Homepage Emily Walker

Ingénieure de recherche INRA

  • CONTACT

INRA
Unité de Biostatistique et Processus Spatiaux (BioSP)
228 route de l’aérodrome
CS 40509
Domaine St-Paul - Site Agroparc
84914 Avignon Cedex 9

Tel: +33 4 32 72 21 74
Fax: +33 4 32 72 21 82
emily.walker_at_inra.fr

 

  •  RESEARCH INTERESTS - RESEARCH FIELDS

Statistics: spatial statistics, Bayesian approach, Markov chains, multivariate analyses, spatio-temporal statistics, state-space model

Geostatistics (multivariate), mapping

Data analysis: high dimension data, geo-referenced data and remote sensing data (satellite / radar)

Agro-ecology, landscape ecology, soil science

Climate statistics

Population genetics

 

  • PROJECTS

COMPROMISE (ACCAF)

GESTER

AMIGA

Research networks: GdR EcoStat, “trajectories” group, “modelling for plants health” group (ModStatSAP), MEDIA network

Ecole-chercheurs BIOBAYES

 

  • SOFTWARES

R package

Walker E, Rey J, Leclerc M (2018). briskaR: Biological Risk Assessment in R. R package version 0.1.2, https://cran.r-project.org/package=briskaR

(briskaR est la nouvelle version du package précédent SEHmodel: Spatial Exposure-Hazard Model for Exposure and Impact Assessment on Exposed Individuals)

 

  • PREVIOUS POSITIONS AND EDUCATION

Post-doc INRA, ANR project GESTER (2016)

Post-doc INRA, EU-FP7 project AMIGA (2013-2015) - Spatially-explicit exposure-hazard model to assess genetically modified (GM) maize effects on non target organisms mortality (Lepidopterian) at a regional scale.

Post-doc INRA, ANR project PEERLESS (2012-2013) - Biostatistics for spatio-temporal population dynamic models from genetic data

Post-doc IFREMER, AMPED project (2011-2012) - Etude de la répartition spatiale du merlu (Merluccius merluccius) dans le Golfe du Lion à partir des données de marquage, et conséquences de l’instauration d’une zone de pêche réglementée

Post-doc INRA, ANR projects ISPOS-SEAL and DIGISOL-HYMED (2010-2011) - Geostatistical modelling of the spatio-temporal distribution of fluorescence and primary productivity in Southern Ocean in areas sampled by elephant seals (ANR IPSOS-SEAL) -- Geostatistical modelling and interpolation of characteristics and soil classes at fine scale from multispectral data (ANR DIGISOL-HYMED)

PhD Student, IRD (Institute of Research on Development) – Mines Paris Tech (2007-2010) - From predators trajectories to preys maps: spatial estimation of purse-seiners activity and tuna in the Indian Ocean.

Link (pdf): http://hal.archives-ouvertes.fr/docs/00/55/21/83/PDF/Walker.pdf

Master degree Statistics and Econometrics Toulouse University

 

  • PUBLICATIONS (updated april 2019)

Publications dans des revues de rang A

Walker, E., Leclerc, M., Rey, J.-F., Beaudouin, R., Soubeyrand, S., Messean, A. (2019). A Spatio-Temporal Exposure-Hazard Model for Assessing Biological Risk and Impact. Risk Analysis, 39 (1), 54 - 70. , DOI : 10.1111/risa.12941

Leclerc, M., Walker, E., Messean, A., Soubeyrand, S. (2018). Spatial exposure-hazard and landscape models for assessing the impact of GM crops on non-target organisms. Science of the Total Environment, 624, 470 - 479. , DOI : 10.1016/j.scitotenv.2017.11.329

Walker, E., Monestiez, P., Gomez, C., Lagacherie, P. (2017). Combining measured sites, soilscapes map and soil sensing for mapping soil properties of a region. Geoderma, 300, 64-73. , DOI : 10.1016/j.geoderma.2016.12.011

Roques, L., Walker, E., Franck, P., Soubeyrand, S., Klein, E. (2016). Using genetic data to estimate diffusion rates in heterogeneous landscapes. Journal of Mathematical Biology, 73 (2), 397-422. , DOI : 10.1007/s00285-015-0954-4

Penczykowski R.M., Walker E., Soubeyrand S., Laine AL. 2015. Linking winter conditions to regional disease dynamics in a wild plant–pathogen metapopulation. New Phytologist, 205(3), pp. 1142-1152.

Walker E., Rivoirard J., Gaspar P., Bez N. 2015. From forager tracks to prey distributions: an application to tuna Vessel Monitoring Systems (VMS). Ecological Applications, 25(3), 2015, pp. 826–833.

Dagorn L., Bez N., Fauvel T., Walker E. 2013. How much do fish aggregating devices (FADs) modify the floating object environment in the ocean? Fisheries Oceanography, 22 (3), p. 147-153. Doi: 10.1111/fog.12014

Guinet C., Xing X., Walker E., Monestiez P., Marchand S., Picard B., Jaud T., Authier M., Cotté C., Dragon A.C., Diamond E., Antoine D., Lovell P., Blain S., D'Ortenzio F., Claustre H. 2013. Calibration procedures and first data set of Southern Ocean chlorophyll-a profiles collected by elephant seal equipped with a newly developed CTD-fluorescence tags. Earth Syst. Sci. Data, 5, 15-29. Doi: 10.5194/essd-5-15-2013

Bez N., Walker E., Gaertner D., Rivoirard J., Gaspar P. 2011. Fishing activity of tuna purse seiners estimated from vessels monitoring system (VMS) data. Canadian Journal of Fisheries and Aquatic Sciences, 68 (11), p. 1998-2010.

Walker E. and Bez N. 2010. A pioneer validation of a state space model of vessel trajectories (VMS) with observers’ data. Ecological Modelling 221, pages 2008-2017.

 

Chapitre d’ouvrage, Publications dans des actes de colloques (avec ou sans comité de lecture)

Ciampalini, R., P. Lagacherie, P. Monestiez, E. Walker, C. Gomez. 2012. Co-kriging of soil properties with Vis-NIR hyperspectral covariates in the Cap Bon region (Tunisia). DSM2012. In: Digital Soil Assessments and Beyond (ed Patrice E. Carbonneau and Hervé Piégay), Vol. 418, pp 393-398, CRC Press.

Walker E., Monestiez P., Gomez C., Lagacherie P. 2012. Cokriging for Large Spatial Datasets: Mapping Soil Properties at a Region Scale from Airborne Hyperspectral Imagery. Ninth International Geostatistics Congress, Oslo, Norway, June 11 – 15, 2012.

Bez N., Walker E., Gaertner D., Rivoirard J., Gaspar P. 2010. From VMS data to tuna distribution maps and indices of abundance. IOTC (Indian Ocean Tuna Commission). 2010 WPTT-21.

Fauvel T., Bez N., Walker E., Delgado A., Murua H., Chavance P., Dagorn L. 2009. Comparative study of the distribution of natural versus artificial drifting Fish Aggregating Devices (FADs) in the Western Indian Ocean. IOTC (Indian Ocean Tuna Commission). 2009 WPTT -19.

Walker E., Monestiez P., Renard D., Bez N. 2008. Kriging of the latent probability of a binomial variable: application to fish statistics. VIII International Geostatistics Congress, Santiago de Chile, Chile. 1 December 2008.

 

Présentations orales et posters dans des conférences internationales et nationales

Walker, E., Papaix, J., Klein, E., Bonnefon, O., Franck, P. (2017). Estimation bayésienne de fréquences alléliques dans un modèle de métapopulation. Presented at 49.Journées de Statistique. JDS 2017, Avignon, FRA (2017-05-29 - 2017-06-02).

Walker E., Antoine Messéan, Samuel Soubeyrand, Melen Leclerc, Jean–Francois Rey . 2016. A spatio-temporal exposure-hazard model for assessing the impact of Genetically Modified (GM) plants pollen on non-target organisms. International Statistical Ecology Conference (ISEC), Seattle, June 2016.

Walker E., Messéan A., Soubeyrand S., Leclerc M., Rey J-F. 2016. A modelling framework for assessing lethal and sublethal effects of GM maize pollen on non target Lepidoptera. Future for Butterflies Conference. Wageningen, Netherlands, 31 mars-2 avril 2016.

Walker E., Monestiez P., Gomez C., Lagacherie, P. 2015. Combining measured sites, soil map and soil sensing for mapping soil properties of a region. Pedometrics 2015, 14-18 Septembre 2015, Córdoba, Espagne.

Walker E., Soubeyrand S., Leclerc M., Messéan A. 2015. A stochastic geometry-based modelling framework for assessing spatio-temporal ecotoxicological risks at the landscape scale: The impact of Bt maize on non-target Lepidoptera as an example system. Spatial Statistics Conference, 9-12 juin 2015, Avignon, France.

Walker E., Bez N. 2015. De la trajectoire des thoniers senneurs à la cartographie des thons tropicaux. Colloque de l’Association Française d’Halieutique (AFH), 1-3 juillet 2015, Montpellier, France.

Walker E., Bez N., Rivoirard J. 2014. Cokriging of proportions to estimate tuna distribution from vessels’ trajectories. 10th conference on geostatistics for environmental applications (GeoENV 2014), Paris, 7-10 juillet 2014.

Walker E., Klein E., Roques L., Franck P., Soubeyrand S. 2014. Estimation of demographic parameters of an insect pest in apple-orchards landscape from genetic markers data. International Statistical Ecology Conference (ISEC), Montpellier, 1-4 juillet 2014.

Mahevas S., Bez N., Bertrand S., Capello M., Delattre M., De Pontual H., Dragon A.C., Drouineau H., Etienne M.P., Fablet R., Fromentin J.M., Gloaguen P., Joo R., Marzuki M., Maufroy A., Monestiez P., Nerini D., Rivot E., Thiebault A., Vermard Y., Walker E., Woillez M. 2014. Validation data: keystone to move state-space models for movements to operational models for fisheries and marine ecology. ISEC 2014 - 4th International Statistical Ecology Conference, 1-4 July 2014, Montpellier.

Monestiez P., Walker E., Gomes C., Lagacherie P. 2011. Multivariate geostatistical model to map soil properties at a region scale from airborne hyperspectral imagery and scattered soil field surveys: dealing with large dimensions. Spatial Conference: Spatial Data Methods for environmental and Ecological Processes. Foggia (Italy), 1-2 septembre 2011.

Tew Kai E., Walker E., van der Lingen C.D., Coetzee J., Bez N., van der Westhuizen J., and Grémillet D. 2011. Analysing fishing patterns of purse-seiners in the southern Benguela using Vessel Monitoring Systems (VMS). 14th South African Marine Science Symposium (SAMSS). Estuarine, coastal and oceanic ecosystems: Breaking down from the boundaries, 4 - 7  April 2011.

Walker E., Dragon A.C., Bailleul F., Marchand S., Fedak M., Lowell P., Xing X., D’Ortenzio F., Claustre H., Blain S., Monestiez P., Guinet C. 2010. Estimation of chlorophyll-a fields from Southern Elephant Seals sensors : interpolation of fluorescence dives profiles. International Council for the Exploration of the Sea (ICES) Annual Science Conference, Nantes, 20-24 septembre 2010.

Bez N., Walker E. 2010. De la trajectoire des prédateurs (thoniers senneurs) à la cartographie de leurs proies (thons tropicaux). Colloque Ecologie 2010, Montpellier, 2-4 septembre 2010.

Bez N., Walker E. 2010. From VMS to fishing effort and prey distribution. Fisheries Dependent Information Conference, Galway, Ireland, 23-26 août 2010.

Walker E., Mortier F., Gaspar P., Gaertner D., Pianet R., Bez N. 2008. Estimation of nominal fishing effort of tropical tuna purse seiners from VMS data. ICES Annual Science Conference, Halifax, Canada, September 2008.

Pianet R., Chavance P., Amande J. M., Walker E., Bez N. 2007. The French tropical purse seine fisheries observer program. Poster presented in the 5th international conference on observers program, Canada, May 2007.

 

Rapports techniques

Walker E., Soubeyrand S. 2016. Hamiltonian Monte Carlo in practice. Research report n°49. http://www.biosp.org/RR2016_49.pdf.

Walker E., Gaertner D., Gaspar P., Bez N. 2010. Fishing activity of tuna purse-seiners estimated from VMS data and validated by observers' data. In: Tropical tunas. Madrid: ICCAT, 2010, 65 (6), p. 2376-2391. (Collective Volume of Scientific Papers; 6).

Walker E. 2008. Rapport de mission d’Observateur sur un thonier senneur de l’Océan Indien. IRD. Février 2008.

 

Présentations dans des groupes de travail / réseaux

Bonnefon O, Walker E. 2019. Environnement Méca-Stat et démo(s). Réunion annuelle du réseau ModStatSAP, Paris, 12 mars 2019.

Bonnefon O, Walker E. 2018. Projets basés sur l'approche mécanistico-statistique. Réunion du CATI IMOTEP, Lyon, sept 2018.

Presentations in "Hierarchical models" group of GdR EcoStat. 2016, 2017.

Walker E, Julien Papaïx, Etienne Klein, Olivier Bonnefon, Pierre Franck. 2017. Estimation bayésienne de fréquences alléliques dans un modèle de métapopulation. Journées du GDR Ecologie Statistique EcoStat, Nantes, FRA (2017-05-22 - 2017-05-23)

Bonnefon, O., Roques, L., Bourhis, Y., Franck, P., Klein, E., Parisey, N., Poggi, S., Ricci, B., Soubeyrand, S., Walker, E. (2017). Dynamiques de populations en milieu hétérogène : modèles et estimation de paramètres. Presented at Séminaire "Ecologisation des systèmes de productions agricoles pour renforcer le contrôle biologique des bioagresseurs", Paris, FRA (2017-11-27 - 2017-11-28).

Michel, L., Walker, E., Papaix, J. (2017). Evaluation de l’effet de la biodiversité cultivée sur l’incidence et la sévérité des épidémies en milieu agricole. Presented at Journées du GDR Ecologie Statistique EcoStat, Nantes, FRA (2017-05-22 - 2017-05-23)

Walker E., Collet C. 2015. Detecting behaviour changes of bees exposed to insecticides. Workshop “Moving2Gather”, Nantes, 7-10 décembre 2015.

Roques L, Walker E, Franck P, Soubeyrand S, Klein E. 2015. Estimating diffusion rates from genetic data. Réunion annuelle du Groupement de Recherche Ecologie Statistique (« EcoStat »), Lyon, 12-13 mars 2015.

Walker E, Klein E, Roques L, Franck P, Soubeyrand S. 2014. Estimation de paramètres de diffusion de populations d’insectes ravageurs dans un paysage hétérogène, à partir de données génétiques. Réunion annuelle du réseau ModStatSAP, Paris, 11 décembre 2014.

Walker E. Bonnefon O., Franck P., Klein E., Lavigne C., Olivares J., Soubeyrand S., Roques L. 2014. Etude de la dispersion de Lépidoptères dans un paysage hétérogène : une approche mécanico-statistique appliquée à des données génétiques. Poster Assemblée Générale du département Maths et Informatique Appliquées (MIA) de l’INRA, Lyon, 17-20 mars 2014.

Le Corre G., Walker E. 2011. Géolocalisation des Pêches Artisanales - Expérimentation du système RECOPESCA. CGPM, Workshop on the implementation of a vessel monitoring system (VMS) in the Mediterranean and Black Sea, Zagreb, Croatia, 28-30 novembre 2011.

Walker E. 2010. Application d’un modèle bayésien aux trajectoires de navires de pêche. Workshop Statistiques Bayésiennes au Sommet de Rochebrune, 28 mars-2 avril 2010.

Walker E. and Bez N. 2009. Des trajectoires VMS aux distributions spatiales de thons tropicaux. 9eme Forum AFH (French Fisheries and Statistics Association), Brest, France. July 2009.

Walker E. 2008. Rapport de mission d’Observateur sur un thonier senneur de l’Océan Indien. IRD. Février 2008.

Walker E., Bez N., Gaertner D., Pianet R. 2007. Tuna fisheries in the Indian Ocean: VMS data from French purse seiners. Meeting CEDER project, Reykjavik, Iceland, 3-4 Juillet 2007

Walker E., Bez N., Delgado de Molina A., Pianet R. Évolution de la répartition spatiale de la pêche thonière sous Dispositifs de Concentration de Poissons (DCP) dans l’Océan Indien (1984-2004). 8ème Forum AFH (French Fisheries and Statistics Association), June 2007 – La Rochelle, France.

Walker E., Bez N., Gaspar P. 2007. Satellite monitoring of fishing vessels as a tool to localize and estimate the fishing activity. 2nd APEC SAKE workshop on Satellite Application on fishery and Coastal Ecosystem, November 5-8 2007, Indonesia.

 

 

  • STUDENTS

Co-supervisor of a Master 2 student, 2017.

Co-supervisor of a ENSAI student (master 1), 2017.

Co-supervisor of a ENSAI student (master 1), 2016.

Co-supervisor of a Master student for internship (Agro Paris Tech), 2009.

Accueil de collégiens en stage d'observation

 

  • TEACHING

Course of statistics and probability for students at CNAM (Conservatoire National des Arts et Métiers), 42h, 2013-14, 2014-15, 2015-16.

Course of statistics and probability for students at Avignon University (Techniques de Commercialisation - IUT) 20h, 2014.

Course on statistics software « R » in the Seychelles Fishing Authority (SFA) for researchers and students in biology, 14h, 2009.

 

 

 

 

Updated April 2019