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See detailModel reduction for simulating the dynamic behavior of parabolic troughs and a thermocline energy storage in a micro-solar power unit
Dickes, Rémi ULg; Desideri, Adriano ULg; Lemort, Vincent ULg et al

Conference (2015, July)

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges ... [more ▼]

Micro-scale concentrated solar power plants are characterized by strong transients and mostly operate in off-design working conditions. Both the sizing and the control of these systems are key challenges whose optimization requires powerful dynamic modeling tools. In this context, a system featuring a solar field of parabolic troughs, a thermocline thermal energy storage and a 5kWe organic Rankine cycle (ORC) power unit is modeled in the Modelica language. Model reduction methods applied to the solar field and the thermal storage are investigated and analyzed to improve the computational efficiency of the problem. Each model is described and integrated in the open-source ThermoCycle library. Results of simulation under identical operating conditions are compared and the benefits and limitations of model reduction are assessed. [less ▲]

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See detailAn XFEM/CZM implementation for massively parallel simulations of composites fracture
Vigueras, Guillermo; Sket, Federico; Samaniego, Cristobal et al

in Composite Structures (2015), 125

Because of their widely spread use in many industries, composites are the subject of many research campaigns. More particularly, the development of both accurate and flexible numerical models able to ... [more ▼]

Because of their widely spread use in many industries, composites are the subject of many research campaigns. More particularly, the development of both accurate and flexible numerical models able to capture their intrinsically multiscale modes of failure is still a challenge. The standard finite element method typically requires intensive remeshing to adequately capture the geometry of the cracks and high accuracy is thus often sacrificed in favor of scalability, and vice versa. In an effort to preserve both properties, we present here an extended finite element method (XFEM) for large scale composite fracture simulations. In this formulation, the standard FEM formulation is partially enriched by use of shifted Heaviside functions with special attention paid to the scalability of the scheme. This enrichment technique offers several benefits, since the interpolation property of the standard shape function still holds at the nodes. Those benefits include (i) no extra boundary condition for the enrichment degree of freedom, and (ii) no need for transition/blending regions; both of which contribute to maintain the scalability of the code. Two different cohesive zone models (CZM) are then adopted to capture the physics of the crack propagation mechanisms. At the intralaminar level, an extrinsic CZM embedded in the XFEM formulation is used. At the interlaminar level, an intrinsic CZM is adopted for predicting the failure. The overall framework is implemented in ALYA, a mechanics code specifically developed for large scale, massively parallel simulations of coupled multi-physics problems. The implementation of both intrinsic and extrinsic CZM models within the code is such that it conserves the extremely efficient scalability of ALYA while providing accurate physical simulations of computationally expensive phenomena. The strong scalability provided by the proposed implementation is demonstrated. The model is ultimately validated against a full experimental campaign of loading tests and X-ray tomography analyses for a chosen very large scale. [less ▲]

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See detailRuthenium–arene catalysts bearing N-heterocyclic carbene ligands for olefin cyclopropanation and metathesis
Méret, M.; Maj, A. M.; Demonceau, Albert ULg et al

in Monatshefte für Chemie = Chemical Monthly (2015), 146(7), 1099-1105

Abstract: Ruthenium–arene complexes bearing N-heterocyclic carbene (NHC) ligands with the generic formula [RuCl2(p-cymene)(NHC)] are efficient catalyst precursors for the cyclopropanation of activated ... [more ▼]

Abstract: Ruthenium–arene complexes bearing N-heterocyclic carbene (NHC) ligands with the generic formula [RuCl2(p-cymene)(NHC)] are efficient catalyst precursors for the cyclopropanation of activated olefins with ethyl diazoacetate, and the cis/trans diastereoselectivity of the reaction markedly depends on the steric bulk of the NHC. The procedure was successfully applied to styrene, α-methylstyrene, and various other styrenic derivatives bearing electron-withdrawing or donating substituents on their aromatic rings. The reaction of unactivated internal or terminal alkenes was more sluggish, and the use of norbornene as a substrate afforded only olefin metathesis. Further investigation of the ring-opening metathesis polymerization of this strained cycloolefin in the presence of trimethylsilyldiazomethane led to high molecular weight polynorbornene whose microstructure was not significantly affected by the choice of the NHC ancillary ligand. [less ▲]

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See detailLong-term XMM-Newton investigation of two particle-accelerating colliding-wind binaries in NGC6604: HD168112 and HD167971
De Becker, Michaël ULg

in Monthly Notices of the Royal Astronomical Society (2015), 451(1), 5589-5599

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking ... [more ▼]

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking into account recent information about their multiplicity and orbital parameters. The two targets, HD168112 and HD167971 appear to be overluminous in X-rays, lending additional support to the idea that a significant contribution of the X-ray emission comes from colliding-wind regions. The variability of the X-ray flux from HD168112 is interpreted in terms of varying separation expected to follow the 1/D rule for adiabatic shocked winds. For HD167971, marginal decrease of the X-ray flux in September 2002 could tentatively be explained by a partial wind eclipse in the close pair. No long-term variability could be demonstrated despite the significant difference of separation between 2002 and 2014. This suggests the colliding-wind region in the wide orbit does not contribute a lot to the total X-ray emission, with a main contribution coming from the radiative shocked winds in the eclipsing pair. The later result provides evidence that shocks in a colliding-wind region may be efficient particle accelerators even in the absence of bright X-ray emission, suggesting particle acceleration may operate in a wide range of conditions. Finally, in hierarchical triple O-type systems, thermal X-rays do not necessarily constitute an efficient tracer to detect the wind-wind interaction in the long period orbit. [less ▲]

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See detailSpectroscopic survey of Kepler stars. I. HERMES/Mercator observations of A- and F-type stars
Niemczura, E.; Murphy, S. J.; Smalley, B. et al

in Monthly Notices of the Royal Astronomical Society (2015), 450

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally ... [more ▼]

The Kepler space mission provided near-continuous and high-precision photometry of about 207,000 stars, which can be used for asteroseismology. However, for successful seismic modelling it is equally important to have accurate stellar physical parameters. Therefore, supplementary ground-based data are needed. We report the results of the analysis of high-resolution spectroscopic data of A- and F-type stars from the Kepler field, which were obtained with the HERMES spectrograph on the Mercator telescope. We determined spectral types, atmospheric parameters and chemical abundances for a sample of 117 stars. Hydrogen Balmer, Fe I, and Fe II lines were used to derive effective temperatures, surface gravities, and microturbulent velocities. We determined chemical abundances and projected rotational velocities using a spectrum synthesis technique. The atmospheric parameters obtained were compared with those from the Kepler Input Catalogue (KIC), confirming that the KIC effective temperatures are underestimated for A stars. Effective temperatures calculated by spectral energy distribution fitting are in good agreement with those determined from the spectral line analysis. The analysed sample comprises stars with approximately solar chemical abundances, as well as chemically peculiar stars of the Am, Ap, and Lambda Boo types. The distribution of the projected rotational velocity, Vsini, is typical for A and F stars and ranges from 8 to about 280 km/s, with a mean of 134 km/s. [less ▲]

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See detailLate Holocene history of the Fuji Five Lakes (Japan)
Lamair, Laura ULg; Hubert, Aurelia ULg; Boes, Evelien et al

Conference (2015, July)

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See detailReinforcement Learning of Heuristic EV Fleet Charging in a Day-Ahead Electricity Market
Vandael, Stijn; Claessens, Bert; Ernst, Damien ULg et al

in IEEE Transactions on Smart Grid (2015), 6(4), 1795-1805

This paper addresses the problem of defining a day-ahead consumption plan for charging a fleet of electric vehicles (EVs), and following this plan during operation. A challenge herein is the beforehand ... [more ▼]

This paper addresses the problem of defining a day-ahead consumption plan for charging a fleet of electric vehicles (EVs), and following this plan during operation. A challenge herein is the beforehand unknown charging flexibility of EVs, which depends on numerous details about each EV (e.g., plug-in times, power limitations, battery size, power curve, etc.). To cope with this challenge, EV charging is controlled during opertion by a heuristic scheme, and the resulting charging behavior of the EV fleet is learned by using batch mode reinforcement learning. Based on this learned behavior, a cost-effective day-ahead consumption plan can be defined. In simulation experiments, our approach is benchmarked against a multistage stochastic programming solution, which uses an exact model of each EVs charging flexibility. Results show that our approach is able to find a day-ahead consumption plan with comparable quality to the benchmark solution, without requiring an exact day-ahead model of each EVs charging flexibility. [less ▲]

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See detailExploiting Interspecific Genetic Variability for Improving Common bean for higher productivity on soils presenting biotic and abiotic stresses
Butare, Louis ULg

Doctoral thesis (2015)

Biotic and abiotic stresses often occur in the same field of rural poor farmer households in tropical countries resulting in heavy losses of common bean yields. To improve resistance of common beans ... [more ▼]

Biotic and abiotic stresses often occur in the same field of rural poor farmer households in tropical countries resulting in heavy losses of common bean yields. To improve resistance of common beans, sensitive Phaseolus vulgaris (SER16) was crossed to resistant P. coccineus (G35346-3Q) to create 94 F5:6 recombinant inbred lines (RILs) of the pedigree SER16♀ x (SER16♀ x G35346-3Q♂). The objectives of this study were to (i) identify potential parents for resistance to Al, drought and Fusarium root rot among 11 bean genotypes, (ii) to evaluate 94 F5:6 Recombinant Inbred Lines (RILs) of the cross SER 16♀ x (SER 16♀ x G35346-3Q♂) both for their resistance to Al and /or drought, (iii) to evaluate RILs for resistance to Fusarium root rot, and (iv) to identify QTL for resistance to these stresses. RILs were characterized in greenhouse for resistance to Al using a hydroponic screening employing a nutrient solution with or without 20 μM Al , to Al-toxic acid soil with high Al (HAl) and low Al (LAl) saturation, to terminal drought simulation with and without progressive soil drying, to combined stresses of Al and terminal drought in 80 cm long soil cylinder system, and to Fusarium root rot using inoculated perlite soil and sand (2:1). Two field studies were also carried on in Colombia under rainfed and irrigated conditions in Palmira, and high Al saturated acid soil in Santander of Quilichao. Our studies confirmed the superiority in Al response of Andean common beans in greenhouse trials compared to Middle American type for several root traits. Each screening method of our Al greenhouse experiments permitted an evaluation of different aspects of root traits. The two parents were virtually equal for tap root elongation rate at 24 h in the 20 μM Al treatment at about 1.4 mm h-1 while progenies ranged from less than 1-1.75 mm h-1. The correlation between leaf area and total root length was highly significant under high Al saturation (r = 0.70***) for HAl-acid soil. Two genotypes (ALB88 and ALB 91) emerged as strong multiple trait lines for the two abiotic stresses. Fusarium root rot induced root growth inhibition as high as 80.8% for the susceptible ALB 5, while resistant RILs (ALB45, ALB41, ALB126, ALB84, ALB49, ALB34, ALB88 and ALB85) didn`t show any inhibition . Seed yield under drought stress conditions was positively associated to 100-seed weight both under irrigated field (r = 0.28**) and rainfed field (r = 0.36***), and negatively associated to days to maturity (DTM) (r = - 0.36***) in field evaluation in Al-toxic acid soil in Quilichao (Colombia). QTLs for important traits including root characteristics under high Al , grain yield and yield components for drought and high Al saturation soil were identified. The use of both soil and hydroponic system, and field could contribute to evaluation of breeding materials to identify genotypes that combine Al resistance with acid soil tolerance, drought and root rot tolerance. [less ▲]

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See detailMetal bioavailability and bioaccumulation in the polychaete Nereis virens (Sars): the effects of site-specific sediment characteristics
Pini, Jennifer; Richir, Jonathan ULg; Watson, Gordon

in Marine Pollution Bulletin (2015), 95(2), 565575

The present study investigates the relationships between copper (Cu) and zinc (Zn) concentrations in sediment, pore water and their bioaccumulation in the polychaete Nereis (Alitta) virens, as well as the ... [more ▼]

The present study investigates the relationships between copper (Cu) and zinc (Zn) concentrations in sediment, pore water and their bioaccumulation in the polychaete Nereis (Alitta) virens, as well as the importance of site-specific sediment characteristics in that process. Sediment, pore water and N. virens were sampled from seven sites with different pollution histories along the English Channel coast. Results showed that site-specific metal levels and sediment characteristics were important in determining the bioavailability of metals to worms. Significant correlations were found between Cu in the sediment and in the pore water and between Zn in the pore water and in N. virens. Zn from the pore water was thus more readily available from a dissolved source to N. virens than Cu. Data also showed that metal concentrations in N. virens were lower than those found in other closely related polychaetes, indicating that it may regulate tissue concentrations of Cu and Zn. [less ▲]

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See detailCould alternative solanaceous hosts act as refuges for the tomato leafminer, Tuta absoluta?
Bawin, Thomas ULg; Dujeu, David ULg; De Backer, Lara ULg et al

in Arthropod-Plant Interactions (2015)

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), is a widespread devastating pest reported to develop on economically important solanaceous plants. The characterization of its effective ... [more ▼]

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), is a widespread devastating pest reported to develop on economically important solanaceous plants. The characterization of its effective host range could help to understand and prevent the dispersion behavior of the insect in the environment. In this study, the ability of T. absoluta to locate and develop on wild (Solanum nigrum, Atropa belladonna, Datura stramonium) and cultivated (Solanum tuberosum) solanaceous plant species under laboratory conditions was assessed. Dual-choice behavioral assays performed in flying tunnels (S. tuberosum versus another plant) revealed that adult distribution and female oviposition did not differ between Solanum species, which were preferred to the other tested plants. The volatile molecules released by each tested plant species provide some explanations in the observed behavioral discrimination: S. nigrum and S. tuberosum volatile profiles were similar, and were presenting quantitative and qualitative differences with the other tested Solanaceous plants. To determine whether the host plant choice was adaptive or not, we have finally conducted fitness assays, by rearing T. absoluta larvae on each plant species and have shown that Solanum species allowed higher larval survivability and lower development time (from egg to adult emergency) compared to the other plants. We conclude that Solanum species are suitable host plants for T. absoluta, but other Solanaceous plant species could be opportunistically colonized with fewer incidences. [less ▲]

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See detailWild boar movement ecology across scales: Insights from a population expanding into agroecosystems of Southern Belgium
Morelle, Kevin ULg

Doctoral thesis (2015)

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until ... [more ▼]

Over the time, ungulates have seen their populations continuously changing under the e ect of direct, i.e. hunting pressure, and indirect, i.e. land-use changes, human activities. Under control until recently, ungulates have progressively adapted to these modi cations and are now able to cope with human-shaped environments, consequently their number and range have greatly and worryingly increased. More particularly, among ungulates species, the wild boar Sus scrofa raises important concerns due to its environmental, economic and social impacts on modern societies. Understanding the ecology of ungulates species and their ability to survive within highly dynamic and seasonal ecosystems, such as agricultural environment, is thus necessary to better mitigate their negative impacts and to sustainably manage growing and expanding populations. Although only recently studied, movement ecology of animal is an important species trait that allows animal to adapt to rapid environmental changes. Considering movement as the resulting interaction of the animal’s internal state, navigation and motion capacity as well as of the e ect of the surrounding environment (“external factors”), provides a clear conceptual framework enabling to study patterns, mechanisms and processes, such as coping with land-use changes. In this thesis, we study the case of an expanding wild boar population in Southern Belgium and consider the movement ecology of the species to understand how wild boar colonize and ourish in agroecosystems. More speci cally, the thesis aims at i) reviewing quantitatively and qualitatively the scienti c literature about wild boar movement ecology, and ii) analyzing the spatial response of wild boar to agroecosystems in terms of movement and habitat selection across three spatial and temporal scales. The literature review highlights that wild boar is the least studied ungulates species in terms of movement ecology.We suggest that this is likely due i) to the relative complexity of tting tracking devices to this species, and ii) to its generalist diet making the species not suitable to test foraging hypotheses. Among existing studies, a large part focuses on the role of external factors (e.g. hunting, landscape features) on movement while others components of the movement ecology framework (internal state, navigation and motion capacity) remain poorly studied. However, when assuming behavioral similarity between wild and domestic boars, experimental studies on captive animals show how wild boar can develop complex movement strategies by using their highly developed cognitive and sensory abilities, and spatial memory. The spatio-temporal analysis suggests a scale-speci c response of wild boar to agricultural habitat. At the intermediate scale (landscape, seasonal), wild boar uses seasonal habitat shift strategies towards agricultural areas, while at broader scale (regional, decades), wild boar avoids this habitat, preferring the forest habitat to spread and extend its occupancy range. This results in a contradiction with our preliminary hypothesis that increased area of cultivations providing cover (maize, rapeseed, cereals) facilitates wild boar population expansion. Furthermore, we show that besides the use of forest habitat, high population density is a major driving factor of the colonization of agroecosystems by wild boar. The ne-scale analysis (home range, daily), highlights the large variety of spatial behaviors (area restricted search, central place foraging, nomadism, dispersing) wild boar is able to use to cope with heterogeneous environments. In terms of management of the species, the results of this thesis suggest that it is required to lower the population density in order to limit the population spread into agroecosystems, not only at the margin of expansion but all over the species’ range. Furthermore, we recommend developing more exible control strategies taking into account both the spatial abilities of the species and the complexity and dynamics of the environment. For example, the creation of a seasonal landscape of fear could be promoted, i.e. reducing attractivity of agricultural lands by increasing risk sensation (e.g. hunting with dogs all along the growing season). However, in our opinion, the success of any management strategy requires rst to tackle the issue of the decreasing number of hunters observed in large part of Europe and to improve communication among the di erent stakeholders (hunting associations, farmers, public administration). Indeed, while ungulates have progressively adapted to human-induced changes, the capacity of humans to adapt to this new human-ungulate relation is questionable. [less ▲]

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See detailPerturbations de l'épissage des ARN pré-messagers par les agents chimiothérapeutiques: mécanismes d'action du cisplatine et impact sur la mortalité des cellules cancéreuses
Gabriel, Maude ULg

Doctoral thesis (2015)

L’épissage alternatif est un processus qui concerne plus de 90% des pré-ARN messagers et qui contribue largement à la diversité protéique. Il est régulé par une série de facteurs d’épissage qui se lient ... [more ▼]

L’épissage alternatif est un processus qui concerne plus de 90% des pré-ARN messagers et qui contribue largement à la diversité protéique. Il est régulé par une série de facteurs d’épissage qui se lient sur des séquences situées sur les transcrits primaires. L’activité de ces facteurs d’épissage est régulée, entre autres, par divers signaux externes et voies de signalisation.  Les agents chimiothérapeutiques peuvent altérer la régulation de l’épissage et, ainsi, modifier la séquence d’un grand nombre d’ARN messagers et, éventuellement, la fonction des protéines qui en résultent. Cependant, l’implication de ces mécanismes dans la thérapie anticancéreuse demeure mal connue en termes d’efficacité thérapeutique, de diagnostic, de pronostic, de développement de résistances aux traitements et d’induction d’effets secondaires. L’objectif principal de cette étude est d’évaluer si la régulation de l’épissage par le cisplatine est critique pour son activité anticancéreuse. L’analyse du transcriptome de cellules mammaires cancéreuses traitées avec du cisplatine a permis d’identifier de nombreuses altérations d’épissage induites par la chimiothérapie. Parmi les 700 évènements observés, un grand nombre touche des transcrits impliqués dans le cycle cellulaire et dans la régulation de l’épissage lui-même.   Bien que le cisplatine induise des dommages au niveau de l’ADN, nous avons exclu la participation des membres de la voie des dommages à l’ADN, tels que ATM, ATR, DNA-PK et p53, dans les altérations d’épissage induites par le cisplatine. Les PI3K de class I (p110) et la voie MEK/ERK sont , en revanche, requises.  L’utilisation d’une banque de plus de 50 siRNA ciblant des protéines se liant à l’ARN, en particulier des facteurs d’épissage, nous a permis d’évaluer l’implication de ces facteurs dans les modifications d’épissage observées après le traitement au cisplatine. Il est apparu que la réduction de l’expression de certains facteurs dont SF3A1, RBM39, U2AF1 et snRNP70 mime les effets du cisplatine. A l’inverse, l’inhibition de SRSF4 réprime ces effets.  Par co-immunoprécipitation, nous avons observé un lien physique entre le facteur de transcription c-Jun et les facteurs d’épissage SF3A1 et RBM39. Alors que cette liaison ne semble pas être affectée par le cisplatine, des modifications du statut de phosphorylation de c-Jun ont été observées après traitement au cisplatine. La déplétion de c-Jun et l’inhibition d’AP-1 corrigent en partie l’effet du cisplatine sur l’épissage, suggérant leur implication dans le processus.   Finalement, nous avons montré que la déplétion en SRSF4 réduit la mortalité cellulaire induite par le cisplatine, alors que la déplétion en SF3A1 et RBM39 l’augmente. Ces résultats montrent une corrélation entre épissage et mort cellulaire et suggèrent que la modulation de l’épissage pourrait être utilisée comme thérapie adjuvante afin d’augmenter l’efficacité de la chimiothérapie.   [less ▲]

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See detailMultiscale structure characterization of sawdust-waste water sludge extrudates dried in a pilot-scale fixed bed
Li, Jie ULg; Plougonven, Erwan ULg; Fraikin, Laurent ULg et al

in Biomass and Bioenergy (2015), 81(0), 98-107

Abstract Convective drying of waste water sludge and sawdust-sludge mixtures in a pilot-scale fixed bed was studied. Drying was performed in a cross-flow convective dryer using 500 g of wet material ... [more ▼]

Abstract Convective drying of waste water sludge and sawdust-sludge mixtures in a pilot-scale fixed bed was studied. Drying was performed in a cross-flow convective dryer using 500 g of wet material extruded through a disk with circular dies 12 mm in diameter. The structure of the bed mainly shows volume shrinkage and crack formation during drying. Several characterization techniques were used over a wide range of scales from nm up to mm. The overall bed structure was imaged with X-ray macrotomography, at a resolution of 0.36 mm per pixel. Single extrudates were scanned with X-ray microtomography, at a resolution of 41 μm per pixel. Pore structure of the dried samples were characterized by mercury porosimetry (7.5 nm < dp < 150 μm). Results show significant structural changes on all scales with increasing amounts of sawdust: shrinkage decreases, crack formation increases, and the pores become larger. This confirms the benefits of sawdust addition for sludge drying applications. [less ▲]

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See detailRiga. Une capitale balte à l'époque de l'Art nouveau
Folville, Xavier ULg

Conference given outside the academic context (2015)

Au début du XVIIIe siècle, Riga, ancienne ville hanséatique, faisait partie de l'empire tsariste dont elle était un des ports les plus importants ; elle connut une histoire compliquée et douloureuse ... [more ▼]

Au début du XVIIIe siècle, Riga, ancienne ville hanséatique, faisait partie de l'empire tsariste dont elle était un des ports les plus importants ; elle connut une histoire compliquée et douloureuse, partagée avec les autres pays baltes. A la fin du XIXe siècle, la destruction des anciens remparts facilite son extension sur de nouveaux territoires et permet de répondre à l'explosion démographique et au développement économique du moment. Au tournant du siècle, l’Art nouveau s’impose comme le style moderne qui correspond à une ville dynamique. Mais ici, c’est un Art nouveau très différent de celui que nous connaissons à Bruxelles. Teinté de symbolisme dans sa décoration, animé par un sentiment de renouveau national, d’esprit romantique, il engendre des immeubles, des rues, voire des quartiers entiers ou des palais qui seront édifiés jusqu’à la Première Guerre mondiale. Riga, consciente de son patrimoine, est reconnue par l’Unesco ; de nombreux bâtiments sont restaurés et un musée-témoin de l’art de vivre à cette époque est ouvert au public. La conférence propose de faire une courte promenade illustrée dans ce patrimoine. [less ▲]

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See detailAssessment of climate change effects on groundwater resource in transient conditions
Goderniaux, Pascal; Wildemeersch, Samuel; Brouyère, Serge ULg et al

Conference (2015, June 27)

A sophisticated transient weather generator (WG) in combination with an integrated surface-subsurface hydrological model (HydroGeoSphere) are used for producing a stochastic generation of large numbers of ... [more ▼]

A sophisticated transient weather generator (WG) in combination with an integrated surface-subsurface hydrological model (HydroGeoSphere) are used for producing a stochastic generation of large numbers of equiprobable climatic time series, representing transient climate change, and assess impacts on groundwater resources in a probabilistic way. The modelling approach, involving the catchment-scale fully integrated surface-subsurface model, is described in Goderniaux et al. [2009]. Biased-corrected climate change scenarios are applied as input of the hydrological model to quantify their impact on groundwater resources. In Goderniaux et al. [2011], the integrated model is used in combination with a stochastic daily weather generator (WG). This WG allowed generating a large number of equiprobable climate change scenarios representative of a full transient climate between 2010 and 2085. These scenarios enabled to account for the transient nature of the future climate change, and to assess the uncertainty related to the weather natural variability. The downscaling method considers changes in the climatic means, but also in the distribution of wet and dry days. This new methodology is applied for the unconfined chalky aquifer of the Geer catchment in Belgium. A general decrease of the mean groundwater piezometric heads, has been calculated. The approach allowed also to assess different uncertainty sources: (1) the uncertainty linked to the calibration of the hydrological model, using 'UCODE_2005'; (2) the uncertainty linked to the global and regional climatic models (GCMs and RCMs), by using a multi-model ensemble; (3) the uncertainty linked to the natural variability of the weather, by using stochastic climate change scenarios. 30 equiprobable climate change scenarios from 2010 to 2085 have been generated for each of 6 different RCMs. Results show that although the 95% confidence intervals calculated around projected groundwater levels remain large, the climate change signal becomes stronger than that of natural climate variability by 2085. The WG ability to simulate transient climate change enabled the assessment of the likely timescale and associated uncertainty of a specific impact. This methodology constitutes a real improvement in the field of groundwater projections under transient climate change conditions as it enables water managers to analyse risks and take decisions with full knowledge of projected impact and their degree of confidence. [less ▲]