246 results on '"N. Pauwels"'
Search Results
2. Exotic beams produced by fast neutrons
- Author
-
F. Clapier, A. C. Mueller, J. Obert, O. Bajeat, M. Ducourtieux, A. Ferro, A. Horbowa, L. Kotfila, C. Lau, H. Lefort, S. Kandri-Rody, N. Pauwels, J. C. Potier, J. Proust, J. C. Putaux, C. F. Liang, P. Paris, A. C. C. Villari, R. Lichtenthäler, L. Maunoury, and J. Lettry
- Subjects
Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
First results from the research and development program PARRNE (Production d'Atomes Radioactifs Riches en NEutrons) are presented. Its aim is the investigation of the optimum conditions for the production of neutron-rich fission fragment beams extracted from thick targets irradiated by fast neutrons.
- Published
- 1998
- Full Text
- View/download PDF
3. A Customized and Automated Assignment Management and Marking System for Evaluating Student Performance in the STEM Disciplines.
- Author
-
Ashkan Shokri, Veronica Halupka, and Valentijn R. N. Pauwels
- Published
- 2021
- Full Text
- View/download PDF
4. The 3114: A new professional helpline to swing the French suicide prevention in a new paradigm
- Author
-
C-E. Notredame, M. Wathelet, M. Morgiève, P. Grandgenèvre, C. Debien, C. Mannoni, N. Pauwels, F. Ducrocq, E. Leaune, P. Binder, S. Berrouiguet, M. Walter, P. Courtet, G. Vaiva, and P. Thomas
- Subjects
suicide ,suicide prevention ,helpline ,Psychiatry ,RC435-571 - Full Text
- View/download PDF
5. The Soil Moisture Active Passive Experiments: Validation of the SMAP Products in Australia.
- Author
-
Nan Ye, Jeffrey P. Walker, Xiaoling Wu 0001, Richard de Jeu, Ying Gao 0002, Thomas J. Jackson, François Jonard, Edward Kim 0001, Olivier Merlin, Valentijn R. N. Pauwels, Luigi J. Renzullo, Christoph Rüdiger, Sabah Sabaghy, Christian von Hebel, Simon H. Yueh, and Liujun Zhu
- Published
- 2021
- Full Text
- View/download PDF
6. Perspective on Satellite-Based Land Data Assimilation to Estimate Water Cycle Components in an Era of Advanced Data Availability and Model Sophistication
- Author
-
Gabriëlle J. M. De Lannoy, Michel Bechtold, Clément Albergel, Luca Brocca, Jean-Christophe Calvet, Alberto Carrassi, Wade T. Crow, Patricia de Rosnay, Michael Durand, Barton Forman, Gernot Geppert, Manuela Girotto, Harrie-Jan Hendricks Franssen, Tobias Jonas, Sujay Kumar, Hans Lievens, Yang Lu, Christian Massari, Valentijn R. N. Pauwels, Rolf H. Reichle, and Susan Steele-Dunne
- Subjects
Earth Resources And Remote Sensing - Abstract
The beginning of the 21st century is marked by a rapid growth of land surface satellite data and model sophistication. This offers new opportunities to estimate multiple components of the water cycle via satellite-based land data assimilation (DA) across multiple scales. By resolving more processes in land surface models and by coupling the land, the atmosphere, and other Earth system compartments, the observed information can be propagated to constrain additional unobserved variables. Furthermore, access to more satellite observations enables the direct constraint of more and more components of the water cycle that are of interest to end users. However, the finer level of detail in models and data is also often accompanied by an increase in dimensions, with more state variables, parameters, or boundary conditions to estimate, and more observations to assimilate. This requires advanced DA methods and efficient solutions. One solution is to target specific observations for assimilation based on a sensitivity study or coupling strength analysis, because not all observations are equally effective in improving subsequent forecasts of hydrological variables, weather, agricultural production, or hazards through DA. This paper offers a perspective on current and future land DA development, and suggestions to optimally exploit advances in observing and modeling systems.
- Published
- 2022
- Full Text
- View/download PDF
7. Multi-Platform Radiometer Systems for Surface Soil Moisture Retrieval.
- Author
-
Xiaoling Wu 0001, Nan Ye, Jeffrey P. Walker, James Hills, François Jonard, and Valentijn R. N. Pauwels
- Published
- 2019
- Full Text
- View/download PDF
8. Sentinel-1 & Sentinel-2 for SOIL Moisture Retrieval at Field Scale.
- Author
-
Francesco Mattia, Anna Balenzano, Giuseppe Satalino, Francesco P. Lovergine, Jian Peng 0006, Urs Wegmüller, Oliver Cartus, Malcolm W. J. Davidson, Seung-Bum Kim, Joel T. Johnson, Jeffrey P. Walker, Xiaoling Wu 0001, Valentijn R. N. Pauwels, Heather McNairn, Thomas Caldwell, Michael H. Cosh, and Thomas J. Jackson
- Published
- 2018
- Full Text
- View/download PDF
9. River reconstruction using a conformal mapping method.
- Author
-
James E. Hilton, Stefania Grimaldi, Raymond C. Z. Cohen, Nikhil Garg, Yuan Li 0005, Steve P. Marvanek, Valentijn R. N. Pauwels, and Jeffrey P. Walker
- Published
- 2019
- Full Text
- View/download PDF
10. Assimilation of Wheat and Soil States into the APSIM-Wheat Crop Model: A Case Study.
- Author
-
Yuxi Zhang 0002, Jeffrey P. Walker, Valentijn R. N. Pauwels, and Yuval Sadeh
- Published
- 2022
- Full Text
- View/download PDF
11. Confirmation of vehicle stability criteria through a combination of smoothed particle hydrodynamics and laboratory measurements
- Author
-
Fatima Azhar, Valentijn R. N. Pauwels, and Ha H. Bui
- Subjects
Environmental Engineering ,Geography, Planning and Development ,Safety, Risk, Reliability and Quality ,Water Science and Technology - Published
- 2023
12. The 3114: A new professional helpline to swing the French suicide prevention in a new paradigm
- Author
-
C-E. Notredame, M. Wathelet, M. Morgiève, P. Grandgenèvre, C. Debien, C. Mannoni, N. Pauwels, F. Ducrocq, E. Leaune, P. Binder, S. Berrouiguet, M. Walter, P. Courtet, G. Vaiva, P. Thomas, CHU Lille, Lille Neurosciences & Cognition - U 1172 (LilNCog), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Lille-Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Centre National de Ressources et de Résilience [Lille] (CN2R), Centre Hospitalier Régional Universitaire [Lille] (CHRU Lille), Fédération régionale de la recherche en psychiatrie et santé mentale Hauts-de-France [Lille] ( F2RSM Psy), Centre Emma Ventura [CHU de la Martinique] (CEV [Fort de France]), CHU de la Martinique [Fort de France], Centre Hospitalier le Vinatier [Bron], Réseau des médecins ADOC Association RELAIS.17 (ADOC), Observatoire Régional de la Santé Poitou-Charentes (ORS Poitou-Charentes), Laboratoire de Traitement de l'Information Medicale (LaTIM), Université de Brest (UBO)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre Hospitalier Régional Universitaire de Brest (CHRU Brest)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Institut Brestois Santé Agro Matière (IBSAM), Université de Brest (UBO), CHRU Brest - Psychiatrie Adulte (CHU - Brest- Psychiatrie), Centre Hospitalier Régional Universitaire de Brest (CHRU Brest), Soins Primaires, Santé Publique, Registre des cancers de Bretagne Occidentale (EA7479 SPURBO), Université de Brest (UBO)-Centre Hospitalier Régional Universitaire de Brest (CHRU Brest)-Institut Brestois Santé Agro Matière (IBSAM), Université de Brest (UBO)-Université de Brest (UBO), Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier), Université de Montpellier (UM), Laboratoire de Neurosciences Fonctionnelles et Pathologies (LNFP), Université de Lille, Droit et Santé-Centre National de la Recherche Scientifique (CNRS), Axe 3 : organisation structurale multiéchelle des matériaux (SPCTS-AXE3), Science des Procédés Céramiques et de Traitements de Surface (SPCTS), Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Limoges (UNILIM)-Ecole Nationale Supérieure de Céramique Industrielle (ENSCI)-Institut des Procédés Appliqués aux Matériaux (IPAM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), CERMES3 - Centre de recherche Médecine, sciences, santé, santé mentale, société (CERMES3 - UMR 8211 / U988 / UM 7), École des hautes études en sciences sociales (EHESS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université de Poitiers, Institut de Génomique Fonctionnelle (IGF), and Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)
- Subjects
Psychiatry and Mental health ,[SDV]Life Sciences [q-bio] ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,[SDV.MHEP]Life Sciences [q-bio]/Human health and pathology ,[SHS]Humanities and Social Sciences - Abstract
International audience; Helpline services have been identified as an important component of suicide prevention strategies. While the Covid-19 pandemic have raised major concerns about severe and longstanding mental health consequences, the French ministry of Health has recently decidedto implement a national professional helpline dedicated to suicide prevention. The 3114 has been launched on the 1st of October 2021. Accessible 24/7 from any point of the national territory, it offers remote assistance to individuals in distress or worried for a close one,professionals and bereaved persons. Spread in regional call centers, medically supervised nurses and psychologists provide callers with listening, evaluation, intervention (including possible dispatch of a rescue team) and, whenever needed, referral to adapted services. At the same time, the “3114 centers” contribute to the implementation of the regional suicide prevention strategies by stimulating the development of actions, promoting resources, monitoring at-risk events, and collaborating with professional and associative stakeholders. From a public health perspective, the inception of the 3114 has settled the conditions for a new paradigm in the French suicide prevention strategy. By dedicating specific resources to promote and organize interactions between stakeholders, it supports a major shift from the juxtaposition of efficient but segregated actions to the creation of an integrated prevention system. Embedded to the project, multidisciplinary and multilevel research will be carried out to evaluate the implementation, impact, and transferability of the 3114 model, conceived both as a helpline and territorial prevention strategy.
- Published
- 2022
13. Copula-Based Downscaling of Coarse-Scale Soil Moisture Observations With Implicit Bias Correction.
- Author
-
Niko E. C. Verhoest, Martinus Johannes van den Berg, Brecht Martens, Hans Lievens, Eric F. Wood, Ming Pan, Yann H. Kerr, Ahmad Al Bitar, Sat Kumar Tomer, Matthias Drusch, Hilde Vernieuwe, Bernard De Baets, Jeffrey P. Walker, Gift Dumedah, and Valentijn R. N. Pauwels
- Published
- 2015
- Full Text
- View/download PDF
14. SMOSAR algorithm for soil moisture retrieval using Sentinel-1 data.
- Author
-
Anna Balenzano, Francesco Mattia, Giuseppe Satalino, Valentijn R. N. Pauwels, and Paul Snoeij
- Published
- 2012
- Full Text
- View/download PDF
15. Soil moisture retrieval from dense temporal series of C-band SAR data over agricultural sites.
- Author
-
Anna Balenzano, Giuseppe Satalino, Valentijn R. N. Pauwels, and Francesco Mattia
- Published
- 2011
- Full Text
- View/download PDF
16. Informing hydrogeological models with remotely sensed evapotranspiration
- Author
-
Simone Gelsinari, Tanya M. Doody, Sally E. Thompson, Rebecca Doble, Edoardo Daly, and Valentijn R. N. Pauwels
- Subjects
Water Science and Technology - Abstract
Remotely sensed evapotranspiration (ET) rates can provide an additional constraint on the calibration of groundwater models beyond typically-used water table (WT) level observations. The value of this constraint, measured in terms of reductions in model error, however, is expected to vary with the method by which it is imposed and by how closely the ET flux is dependant to groundwater levels. To investigate this variability, four silvicultural sites with different access to groundwater were modeled under three different model-data configurations. A benchmark model that used only WT levels for calibration was compared to two alternatives: one in which satellite remotely sensed ET rates from MODIS-CMRSET were also included in model calibration, and one in which the satellite ET data were assimilated, through the Ensemble Kalman Filter, into the model. Large error reductions in ET flux outputs were achieved when CMRSET data were used to calibrate the model. Assimilation of CMRSET data further improved the model performance statistics where the WT was < 6.5 m deep. It is advantageous to use spatially distributed actual ET data to calibrate groundwater models where it is available. In situations where vegetation has direct access to groundwater, assimilation of ET observations is likely to improve model performance.
- Published
- 2022
- Full Text
- View/download PDF
17. Probabilistic Attenuation Nowcasting for the 5G Telecommunication Networks
- Author
-
Valentijn R. N. Pauwels, Adrien Guyot, Jayaram Pudashine, Alan Seed, Carlos Velasco-Forero, Mark Curtis, and Jeffrey P. Walker
- Subjects
Nowcasting ,Computer science ,business.industry ,Attenuation ,Probabilistic logic ,Weather forecasting ,020206 networking & telecommunications ,02 engineering and technology ,computer.software_genre ,law.invention ,law ,0202 electrical engineering, electronic engineering, information engineering ,Weather radar ,Electrical and Electronic Engineering ,Radar ,Telecommunications ,business ,computer ,Physics::Atmospheric and Oceanic Physics ,Lead time ,Confidence region - Abstract
In this letter, we propose a novel approach to produce attenuation forecasts for microwave links using a probabilistic approach. It uses ensembles of forecast rainfall fields to easily derive attenuation forecasts for specific frequencies. The proposed approach uses the short-term ensemble prediction system (STEPS) to generate ensembles of high, spatial and temporal, resolution forecast rainfall fields based on observed weather radar fields with lead times of 15–90 min. Attenuation forecasts could eventually be used by telecommunication operators to drive the operation of wireless networks and ensure their maintenance during severe and extreme rainfall events. This study used 109 microwave links ranging from 15 to 40 GHz to verify the results of this probabilistic attenuation forecast. Results suggest that the STEPS-based attenuation forecasts were within the narrow span of the 90% confidence region for all microwave links tested up to 30 min lead time, decreasing for longer lead times. Examples of how the proposed approach can be used to derive a detailed probabilistic attenuation forecast for multiple lead times within a domain of few kilometers, as well as probability of attenuation maps for large areas are shown.
- Published
- 2021
18. Unsaturated zone model complexity for the assimilation of evapotranspiration rates in groundwater modelling
- Author
-
Simone Gelsinari, Nicholas Fewster-Young, Edoardo Daly, Jos van Dam, Rebecca Doble, Valentijn R. N. Pauwels, Remko Uijlenhoet, Gelsinari, Simone, Pauwels, Valentijn R.N., Daly, Edoardo, Van Dam, Jos, Uijlenhoet, Remko, Fewster-Young, Nicholas, and Doble, Rebecca
- Subjects
Technology ,010504 meteorology & atmospheric sciences ,Water table ,0208 environmental biotechnology ,Soil science ,02 engineering and technology ,Hydrology and Quantitative Water Management ,Environmental technology. Sanitary engineering ,unsaturated zone ,01 natural sciences ,Data assimilation ,Evapotranspiration ,groundwater ,Vadose zone ,Geography. Anthropology. Recreation ,Life Science ,GE1-350 ,biophysical processes ,TD1-1066 ,0105 earth and related environmental sciences ,WIMEK ,Water transport ,evapotranspiration-water table dynamics ,Groundwater recharge ,Bodemfysica en Landbeheer ,020801 environmental engineering ,Environmental sciences ,Soil Physics and Land Management ,Environmental science ,Groundwater model ,Groundwater ,Hydrologie en Kwantitatief Waterbeheer - Abstract
The biophysical processes occurring in the unsaturated zone have a direct impact on the water table dynamics. Representing these processes through the application of unsaturated zone models of different complexity has an impact on the estimates of the volumes of water flowing between the unsaturated zone and the aquifer. These fluxes, known as net recharge, are often used as the shared variable that couples unsaturated to groundwater models. However, as recharge estimates are always affected by a degree of uncertainty, model–data fusion methods, such as data assimilation, can be used to inform these coupled models and reduce uncertainty. This study assesses the effect of unsaturated zone models complexity (conceptual versus physically based) to update groundwater model outputs, through the assimilation of actual evapotranspiration rates, for a water-limited site in South Australia. Actual evapotranspiration rates are assimilated because they have been shown to be related to the water table dynamics and thus form the link between remote sensing data and the deeper parts of the soil profile. Results have been quantified using standard metrics, such as the root mean square error and Pearson correlation coefficient, and reinforced by calculating the continuous ranked probability score, which is specifically designed to determine a more representative error in stochastic models. It has been found that, once properly calibrated to reproduce the actual evapotranspiration–water table dynamics, a simple conceptual model may be sufficient for this purpose; thus using one configuration over the other should be motivated by the specific purpose of the simulation and the information available.
- Published
- 2021
19. Fuzzy Models of Rainfall-Discharge Dynamics.
- Author
-
Hilde Vernieuwe, Olga Georgieva, Bernard De Baets, Valentijn R. N. Pauwels, and Niko E. C. Verhoest
- Published
- 2003
- Full Text
- View/download PDF
20. Tree hydrodynamic modelling of the soil–plant–atmosphere continuum using FETCH3
- Author
-
Marcela Silva, Ashley M. Matheny, Valentijn R. N. Pauwels, Dimetre Triadis, Justine E. Missik, Gil Bohrer, and Edoardo Daly
- Subjects
Physics::Atmospheric and Oceanic Physics - Abstract
Modelling the water transport along the soil–plant–atmosphere continuum is fundamental to estimating and predicting transpiration fluxes. A Finite-difference Ecosystem-scale Tree Crown Hydrodynamics model (FETCH3) for the water fluxes across the soil–plant–atmosphere continuum is presented here. The model combines the water transport pathways into one vertical dimension, and assumes that the water flow through the soil, roots, and above-ground xylem can be approximated as flow in porous media. This results in a system of three partial differential equations, resembling the Richardson–Richards equation, describing the transport of water through the plant system and with additional terms representing sinks and sources for the transfer of water from the soil to the roots and from the leaves to the atmosphere. The numerical scheme, developed in Python 3, was tested against exact analytical solutions for steady state and transient conditions using simplified but realistic model parameterizations. The model was also used to simulate a previously published case study, where observed transpiration rates were available, to evaluate model performance. With the same model setup as the published case study, FETCH3 results were in agreement with observations. Through a rigorous coupling of soil, root xylem, and stem xylem, FETCH3 can account for variable water capacitance, while conserving mass and the continuity of the water potential between these three layers. FETCH3 provides a ready-to-use open access numerical model for the simulation of water fluxes across the soil–plant–atmosphere continuum.
- Published
- 2022
21. Multivariate and Multiscale Data Assimilation in Terrestrial Systems: A Review.
- Author
-
Carsten Montzka, Valentijn R. N. Pauwels, Harrie-Jan Hendricks-Franssen, Xujun Han, and Harry Vereecken
- Published
- 2012
- Full Text
- View/download PDF
22. Crop Classification Using Short-Revisit Multitemporal SAR Data.
- Author
-
Henning Skriver, Francesco Mattia, Giuseppe Satalino, Anna Balenzano, Valentijn R. N. Pauwels, Niko E. C. Verhoest, and Malcolm Davidson
- Published
- 2011
- Full Text
- View/download PDF
23. Estimation of the Spatially Distributed Surface Energy Budget for AgriSAR 2006, Part II: Integration of Remote Sensing and Hydrologic Modeling.
- Author
-
Els De Lathauwer, Wim J. Timmermans, Giuseppe Satalino, Francesco Mattia, Alexander Loew, Juan Carlos Jiménez-Muñoz, Victoria Hidalgo, José A. Sobrino, and Valentijn R. N. Pauwels
- Published
- 2011
- Full Text
- View/download PDF
24. Estimation of the Spatially Distributed Surface Energy Budget for AgriSAR 2006, Part I: Remote Sensing Model Intercomparison.
- Author
-
Wim J. Timmermans, Juan Carlos Jiménez-Muñoz, Victoria Hidalgo, Katja Richter, José A. Sobrino, Guido D'Urso, Giuseppe Satalino, Francesco Mattia, Els De Lathauwer, and Valentijn R. N. Pauwels
- Published
- 2011
- Full Text
- View/download PDF
25. Optimization of Soil Hydraulic Model Parameters Using Synthetic Aperture Radar Data: An Integrated Multidisciplinary Approach.
- Author
-
Valentijn R. N. Pauwels, Anna Balenzano, Giuseppe Satalino, Henning Skriver, Niko E. C. Verhoest, and Francesco Mattia
- Published
- 2009
- Full Text
- View/download PDF
26. The role of neuromodulation in chronic functional constipation: a systematic review
- Author
-
N Pauwels, S Hellemans, J Roenen, H. U. De Schepper, C Willemse, T Van Aggelpoel, S. Van den Broeck, and Niels Komen
- Subjects
Adult ,medicine.medical_specialty ,Constipation ,medicine.medical_treatment ,Transcutaneous electrical nerve stimulation ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,Randomized controlled trial ,law ,medicine ,Humans ,Percutaneous tibial nerve stimulation ,Neurostimulation ,Randomized Controlled Trials as Topic ,Modalities ,business.industry ,Sacrococcygeal Region ,medicine.disease ,Neuromodulation (medicine) ,030220 oncology & carcinogenesis ,Functional constipation ,030211 gastroenterology & hepatology ,Human medicine ,medicine.symptom ,business - Abstract
Background : Chronic functional constipation is a highly prevalent disorder in which, when conservative measures fail to relieve symptoms, surgical interventions are sometimes indicated. In recent years, neuromodulation for the treatment of functional constipation has gained interest but its role and effectiveness are still unclear. The purpose of this review is to provide a systematic overview on the current literature on the different modalities of neurostimulation and their effect on chronic functional constipation in adults as reported in the literature. Methods : A search in the literature for articles concerning the effect of different types of neuromodulation on constipation was performed in PubMed using extensive search terms for the different modalities of neuromodulation. Studies and trials were checked for eligibility. For all types of neuromodulation together, 27 articles were included. Results : 17 studies were included on SNM (sacral nerve modulation). Although multiple studies show positive results on the effect of SNM in constipation, double-blind crossover RCT’s (randomised controlled trials) showed no significant effect. 3 studies were included for tSNS (transcutaneous sacral nerve stimulation), 2 for PTNS (percutaneous tibial nerve stimulation) and 2 for TTNS (transcutaneous tibial nerve stimulation). Studies and trials on these modalities of neuromodulation reported ambiguous results on statistical significance of the effect. For transcutaneous IFC (interferential current therapy) 2 studies were included, which both reported a statistically significant effect on all outcomes. Conclusion : The beneficial effect of neuromodulation in chronic functional constipation remains questionable. However, neuro-modulation might be worth considering in patients refractory to treatment before turning to more invasive measures. Future research should shed more light on the effects of neuromodulation in constipation.
- Published
- 2021
27. Tree Hydrodynamic Modelling of Soil Plant Atmosphere Continuum (SPAC-3Hpy)
- Author
-
Justine E. Missik, Ashley M. Matheny, Marcela Silva, Gil Bohrer, Edoardo Daly, Dimetre Triadis, and Valentijn R. N. Pauwels
- Subjects
Soil plant atmosphere continuum ,Partial differential equation ,Water transport ,Steady state ,Water flow ,Flow (psychology) ,Environmental science ,Mechanics ,Porous medium ,Transpiration - Abstract
Modelling the water transport along the soil-plant-atmosphere continuum is fundamental to estimating and predicting transpiration fluxes. A tree-hydrodynamic model (SPAC-3Hpy) for the water fluxes across the soil-plant-atmosphere continuum is presented here. The model combines the water transport pathways to one vertical dimension, and assumes that the water flow through the soil, roots, and above-ground xylem can be approximated as a flow in porous media. This results in a system of three partial differential equations resembling the Richardson-Richards equation describing the transport of water through the plant system and with additional terms representing sinks and sources for the transfer of water from to the soil to the roots and from the leaves to the atmosphere. The numerical scheme, developed in Python 3, was tested against exact analytical solutions for steady state and transient conditions using simplified but realistic model parametrizations. The model was also used to simulate a previously published case study where observed transpiration rates were available in order to evaluate model performance. With the same model setup as the published case study, SPAC-3Hpy results were in agreement with observations. Through a rigorous coupling of soil, roots, and hydroactive xylem, SPAC-3Hpy can account for variable capacitance while conserving mass and the continuity of the water potential between these three layers. SPAC-3Hpy provides a ready-to-use open access numerical model for the simulation of water fluxes across the soil-plant-atmosphere continuum.
- Published
- 2021
28. Supplementary material to 'Tree Hydrodynamic Modelling of Soil Plant Atmosphere Continuum (SPAC-3Hpy)'
- Author
-
Marcela Silva, Ashley M. Matheny, Valentijn R. N. Pauwels, Dimetre Triadis, Justine E. Missik, Gil Bohrer, and Edoardo Daly
- Published
- 2021
29. Reanalysis in Earth System Science: Toward Terrestrial Ecosystem Reanalysis
- Author
-
H. Beck, Michael Dietze, Debjani Sihi, Heye Bogena, Angela Lausch, Ann Raiho, Umakant Mishra, Katja Fennel, Yijian Zeng, E. Euskirchen, Harrie-Jan Hendricks Franssen, Mathew Williams, M. Mirtl, Stefano Ciavatta, Valentijn R. N. Pauwels, M. Adamescu, Luis Samaniego, Bibi S. Naz, K. Van Looy, C. Poppe, G. De Lannoy, Andrew M. Fox, Carsten Montzka, Harry Vereecken, Roland Baatz, Steffen Zacharias, Klaus Goergen, Hendricks Franssen, H. J., 1 Agrosphere Institute of Bio and Geosciences Forschungszentrum Jülich Jülich Germany, Euskirchen, E., 3 University of Alaska Fairbanks Institute of Arctic Biology Fairbanks AK USA, Sihi, D., 4 Department of Environmental Sciences Emory University Atlanta GA USA, Dietze, M., 5 Earth and Environment Boston University Boston MA USA, Ciavatta, S., 6 Plymouth Marine Laboratory Plymouth UK, Fennel, K., 8 Department of Oceanography Dalhousie University Halifax NS Canada, Beck, H., 9 Department of Civil and Environmental Engineering Princeton University Princeton NJ USA, De Lannoy, G., 10 Department of Earth and Environmental Sciences KU Leuven Heverlee Belgium, Pauwels, V. R. N., 11 Department of Civil Engineering Monash University Clayton VIC Australia, Raiho, A., 12 Fish, Wildlife, and Conservation Department Colorado State University Fort Collins CO USA, Montzka, C., Williams, M., 13 School of GeoSciences and NCEO University of Edinburgh Edinburgh UK, Mishra, U., 14 Bioscience Division Sandia National Laboratory Livermore CA USA, Poppe, C., Zacharias, S., 15 Department of Monitoring and Exploration Technologies UFZ Helmholtz Centre for Environmental Research Leipzig Germany, Lausch, A., 16 Department Computational Landscape Ecology Helmholtz Centre for Environmental Research–UFZ Leipzig Germany, Samaniego, L., 18 Department Computational Hydrosystems Helmholtz Centre for Environmental Research ‐ UFZ Leipzig Germany, Van Looy, K., 19 OVAM, International Policy Unit Mechelen Belgium, Bogena, H., Adamescu, M., 20 Research Center for Systems Ecology and Sustainability University of Bucharest Bucharest Romania, Mirtl, M., Fox, A., 21 Joint Center for Satellite Data Assimilation UCAR Boulder CO USA, Goergen, K., Naz, B. S., Zeng, Y., 23 Faculty of Geo‐information Science and Earth Observation (ITC) University of Twente Enschede The Netherlands, Vereecken, H., Department of Water Resources, Digital Society Institute, UT-I-ITC-WCC, and Faculty of Geo-Information Science and Earth Observation
- Subjects
Geochemistry & Geophysics ,ecosystem reanalysis ,010504 meteorology & atmospheric sciences ,land surface reanalysis ,0207 environmental engineering ,reanalysis ,HYDROLOGIC DATA ASSIMILATION ,02 engineering and technology ,WATER STORAGE ,SOIL-MOISTURE ,01 natural sciences ,ITC-HYBRID ,hydrologic reanalysis ,Data assimilation ,LAND-SURFACE MODEL ,ENSEMBLE KALMAN FILTER ,ddc:550 ,SEQUENTIAL MONTE-CARLO ,020701 environmental engineering ,data assimilation ,0105 earth and related environmental sciences ,Science & Technology ,carbon cycle reanalysis ,LEAF-AREA INDEX ,SPECIES DISTRIBUTION MODELS ,15. Life on land ,550 Geowissenschaften ,Earth system science ,Geophysics ,13. Climate action ,Climatology ,ITC-ISI-JOURNAL-ARTICLE ,Physical Sciences ,Environmental science ,Terrestrial ecosystem ,CARBON-CYCLE ,GLOBAL GRIDDED SYNTHESIS - Abstract
A reanalysis is a physically consistent set of optimally merged simulated model states and historical observational data, using data assimilation. High computational costs for modeled processes and assimilation algorithms has led to Earth system specific reanalysis products for the atmosphere, the ocean and the land separately. Recent developments include the advanced uncertainty quantification and the generation of biogeochemical reanalysis for land and ocean. Here, we review atmospheric and oceanic reanalyzes, and more in detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Although a future joint reanalysis of land surface, hydrologic, and carbon processes represents an analysis of important ecosystem variables, biotic ecosystem variables are assimilated only to a very limited extent. Continuous data sets of ecosystem variables are needed to explore biotic‐abiotic interactions and the response of ecosystems to global change. Based on the review of existing achievements, we identify five major steps required to develop terrestrial ecosystem reanalysis to deliver continuous data streams on ecosystem dynamics., Plain Language Summary: A reanalysis is a unique set of continuous variables produced by optimally merging a numerical model and observed data. The data are merged with the model using available uncertainty estimates to generate the best possible estimate of the target variables. The framework for generating a reanalysis consists of the model, the data, and the model‐data‐fusion algorithm. The very specific requirements of reanalysis frameworks have led to the development of Earth‐compartment specific reanalysis for the atmosphere, the ocean and land. Here, we review atmospheric and oceanic reanalyzes, and in more detail biogeochemical ocean and terrestrial reanalyzes. In particular, we identify land surface, hydrologic, and carbon cycle reanalyzes which are nowadays produced in targeted projects for very specific purposes. Based on a review of existing achievements, we identify five major steps required to develop reanalysis for terrestrial ecosystem to shed more light on biotic and abiotic interactions. In the future, terrestrial ecosystem reanalysis will deliver continuous data streams on the state and the development of terrestrial ecosystems., Key Points: Reanalyzes provide decades‐long model‐data‐driven harmonized and continuous data sets for new scientific discoveries. Novel global scale reanalyzes quantify the biogeochemical ocean cycle, terrestrial carbon cycle, land surface, and hydrologic processes. New observation technology and modeling capabilities allow in the near future production of advanced terrestrial ecosystem reanalysis., European Union's Horizon 2020 research and innovation programme, Deutsche Forschungsgemeinschaft, U.S. Department of Energy, Emory University's Halle Institute for Global Research and the Halle Foundation Collaborative Research, NSF, NASA, Natural Environment Research Council, European Union'’s Horizon 2020 research and innovation programme, NSERC Discovery program, the Ocean Frontier Institute, and MEOPAR, Research Foundation Flanders (FWO), Helmholtz Association, NASA Terrestrial Ecosystems
- Published
- 2021
30. River reconstruction using a conformal mapping method
- Author
-
Stefania Grimaldi, Steve Marvanek, Valentijn R. N. Pauwels, Raymond C.Z. Cohen, Yuan Li, James E. Hilton, Nikhil Garg, and Jeffrey P. Walker
- Subjects
Environmental Engineering ,Data collection ,010504 meteorology & atmospheric sciences ,Ecological Modeling ,0208 environmental biotechnology ,Conformal map ,02 engineering and technology ,01 natural sciences ,020801 environmental engineering ,Multivariate interpolation ,Spline (mathematics) ,Discrete points ,Kriging ,Bathymetry ,Algorithm ,Software ,Hydrodynamic flow ,Geology ,0105 earth and related environmental sciences - Abstract
Accurate river bathymetry is required for applications including hydrodynamic flow modelling and understanding morphological processes. Bathymetric measurements are typically a set of depths at discrete points that must be reconstructed into a continuous surface. A number of algorithms exist for this reconstruction, including spline-based techniques and kriging methods. A novel and efficient method is introduced to produce a co-ordinate system fitted to the river path suitable for bathymetric reconstructions. The method is based on numerical conformal mapping and can handle topological features such as islands and branches in the river. Bathymetric surfaces generated using interpolation over a conformal map are compared to spline-based and kriging methods on a section of the Balonne River, Australia. The results show that the conformal mapping algorithm produces reconstructions comparable in quality to existing methods, preserves flow-wise features and is relatively insensitive to the number of sample points, enabling faster data collection in the field.
- Published
- 2019
31. Challenges, Opportunities, and Pitfalls for Global Coupled Hydrologic‐Hydraulic Modeling of Floods
- Author
-
Valentijn R. N. Pauwels, Guy Schumann, Stefania Grimaldi, Jeffrey P. Walker, and Ashkan Shokri
- Subjects
Hydraulic engineering ,Environmental science ,Civil engineering ,Water Science and Technology - Published
- 2019
32. Performance of Different Ensemble Kalman Filter Structures to Assimilate GRACE Terrestrial Water Storage Estimates Into a High‐Resolution Hydrological Model: A Synthetic Study
- Author
-
Albert van Dijk, Valentijn R. N. Pauwels, Jeffrey P. Walker, and Ashkan Shokri
- Subjects
TWS ,010504 meteorology & atmospheric sciences ,0208 environmental biotechnology ,Resolution (electron density) ,02 engineering and technology ,01 natural sciences ,hydrological modeling ,020801 environmental engineering ,Scholarship ,GRACE ,Ensemble Kalman filter ,Postgraduate research ,EnKF ,Geology ,Terrestrial water storage ,0105 earth and related environmental sciences ,Water Science and Technology ,Remote sensing - Abstract
Among all remote sensing missions, the Gravity Recovery and Climate Experiment (GRACE) was unique as it measured the change in total water content across all terrestrial water storages (TWS) including subsurface, deep soil moisture, and groundwater. However, its coarse resolution is a major challenge for practical applications. Ensemble Kalman filters (EnKFs) are useful tools to combine observations with models to reduce prediction errors. But due to the coarse resolution of the GRACE products, the EnKF does not work well in its usual form. Accordingly, different EnKF structures have been proposed and employed but a comparison between them has not yet been attempted. Here we assessed these structures using a synthetic problem. Alternative structures were formed using different increment calculation and updating strategies, observation operators, and the types of observation fed to the filter. It was found that all available structures led to an improvement in model performance when measured against a synthetic reference. However, the degree of improvement was strongly dependent on the assimilation strategy. Assimilating absolute TWS values (the summation of the TWS anomalies and an unbiased baseline) gave the best model performance when combined with an increment calculation strategy in which the increments are calculated and applied to all days of the month. However, without an unbiased baseline, assimilating TWS changes still leads to an acceptable improvement in model performance. Among the observation operators, those that predict the observations as an average of multiple days had the best performance.
- Published
- 2018
33. On the Impacts of Observation Location, Timing, and Frequency on Flood Extent Assimilation Performance
- Author
-
Guy Schumann, Stefania Grimaldi, Raaj Ramsankaran, Jeffrey P. Walker, Valentijn R. N. Pauwels, Renaud Hostache, and Antara Dasgupta
- Subjects
Synthetic aperture radar ,Data assimilation ,Meteorology ,Flood myth ,Hydraulic engineering ,Flood forecasting ,Environmental science ,Assimilation (biology) ,Particle filter ,Water Science and Technology - Published
- 2021
34. A Mutual Information‐Based Likelihood Function for Particle Filter Flood Extent Assimilation
- Author
-
Raaj Ramsankaran, Guy Schumann, Antara Dasgupta, Valentijn R. N. Pauwels, Jeffrey P. Walker, Stefania Grimaldi, and Renaud Hostache
- Subjects
Synthetic aperture radar ,Data assimilation ,Flood myth ,Meteorology ,Computer science ,Flood forecasting ,Assimilation (biology) ,Mutual information ,Likelihood function ,Particle filter ,Water Science and Technology - Published
- 2021
35. Earth Observation and Hydraulic Data Assimilation for Improved Flood Inundation Forecasting
- Author
-
Marco Chini, Raaj Ramsankaran, Patrick Matgen, Jeffrey P. Walker, Antara Dasgupta, Stefania Grimaldi, Renaud Hostache, and Valentijn R. N. Pauwels
- Subjects
Current (stream) ,Earth observation ,geography ,Data assimilation ,geography.geographical_feature_category ,Flood myth ,Meteorology ,Floodplain ,Flood forecasting ,Environmental science ,Field (computer science) ,Boundary (real estate) - Abstract
Accurately simulating floodplain inundation is absolutely vital to minimize damage to life and property. The giant strides made in advanced computing, now allow running increasingly complex models at reasonable resolutions over large areas, with the promise of further improvement in the near future. However, the uncertainty contributed by input, boundary, and forcing data, often leads to highly erroneous predictions. As spatially distributed Earth Observations of flood extent and water level become increasingly available, they pave the way for further constraining, and hence, improving the accuracy of hydraulic flood forecasting models. Effectively using these datasets requires an in-depth understanding of the impacts that the resolution, accuracy, location, timing, and frequency of acquisition of observations may have on model-data integration efforts. This chapter presents a review of the current capabilities in the field of flood data assimilation. The challenges and opportunities of using Earth Observation data for operational flood inundation forecasting are also discussed.
- Published
- 2021
36. Wildfire Smoke Particulate Matter Concentration Measurements Using Radio Links From Cellular Communication Networks
- Author
-
Alain Protat, Valentijn R. N. Pauwels, Adrien Guyot, Remko Uijlenhoet, Valentin Louf, Jeffrey P. Walker, and Jayaram Pudashine
- Subjects
Smoke ,Atmospheric sounding ,WIMEK ,Planetary boundary layer ,Radio Link Protocol ,Humidity ,General Medicine ,Anomalous propagation ,Particulates ,Hydrology and Quantitative Water Management ,Atmospheric sciences ,law.invention ,law ,Life Science ,Environmental science ,Air quality index ,Hydrologie en Kwantitatief Waterbeheer - Abstract
The monitoring of wildfire smoke is important to help mitigate impacts on people such as by sending early warnings to affected areas. Received signal levels (RSLs) from radio links have been used as an opportunistic way to accurately measure rainfall and humidity. Radio links provide integrated measurements along their paths and are an exceptional untapped resource to complement air quality stations in areas affected by smoke events, or in developing countries without air quality monitoring capability. This study analyzed radio link signal fluctuations during smoke events associated with the 2019–2020 Australian wildfires. Concurrently, the atmospheric boundary layer was characterized using atmospheric soundings and surface observations, as well as air quality proxies such as particulate matter concentrations less than 2.5 μm (10 μm), or PM2.5 (PM10). Observations showed that dry air containing large amounts of smoke within a surface layer above the ground acted as a lid, reducing dispersion, trapping and maintaining high ground-level concentrations of smoke. These conditions also created anomalous propagation conditions for radio links and operational weather radars. Power-law relations between signal fluctuations and PM10 and PM2.5 were derived based on the link data collected and the closest air quality station observations. While there was variability in retrieval performance across smoke events, the best performance determination coefficients exceeded 0.5, with an RMSE on the order of less than 50 μg m−3 for concentrations of more than 400 μg m−3. Mid-range link lengths (5–20 km) provided the best results.
- Published
- 2021
37. Water balance estimation in Australia through the merging of satellite observations with models
- Author
-
Valentijn R. N. Pauwels, Ashkan Shokri, Ashley Wright, and Stefania Grimaldi
- Subjects
Estimation ,Water balance ,Flood myth ,Work (electrical) ,business.industry ,Satellite data ,Environmental resource management ,Environmental science ,Satellite ,business ,Surface water ,Merge (version control) - Abstract
Australia is the driest of all inhabited continents, and is prone to both droughts and severe floods. In order to mitigate the impact of these phenomena, accurate flood forecasts and a reliable estimate of the land surface water storage are needed. This chapter provides an overview of three studies developing innovative methods to merge satellite data with models to achieve these goals. The overall conclusion from this work is that satellite data provide extremely valuable information for an improved water management, and that innovative methods are required to fully utilize their potential.
- Published
- 2021
38. Rainfall retrieval using commercial microwave links : Effect of sampling strategy on retrieval accuracy
- Author
-
Jeffrey P. Walker, Valentijn R. N. Pauwels, Jayaram Pudashine, Alan Seed, Adrien Guyot, Mahesh Prakash, Aart Overeem, and Remko Uijlenhoet
- Subjects
Rainfall ,010504 meteorology & atmospheric sciences ,Mean squared error ,Cellular communication networks ,0207 environmental engineering ,02 engineering and technology ,Microwave links ,Hydrology and Quantitative Water Management ,01 natural sciences ,law.invention ,law ,Statistics ,Radar ,020701 environmental engineering ,0105 earth and related environmental sciences ,Water Science and Technology ,Mathematics ,WIMEK ,Sampling (statistics) ,Ranging ,Microwave transmission ,Remote sensing ,Matthews correlation coefficient ,Open source ,13. Climate action ,Opportunistic sensing ,Microwave ,Hydrologie en Kwantitatief Waterbeheer - Abstract
This study presents the first evaluation of using commercial microwave link (CML) data for rainfall measurements in Australia, with the test site being the greater Melbourne Metropolitan area. More than 100 CMLs with microwave frequency ranging between 10 and 40 GHz have been used for the rainfall retrieval. The 15-minute received signal levels (RSLs) for each CML based on two sampling strategies (average and minimum/maximum) collected for 2 years provided a unique dataset to compare performances of rainfall retrievals. The open source algorithm RAINLINK was used for deriving rainfall from the 15-minute RSL data. From two years of data, a subset of 30 rainy days distributed across this period were used for calibrating the RAINLINK parameters, with the remaining data used for validation. For this study, only path-averaged rainfall intensities were validated based on a gauge-adjusted radar product serving as the reference. The result of the wet-dry classification showed that the minimum and maximum RSL data performed better, with lower probability of false detection and higher Matthews correlation coefficient than average RSL data. For the rainfall retrieval, both datasets showed similar correlation with the gauge adjusted radar product. However, based on other statistics (RMSE, bias and CV) minimum and maximum RSL data outperformed average for the rainfall retrieval. Overall, this study highlights the robust accuracy of commercial microwave links for rainfall retrieval while using only minimum and maximum RSL data.
- Published
- 2021
39. Sentinel-1 soil moisture at 1 km resolution: a validation study
- Author
-
Yann Kerr, Heather McNairn, Francesco P. Lovergine, Giuseppe Satalino, Francesco Mattia, Jian Peng, Katarzyna Dąbrowska-Zielińska, Joel T. Johnson, Jeffrey P. Walker, Jan Pawel Musial, Thomas J. Jackson, Davide Palmisano, Oliver Cartus, Philip Marzahn, Dara Entekhabi, Malcolm Davidson, Urs Wegmüller, Simon Yueh, Michael H. Cosh, Valentijn R. N. Pauwels, and Anna Balenzano
- Subjects
Synthetic aperture radar ,010504 meteorology & atmospheric sciences ,Mean squared error ,0208 environmental biotechnology ,Soil Science ,02 engineering and technology ,01 natural sciences ,law.invention ,symbols.namesake ,law ,Linear regression ,Validation ,Range (statistics) ,Computers in Earth Sciences ,Radar ,Water content ,0105 earth and related environmental sciences ,Remote sensing ,Synthetic Aperture Radar (SAR) ,Geology ,Spatial representativeness error (SRE) ,Pearson product-moment correlation coefficient ,020801 environmental engineering ,Soil moisture High resolution ,symbols ,Environmental science ,Sentinel-1 ,Change detection - Abstract
This study presents an assessment of a pre-operational soil moisture product at 1 km resolution derived from satellite data acquired by the European Radar Observatory Sentinel-1 (S-1), representing the first space component of the Copernicus program. The product consists of an estimate of surface soil volumetric water content (SSM) [m/m] and its uncertainty [m/m], both at 1 km. The retrieval algorithm relies on a time series based Short Term Change Detection (STCD) approach, taking advantage of the frequent revisit of the S-1 constellation that performs C-band Synthetic Aperture Radar (SAR) imaging. The performance of the S-1 SSM product is estimated through a direct comparison between 1068 S-1 SSM images against in situ SSM measurements acquired by 167 ground stations located in Europe, America and Australia, over 4 years between January 2015 and December 2020, depending on the site. The paper develops a method to estimate the spatial representativeness error (SRE) that arises from the mismatch between the S-1 SSM retrieved at 1 km resolution and the in situ point-scale SSM observations. The impact of SRE on standard validation metrics, i.e., root mean square error (RMSE), Pearson correlation (R) and linear regression, is quantified and experimentally assessed using S-1 and ground SSM data collected over a dense hydrologic network (4 - 5 stations/km) located in the Apulian Tavoliere (Southern Italy). Results show that for the dense hydrological network the RMSE and correlation are ~0.06 m/m and 0.71, respectively, whereas for the sparse hydrological networks, i.e., 1 station/km, the SRE increases the RMSE by ~0.02 m/m (70% Confidence Level). Globally, the S-1 SSM product is characterized by an intrinsic (i.e., with SRE removed) RMSE of ~0.07 m/m over the SSM range [0.03, 0.60] m/m and R of 0.54. A breakdown of the RMSE per dry, medium and wet SSM ranges is also derived and its implications for setting realistic requirements for SAR-based SSM retrieval are discussed together with recommendations for the density of in situ SSM observations.
- Published
- 2021
40. PE-23: Reversal of Treatment-refractory Malabsorption after Resection of Jejunal Diverticulosis: A Case Series
- Author
-
L, Wauters, primary, M, Clarysse, additional, I, Jochmans, additional, D, Monbaliu, additional, L, Ceulemans, additional, A, Verbiest, additional, M, Miserez, additional, N, Lauwers, additional, W, Nys, additional, N, Pauwels, additional, M, Hiele, additional, J, Pirenne, additional, and T, Vanuytsel, additional
- Published
- 2021
- Full Text
- View/download PDF
41. PE-25: Significant Improvement in Catheter Related Infections, Hospitalization Duration and Self-care after the Implementation of a Multidisciplinary Approach in Intestinal Failure
- Author
-
N, Lauwers, primary, N, Pauwels, additional, W, Nys, additional, J, Vanderstappen, additional, M, Pijpops, additional, L, Wauters, additional, M, Hiele, additional, N, Moerman, additional, K, Cosaert, additional, P, Declercq, additional, M, Jerome, additional, K, Geboers, additional, A, Verbiest, additional, and T, Vanuytsel, additional
- Published
- 2021
- Full Text
- View/download PDF
42. Application of Remote Sensing Data to Constrain Operational Rainfall-Driven Flood Forecasting: A Review.
- Author
-
Yuan Li 0005, Stefania Grimaldi, Jeffrey P. Walker, and Valentijn R. N. Pauwels
- Published
- 2016
- Full Text
- View/download PDF
43. The evolution of process-based hydrologic models: Historical challenges and the collective quest for physical realism
- Author
-
Martyn P. Clark, Andrew W. Wood, Marc F. P. Bierkens, Xitian Cai, Valentijn R. N. Pauwels, Remko Uijlenhoet, Christa D. Peters-Lidard, Ross Woods, Katrina E. Bennett, and Luis Samaniego
- Subjects
Environmental Engineering ,010504 meteorology & atmospheric sciences ,Computer science ,Process (engineering) ,Hydrological modelling ,0208 environmental biotechnology ,Model parameters ,02 engineering and technology ,Hydrology and Quantitative Water Management ,Civil Engineering ,01 natural sciences ,lcsh:Technology ,Physical Geography and Environmental Geoscience ,lcsh:TD1-1066 ,Article ,Life Science ,lcsh:Environmental technology. Sanitary engineering ,Process engineering ,Data limitations ,lcsh:Environmental sciences ,0105 earth and related environmental sciences ,lcsh:GE1-350 ,WIMEK ,Management science ,lcsh:T ,business.industry ,lcsh:Geography. Anthropology. Recreation ,Research needs ,020801 environmental engineering ,lcsh:G ,Key (cryptography) ,Environmental science ,business ,Realism ,Diversity (business) ,Hydrologie en Kwantitatief Waterbeheer - Abstract
The diversity in hydrologic models has historically led to great controversy on the “correct” approach to process-based hydrologic modeling, with debates centered on the adequacy of process parameterizations, data limitations and uncertainty, and computational constraints on model analysis. In this paper we revisit key modeling challenges, outlined by Freeze and Harlan nearly 50 years ago, on requirements to (1) define suitable model equations, (2) define adequate model parameters, and (3) cope with limitations in computing power. We outline the historical modeling challenges, summarize modeling advances that address these challenges, and define outstanding research needs. We illustrate how modeling advances have been made by groups using models of different type and complexity, and we argue for the need to more effectively use our diversity of modeling approaches in order to advance our collective quest for physically realistic hydrologic models.
- Published
- 2020
44. Unsaturated zone model complexity for the assimilation of evapotranspiration rates in groundwater modeling
- Author
-
Simone Gelsinari, Valentijn R. N. Pauwels, Edoardo Daly, Jos van Dam, Remko Uijlenhoet, and Rebecca Doble
- Abstract
The bio-physical processes occurring in the unsaturated zone have a direct impact on the water table dynamics. Conceptual models, with a simplified representation of the unsaturated zone dynamics, are often selected for coupling to groundwater models, while physically-based models are widely used, particularly at the field scale, for an accurate representation of the water transport. The recharge rates estimated by these Unsaturated Zone Models (UZMs) can then be used as input for groundwater models. Because recharge estimates are always affected by uncertainty, model-data fusion methods, such as data assimilation, can be used to reduce the uncertainty in the model results. In this study, the required complexity (i.e. conceptual versus physically-based) of the unsaturated zone model to update groundwater models through the assimilation of evapotranspiration (ET) rates is assessed for a water-limited site in South Australia. ET rates are assimilated because they have been shown to be related to the groundwater table dynamics, and thus form the link between remote sensing data and the deeper parts of the soil profile. It has been found that, under the test site conditions, a conceptual UZM can be used to improve groundwater model results through the assimilation of ET rates.
- Published
- 2020
45. Optimizing SAR-based Flood Extent Assimilation for Improved Flood Inundation Forecasts
- Author
-
Jeffrey P. Walker, Antara Dasgupta, Renaud Hostache, Stefania Grimaldi, Guy Schumann, Valentijn R. N. Pauwels, and Raaj Ramsankaran
- Subjects
Flood myth ,Meteorology ,Environmental science ,Assimilation (biology) - Abstract
Floods can have extremely expensive and often fatal consequences, thereby necessitating accurate flood inundation forecasts for increased preparedness and resilience. In an operational forecasting scenario, inflow uncertainties propagated from precipitation forecasts dominate and lead to inherently erroneous predictions of flood inundation, frequently impeding their application to rescue and response operations. Thus, it is expected that assimilating independent inundation observations, from Synthetic Aperture Radar (SAR) sensors for example, may reduce the inherent uncertainty in hydraulic modelling. The increasing number of SAR satellites, with their all-weather/all-day imaging capabilities, have increased the probability of monitoring flood dynamics from space. SAR-based flood extents were previously used to indirectly retrieve floodplain water levels in conjunction with digital elevation models. However, studies highlighted this process as an additional source of uncertainty, leading to the development of algorithms for the direct assimilation of flood extent into hydraulic flood inundation forecasting chains. The efficiency of flood extent assimilation is keenly sensitive to the spatiotemporal observation characteristics, and so the expected improvement in the forecast strongly depends on the acquisition timing with respect to the position of the flood wave. In this study, numerical experiments were used to simulate multiple spatiotemporal SAR acquisition scenarios, to identify the optimum measurement design for targeted satellite acquisition, to best facilitate flood extent assimilation. A particle filter based flood extent assimilation framework was developed using the hydraulic model LISFLOOD-FP, and implemented for the 2011 flood event in the Clarence Catchment, Australia. An operational forecasting scenario was emulated for the open loop model ensemble, with the consideration of temporally correlated, variance changing uncertainties in inflows, simulating hydrological model forecasts. The impact of assimilating flood extent at reaches exhibiting uniform flow behaviour, with different combinations of first visit and revisit intervals were investigated. Results indicate that the optimum timing and frequency of targeted SAR acquisitions differs with respect to reach hydraulic characteristics and that images acquired after the peak is observed in the channel are most informative for the forecast. Note that the maximum inundation extent in the floodplain always follows the channel peak, and therefore, post-peak images with respect to the within reach flood wave could improve predictions during the peak in the floodplain. Moreover, a single image assimilated at a reaches exhibiting more diffusive flow behaviour just after the peak, could result in improvements comparable to the assimilation of multiple images elsewhere. Findings from the study will allow the optimal utilization of SAR imagery to overcome localized model uncertainties, and help to maximize the accuracy of inundation forecasts. Keywords: Flood inundation modelling, flood extent assimilation, SAR, data assimilation, hydraulic modelling, forecast uncertainty
- Published
- 2020
46. Efficient simulation of flood events using machine learning
- Author
-
Mahesh Prakash, Edoardo Daly, Jihane Elyahyioui, Valentijn R. N. Pauwels, and François Petitjean
- Subjects
Flood myth ,Computer science ,business.industry ,Artificial intelligence ,Machine learning ,computer.software_genre ,business ,computer - Abstract
Flooding is one of the most common and costly natural hazards at global scale. Flood models are important in supporting flood management. This is a computationally expensive process, due to the high nonlinearity of the equations involved and the complexity of the surface topography. New modelling approaches based on deep learning algorithms have recently emerged for multiple applications.This study aims to investigate the capacity of machine learning to achieve spatio-temporal flood modelling. The combination of spatial and temporal input data to obtain dynamic results of water levels and flows from a machine learning model on multiple domains for applications in flood risk assessments has not been achieved yet. Here, we develop increasingly complex architectures aimed at interpreting the raw input data of precipitation and terrain to generate essential spatio-temporal variables (water level and velocity fields) and derived products (flood maps) by training these based on hydrodynamic simulations.An extensive training dataset is generated by solving the 2D shallow water equations on simplified topographies using Lisflood-FP.As a first task, the machine learning model is trained to reproduce the maximum water depth, using as inputs the precipitation time series and the topographic grid. The models combine the spatial and temporal information through a combination of 1D and 2D convolutional layers, pooling, merging and upscaling. Multiple variations of this generic architecture are trained to determine the best one(s). Overall, the trained models return good results regarding performance indices (mean squared error, mean absolute error and classification accuracy) but fail at predicting the maximum water depths with sufficient precision for practical applications.A major limitation of this approach is the availability of training examples. As a second task, models will be trained to bring the state of the system (spatially distributed water depth and velocity) from one time step to the next, based on the same inputs as previously, generating the full solution equivalent to that of a hydrodynamic solver. The training database becomes much larger as each pair of consecutive time steps constitutes one training example.Assuming that a reliable model can be built and trained, such methodology could be applied to build models that are faster and less computationally demanding than hydrodynamic models. Indeed, in with the synthetic cases shown here, the simulation times of the machine learning models (< seconds) are far shorter than those of the hydrodynamic model (a few minutes at least). These data-driven models could be used for interpolation and forecasting. The potential for extrapolation beyond the range of training datasets will also be investigated (different topography and high intensity precipitation events).
- Published
- 2020
47. Feasibility of Improving Groundwater Modeling by Assimilating Evapotranspiration Rates
- Author
-
Valentijn R. N. Pauwels, Edoardo Daly, Rebecca Doble, and Simone Gelsinari
- Subjects
Hydrology ,Data assimilation ,Evapotranspiration ,MODFLOW ,Vadose zone ,Environmental science ,Ensemble Kalman filter ,Groundwater model ,Groundwater ,Water Science and Technology - Published
- 2020
48. The Soil Moisture Active Passive Experiments: Validation of the SMAP Products in Australia
- Author
-
Liujun Zhu, Simon Yueh, Christian von Hebel, Ying Gao, Edward J. Kim, Jeffrey P. Walker, Nan Ye, Olivier Merlin, Xiaoling Wu, Richard de Jeu, Christoph Rudiger, Sabah Sabaghy, François Jonard, Luigi J. Renzullo, Thomas J. Jackson, Valentijn R. N. Pauwels, and Monash University [Melbourne]
- Subjects
L band ,Radiometer ,0211 other engineering and technologies ,Sampling (statistics) ,02 engineering and technology ,Vegetation ,law.invention ,law ,Brightness temperature ,Calibration ,General Earth and Planetary Sciences ,Environmental science ,14. Life underwater ,Electrical and Electronic Engineering ,Radar ,[SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology ,[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment ,Water content ,ComputingMilieux_MISCELLANEOUS ,021101 geological & geomatics engineering ,Remote sensing - Abstract
The fourth and fifth Soil Moisture Active Passive Experiments (SMAPEx-4 and -5) were conducted at the beginning of the SMAP operational phase, May and September 2015, to: 1) evaluate the SMAP microwave observations and derived soil moisture (SM) products and 2) intercompare with the Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions over the Murrumbidgee River Catchment in the southeast of Australia. Airborne radar and radiometer observations at the same microwave frequencies as SMAP were collected over SMAP footprints/grids concurrent with its overpass. In addition, intensive ground sampling of SM, vegetation water content, and surface roughness was carried out, primarily for validation of airborne SM retrieval over six $\sim 3\,\,\text {km} \times 3$ km focus areas. In this study, the SMAPEx-4 and -5 data sets were used as independent reference for extensively evaluating the brightness temperature and SM products of SMAP, and intercompared with SMOS and Aquarius under a wide range of SM and vegetation conditions. Importantly, this is the only extensive airborne field campaign that collected data while the SMAP radar was still operational. The SMAP radar, radiometer, and derived SM showed a high agreement with the SMAPEx-4 and -5 data set, with a root-mean-squared error (RMSE) of ~3 K for radiometer brightness temperature, and an RMSE of $\sim 0.05~\text{m}^{3}/\text{m}^{3}$ for the radiometer-only SM product. The SMAP radar backscatter had an RMSE of 3.4 dB, while the retrieved SM had an RMSE of 0.11 m3/m3 when compared with the SMAPEx-4 data set.
- Published
- 2020
49. Evaluation of State and Bias Estimates for Assimilation of SMOS Retrievals Into Conceptual Rainfall-Runoff Models
- Author
-
Gabrielle De Lannoy, Valentijn R. N. Pauwels, and Harrie-Jan Hendricks Franssen
- Subjects
Estimation ,State variable ,Data assimilation ,Hydrology (agriculture) ,Climatology ,Environmental science ,ddc:333.7 ,Ensemble Kalman filter ,State (computer science) ,General Medicine ,Structural basin ,Water content - Abstract
For an accurate estimation of land surface state variables through remote sensing data assimilation, it is important to estimate the forecast and observation biases as well. This study focuses on the evaluation of a methodology to estimate land surface state variables, together with model forecast and observation biases. Two conceptual rainfall-runoff models (HBV and GRKAL) are used for this purpose. Soil moisture data, retrieved by the Soil Moisture Ocean Salinity (SMOS) mission, are assimilated into these models for 59 unregulated sub-basins of the Murray-Darling basin in Australia. When both models simulate similar soil moisture values, the methodology results in similar forecast and observation bias estimates for both models. The same behavior is obtained when the temporal evolution of the soil moisture simulations is different, but with a similar long-term mean climatology. However, when the long-term mean climatology of both models is different, but with a similar temporal evolution, the bias estimates from both models have a different climatology as well, but with a high temporal correlation. The overall conclusion from this paper is that observation bias estimation is of key importance when updating internal state variables in a conceptual rainfall-runoff system that is calibrated to produce realistic discharge output for possibly biased internal state variables, and that the relative partitioning of bias into forecast and observation bias remains a model-dependent challenge.
- Published
- 2020
50. Towards operational SAR-based flood mapping using neuro-fuzzy texture-based approaches
- Author
-
Antara Dasgupta, Stefania Grimaldi, Raaj Ramsankaran, Jeffrey P. Walker, and Valentijn R. N. Pauwels
- Subjects
Synthetic aperture radar ,Adaptive neuro fuzzy inference system ,010504 meteorology & atmospheric sciences ,Neuro-fuzzy ,Mean squared error ,Flood myth ,Computer science ,business.industry ,Dimensionality reduction ,0208 environmental biotechnology ,Probabilistic logic ,Soil Science ,Geology ,Pattern recognition ,02 engineering and technology ,01 natural sciences ,Fuzzy logic ,020801 environmental engineering ,Artificial intelligence ,Computers in Earth Sciences ,business ,0105 earth and related environmental sciences ,Remote sensing - Abstract
Synthetic Aperture Radar (SAR) data are currently the most reliable resource for flood monitoring, though still subject to various uncertainties, which can be objectively represented with probabilistic flood maps. Moreover, the growing number of SAR satellites has increased the likelihood of observing a flood event from space through at least a single SAR image, but generalized methods for flood classification independent of sensor characteristics need to be developed, to fully utilize these images for disaster management. Consequently, a neuro-fuzzy flood mapping technique is proposed for texture-enhanced single SAR images. Accordingly, any SAR image is first processed to generate second-order statistical textures, which are subsequently optimized using a dimensionality reduction technique. The flood and non-flood classes are then modelled within a fuzzy inference system using Gaussian curves. Parameterization is achieved by training a neural network on the image through user-defined polygons. The results of the optimized texture-based neuro-fuzzy classification were compared against the performance of the SAR image alone and that of SAR enhanced with randomly selected texture features. This approach was tested for a COSMO-SkyMed SAR image at two validation sites, for which high resolution aerial photographs were available. An overall accuracy assessment using reliability diagrams demonstrated a reduction of 54.2% in the Weighted Root Mean Squared Error (WRMSE) values compared to the stand-alone use of SAR. WRMSE values estimated for the proposed method varied from 0.027 to 0.196. A fuzzy validation exercise was also proposed to account for the uncertainty in manual flood identification from aerial photography, resulting in fuzzy spatial similarity values ranging from 0.67 to 0.92, with higher values representing better performance. Results suggest that the proposed approach has demonstrated potential to improve operational SAR-based flood mapping.
- Published
- 2018
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.