylem hydraulic properties in subtropical coniferous trees influence radial patterns of sap flow: Implications for whole tree transpiration estimates using sap flow sensors. Trees – Structure and Function 29 (4), 961-972. Copyright 2015 Springer Publishing Group.

[11] Van de Wal*, B.A.E., Guyot, A., Lovelock, C.E., Lockington D.A. and K. Steppe (2014) Influence of temporospatial variation in sap flux density on estimates of whole-tree water use in Avicennia marina. Trees – Structure and Function 29 (1), 215-222. Copyright 2014 Springer Publishing Group.

[10] Fan* J., Oestergaard K.T., Guyot A. and D.A. Lockington (2014) Measuring and modeling rainfall interception losses by a native Banksia woodland and an exotic pine plantation in subtropical coastal Australia. Journal of Hydrology 515, 156-165. Copyright 2014 Elsevier Science Ltd.

[9] Fan* J., Oestergaard K.T., Guyot A. and D.A. Lockington (2014) Estimating groundwater recharge and evapotranspiration from water table fluctuations under three vegetation covers in a coastal sandy aquifer of subtropical Australia. Journal of Hydrology 519, 1120-1229. Copyright 2014 Elsevier Science Ltd.

[8] Vandegehuchte M.W., Guyot A., Hubeau, M., De Groote, S.R.E., De Baerdemaeker, N.J.F., Hayes, M., Welti, N., Lockington, D.A. and K. Steppe (2014) Long-term versus daily stem diameter variation in co-occurring mangrove species: Environmental versus ecophysiological drivers. Agricultural and Forest Meteorology 192-193, 51-58. Copyright 2014 Elsevier Science Ltd.

[7] Vandegehuchte, M.W., Guyot, A., Hubeau, M., De Swaef, T., Lockington, D.A. and K. Steppe (2014) Modelling reveals endogenous osmotic adaptation of storage tissue water potential as an important driver determining different stem diameter variation patterns in the mangrove species Avicennia Marina and Rhizophora Stylosa.  Annals of Botany 114 (4), 667-676. Copyright 2014 Oxford Academics Publishing Group.

[6] Hubeau, M., Vandegehuchte, M., Guyot, A., Lovelock, C., Lockington, D.A. and K. Steppe (2014) Plant-water relations of the Mangrove Rhizophera Stylosa: A Unique Story.  Communications in Applied Biological Sciences 79/1.

[5] Guyot A., Oestergaard K.T., Lenkopane M., Fan J. and D.A. Lockington (2013) Using electrical resistivity tomography to differentiate sapwood from heartwood: application to conifers. Tree Physiology 33 (2), 187-194. Copyright 2013 Oxford Academics Publishing Group.

[4] Guyot A., Cohard J.-M., Anquetin S. and S. Galle (2012) Long-term observations of turbulent fluxes over heterogeneous vegetation using scintillometry and additional observations: A contribution to AMMA under Sudano-Sahelian climate. Agricultural and Forest Meteorology 84, 154-155. Copyright 2012 Elsevier Science Ltd.

[3] Séguis L., Boulain N., Cappelaere B., Cohard J. M., Favreau G., Galle S., Guyot A., et al. (2011) Contrasted land‐surface processes along the West African rainfall gradient. Atmospheric Science Letters 12 (1), 31-37. Copyright Royal Meteorological Society 2011.

[2] Descloitres M., Séguis L., Legchenko A., Wubda M., Guyot A. and J.-M. Cohard (2011) The contribution of MRS and resistivity methods to the interpretation of actual evapo-transpiration measurements: a case study in metamorphic context in north Benin.  Near Surface Geophysics 9 (2), 187-200. Copyright EAGE 2011.

[1] Guyot A., Cohard J.-M., Anquetin S., Galle, S. and C.R. Lloyd (2009) Combined analysis of energy and water balances to estimate latent heat flux of a Sudanian small catchment.  Journal of Hydrology 375 (1-2), 227-240. Copyright 2009 Elsevier Science Ltd.

Journal articles under review

Guyot, A., Pudashine, J., Protat, A., Uijlenhoet, R., Pauwels, V.R.N., Seed, A. and J.P. Walker. Effect of disdrometer type on rain drop size characterisation: a new dataset for Southeastern Australia. Manuscript in Discussion in Hydrology and Earth System Sciences.

Tao, W., Chen, J., Zhang, C., Guyot, A. and L. Li. Global water vapor paths uncovered by isotopes entropies. Manuscript under review in Global and Planetary Change.

Conferences and seminars

Guyot, A., Pudashine, J., Pauwels, V., Protat, A., Seed, A.,  M. Prakash, Uijlenhoet, R. and J. Walker (2018) Raindrop size distribution in coastal rainfall systems in South-East Australia. European Conference on Radar in Meteorology, July 2018.

Guyot, A., Pudashine, J., Pauwels, V., Seed, A., M. Prakash, Uijlenhoet, R., and J. Walker (2017) A review of the current trend in the application of microwave links for hydrology. MODSIM 2017 Hobart, Proceedings of Conference.

Pudashine, J., Guyot, A., Walker, J., Pauwels, V., Seed, A., M. Prakash, Uijlenhoet, R. and J. Walker (2017) Rainfall derived from a dense network of Commercial Microwave Links: A case study for Melbourne. MODSIM 2017 Hobart, Proceedings of Conference.

McCarthy*, N., Guyot, A., McGowan, H. and A. Dowdy (2017) The use of spectrum width radar data for bushfire model verification. Conference paper accepted in MODSIM 2017 Hobart, Proceedings of Conference.

Guyot, A., Pudashine, J., Uijlenhoet, R., Walker, J., Pauwels, V., Seed, A. and M. Prakash (2017) Improving rainfall products using mobile phone telecommunication links. Monash-Selex conference November 2017.

Guyot, A. (2017) Science to underpin sustainable management of freshwater resources on coral cays. Invited talk at Heron Island Resort July 2017.

Guyot, A., McCarthy, N., McGowan, H. and A. Dowdy (2016) Weather radar and wildfires: What we know and what we don’t. Selex-Germatronik 2016 weather radar conference.

McCarthy, N., McGowan, H. and A. Guyot (2016) The bushfire convective plume experiment: mobile radar observations of pyro-convection from the Mt Bolton fire, 2016, AFAC 16 (Bushfire and Natural Hazards CRC, 2016), Brisbane Convention Centre.

Guyot, A. (2016) Advances in environmental sensing in the fields of water and fire. Invited speaker at the School of Civil Engineering at Monash University (August 2016).

Guyot, A., McGowan, H., Gray, M., Riesenkamp, M. and D.A. Lockington (2016) Impacts of extreme weather

conditions on the water and energy balance of a subtropical wetland EGU General Assembly, Vienna 2016.

Guyot, A., McGowan, H., Gray, M., Riesenkamp, M. and D.A. Lockington (2015) Coastal wetland energy and water balances for a better understanding of ecohydrological processes: a case study in a sensitive socio-economic context in Australia. HydroEco Conference, Vienna 2015.

Guyot, A., White, M. Vandegehuchte, M., Steppe, K. and D.A. Lockington (2013) Atmosphere Vegetation- Groundwater interactions: A case study in the context of the subtropical coastal sandy mass aquifers from Eastern Australia. EGU General Assembly Conference, Vienna 2013.

Guyot, A. (2013) Monitoring and modeling evapotranspiration: experience gained from 2 years of research in Australia. Invited speaker at Joseph Fourier University (January 2013).

Guyot, A. (2012) Monitoring and modeling evapotranspiration: perspectives and implications for water management issues. Invited speaker at Ghent University (December 2012).

Guyot, A., Oestergaard, KT, Lenkopane, M., Fan, J. and D.A. Lockington (2011) A method to improve tree water use estimates by distinguishing sapwood from heartwood using Electrical Resistivity Tomography. AGU Fall Meeting 2011, December 15-19th, San Francisco (Poster).

Guyot, A., Cohard, J.-M. , Doukoure, M., Anquetin, S. and S. Galle (2009) Three year time series of sensible and latent heat fluxes over a patchy savannah in West Africa using Large Aperture Scintillometer measurements. 3rd AMMA International Conference 2009, Ouagadougou, Burkina Faso (Poster).

Guyot, A., Cohard, J.-M., Doukoure, M., Anquetin, S. Galle, S. and I. Zin (2009) Footprint variability analysis of a Large Aperture Scintillometer over a complex terrain. EGU general assembly, Vienna 2009 (Poster).

Guyot, A., Cohard, J.-M., Anquetin and S. Galle (2009) Three years of Large Aperture Scintillometer measurements over a patchy savanna in West Africa EGU general assembly, Vienna 2009 (Speaker).

Guyot, A., Cohard, J.-M., Anquetin and S. Galle (2007) Energy and water balance at catchment scale: a case study.2nd AMMA International conference, Karlsruhe, 2007 (Speaker).

Guyot, A., Cohard, J.-M. and S. Galle (2007) Energy balance at catchment scale using an infrared scintillometer and soil measurements. EGU general assembly, Vienna 2007 (Poster).

Reports and media communications

McCarthy*, N., H. McGowan and Guyot, A. Portable weather radar: Fire Away. Meteorological Technology International.

Guyot, A. (2014) Scientists study Straddie wetland. Sandtimes (A publication of the Sibelco Cie).

Guyot, A. (2011) Quel avenir pour les ressources en eaux souterraines en Australie ? Le monde Supplement Partenaire.

Guyot, A. (2010) Estimation de l’evapotranspiration sur un couvert complexe par utilization de la scintillometrie infrarouge : Application a un bassin versant de zone soudano-sahelienne (Benin). These de doctorat, Universite de Grenoble.

Guyot, A. (2006) Evaluation du flux de chaleur latente à l’échelle du bassin versant. Fermeture du bilan en énergie à l’aide d’un scintillometre infrarouge. Rapport de Master 2 Recherche, Universite de Grenoble.

Guyot, A. (2005) Identifying the carrier of remnant magnetism in archeological material: laboratory measurements of Mesopotamian potteries fragments. Rapport de Master 1, Ecole Normale Superieure (Paris) – Institute for Rock Magnetism (USA).

2015-2016 UQ CIEF Grant, $81k

2014-2016 UQ Fellowship Grant, $340k

2013-2014 UQ Summer internship students, $6k

2013 NCGRT Research Award

2006-2009 CNRS BDI Scholarship Grant, Euro 90k

Supervision

PHD

Mr Lutfi Ramadhan at The University of Queensland
The role of moisture and the water cycle on the flammability of vegetation and the risk of bushfires (with Dr Juan Hidalgo and Dr Andres Osorio)
2018 to 2021

Mr Jaya Pudashine at Monash University
Improving rainfall products using Mobile Phone Received Signal Level data
2016 to 2019

Mr Nicholas McCarthy at The University of Queensland
Integrating weather radar data in the comprehension of pyroconvection and wildfire-weather interactions
2016 to 2019

Dr Junliang Fan at The University of Queensland
Hydrology of subtropical sand barrier islands
2010 to 2014

Dr Kasper Oestergaard at The University of Queensland
Quantifying woody vegetation water use in subtropical groundwater systems
2010 to 2014

Undergraduate

Mr Valentin Orus (Ecole Centrale de Lyon) at Monash University
Visiting student
2018 to 2018

Mr Alex Terrasson (Ecole Centrale de Lyon) at The University of Queensland
Visiting student
2017 to 2017

Mr Stanislas Badatcheff (Ecole Centrale de Lyon) at The University of Queensland
Visiting student
2016 to 2016

Mr Roland Barthelemy (Ecole Centrale de Lyon) at The University of Queensland
Visiting student
2016 to 2016

Mr Matthieu Colombu (Ecole Centrale de Lyon) at Monash University of Queensland
Visiting student
2015 to 2015

Miss Roxanne Caillaud (Ecole Centrale de Lyon) at The University of Queensland
Visiting student
2012 to 2012

Mr Alexis Gertz (Ecole Centrale de Lyon) at Monash University of Queensland
Visiting student
2011 to 2011

Miss Marcilla Pena at The University of Queensland
Visiting student
2014 to 2015

Mr Pankaj Thakur at The University of Queensland
Visiting student
2014 to 2015

Mr Louis Jalenques (Ecole Centrale de Lyon) at Monash University
Visiting student
2019 to 2019

Mr Bruno Millet (Ecole Centrale de Lyon) at Monash University
Visiting student
2019 to 2019

Mr Rounak Dalal (Monash University)
Final Year Student
2019 to 2019

Masters

Mr Martin Aubrun (Ecole Centrale de Lyon) at The University of Queensland
Water resources on subtropical coral cays
2017 to 2017

Staff

Mr Jeremy Canard at The University of Queensland
Research Officer
2011 to 2013

Mr Michiel Riesenkamp at The University of Queensland
Research Officer
2014 to 2015

Teaching Commitments

  • 2019 - Topical Lecturer for the Master course unit CIV5883 & CIV6883 - Surface Hydrology at Monash University
  • 2018 - Course Coordinator for the Master course unit CIV5883 & CIV6883 - Surface Hydrology at Monash University
  • 2017 - Guest lecturer for unit CIV4268 - Water Management at Monash University
  • 2014 - Guest lecturer for unit CIV4180 - Sustainable Built Environment at The University of Queensland
  • 2011-2014 - Guest lecturer and tutor for CIV2140 - Catchment Hydrology at The University of Queensland

PhD Thesis

Evapotranspiration estimation over a complex surface by the use of infrared scintillometry: Case study of a Sudano-Sahelian watershed (Benin)

PhD Thesis awarded at The University of Grenoble in 2010 (University Joseph Fourier) (in French)

Abstract

Global climate changes, and the increase of anthopogenic constraints on the environment, are creating more and more pressure on water ressources, especially in the arid and semi-arid regions, already severely affected by climatic hazards. In those regions, land-atmosphere feedbacks are one of the most important mecanism of precipitation regulation, and so the water supply, for short and long time scales. These regions have evapotranspiration rates of high temporal and spatial variability. Evapotranspiration is a major component of the water and the energy balance. This term represents at the global scale 80% of the energy exchanges in the atmosphere, and at least 50% of the energy balance at the land-atmosphere interface. Furthermore, from our days knowledge, this term is major in the water balance in arid environments. Despite that strong need, evapotranspiration is still very un-quantified, and is very difficult to estimate over natural landscapes, with complex topography and vegetation heterogeneities. Recent progress in instrumental techniques, bring a new hope using scintillometry to evaluate evaporative fluxes at the scale of km and for complex surfaces. The present work presents an observational approach using infrared scintillometry coupled with an energy balance, to estimate evaporative fluxes at the scale of a 12 km square watershed, under a Sudanian climate, in the frame of the AMMA program (African Monsoon Multidisciplinary Analyses). The work is based on two axis: (1) the first part presents an overview of the experimental environment, with a climatology, and surface aerodynamic characterization, to prepare the construction of the methodology of estimating fluxes trough scintillometry and energy balance; (2) then, the turbulent fluxes variability over three years is explored across three sections: (i) a first study on the variability of the turbulent and radiative fluxes and surface conditions; (ii) a case study around an isolated rainfall in the dry season, show the cross dynamics of both evapotranspiration and soil water; (iii) an hydrologic study looking at the water balance at the catchment scale.

Résumé

Les modifications climatiques globales, et l’augmentation des contraintes démographiques créent une pression de plus en plus forte sur les ressources en eau, en particulier dans les régions arides et semi-arides, déjà fortement dépendantes des aléas climatiques. Dans ces régions, les rétroactions entre le sol et l’atmosphère sont un des mécanismes fondamentaux de régulation des précipitations, et donc de l’apport en eau, à court et à long terme. Ces régions ont des taux d’évapotranspiration de forte variabilité temporelle et spatiale. Celle-ci est une composante majeure du bilan en eau, et du bilan en énergie. Elle représente au niveau global 80 % des échanges énergétiques dans l’atmosphère, et au moins 50 % du bilan énergétique à la surface de la Terre. De plus, d’après les observations disponibles à ce jour, elle est le terme principal du bilan en eau dans les régions arides. Pour autant, elle reste très mal quantifiée, et est extrêmement difficile à estimer sur des surfaces naturelles, complexes, hétérogènes, et avec de la topographie. De récents progrès instrumentaux apportent un espoir quant à l’utilisation de la scintillométrie pour évaluer les flux évaporatifs à des échelles de plusieurs km2, sur ce type de surfaces. Cette thèse présente une démarche d’observation, par scintillométrie infrarouge et bilan d’énergie, des flux évaporatifs à l’échelle d’un bassin versant en climat soudano sahélien, dans le cadre du programme AMMA d’étude de la mousson en Afrique de l’Ouest. Cette thèse est articulée autour de deux axes : (1) une première partie présente une caractérisation aérodynamique de la surface d’étude, pour préparer la mise en place de la méthodologie de calculs des flux par scintillométrie, et bilan d’énergie ; (2) Ensuite, la variabilité des flux turbulents sur trois années est explorée à travers trois volets : (i) une étude sur la relation entre les conditions de surface et les flux radiatifs et turbulents ; (ii) une étude de cas sur une pluie en saison sèche montre la dynamique de l’eau dans le sol et l’évaporation ; (iii) une étude hydrologique sur le bilan en eau à l’échelle du bassin versant.

 

Curriculum Vitae

 

 

 

Last modified: 25/09/2019