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See detailDetermination of Zinc, Cadmium and Lead Bioavailability in Contaminated Soils at the Single-Cell Level by a Combination of Whole-Cell Biosensors and Flow Cytometry
Hurdebise, Quentin ULg; Tarayre, Cédric ULg; Fischer, Christophe ULg et al

in Sensors (2015)

Zinc, lead and cadmium are metallic trace elements (MTEs) that are widespread in the environment and tend to accumulate in soils because of their low mobility and non-degradability. The purpose of this ... [more ▼]

Zinc, lead and cadmium are metallic trace elements (MTEs) that are widespread in the environment and tend to accumulate in soils because of their low mobility and non-degradability. The purpose of this work is to evaluate the applicability of biosensors as tools able to provide data about the bioavailability of such MTEs in contaminated soils. Here, we tested the genetically-engineered strain Escherichia coli pPZntAgfp as a biosensor applicable to the detection of zinc, lead and cadmium by the biosynthesis of green fluorescent protein (GFP) accumulating inside the cells. Flow cytometry was used to investigate the fluorescence induced by the MTEs. A curvilinear response to zinc between 0 and 25 mg/L and another curvilinear response to cadmium between 0 and 1.5 mg/L were highlighted in liquid media, while lead did not produce exploitable results. The response relating to a Zn2+/Cd2+ ratio of 10 was further investigated. In these conditions, E. coli pPZntAgfp responded to cadmium only. Several contaminated soils with a Zn2+/Cd2+ ratio of 10 were analyzed with the biosensor, and the metallic concentrations were also measured by atomic absorption spectroscopy. Our results showed that E. coli pPZntAgfp could be used as a monitoring tool for contaminated soils being processed. [less ▲]

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See detailRegularized focusing inversion of time-lapse electrical resistivity data: an approach to parametrize the minimum gradient support functional
Nguyen, Frédéric ULg; Hermans, Thomas ULg

Poster (2015, April 15)

Inversion of time-lapse resistivity data allows obtaining ‘snapshots’ of changes occurring in monitored systems for applications such as aquifer storage, geothermal heat exchange, site remediation or ... [more ▼]

Inversion of time-lapse resistivity data allows obtaining ‘snapshots’ of changes occurring in monitored systems for applications such as aquifer storage, geothermal heat exchange, site remediation or tracer tests. Based on these snapshots, one can infer qualitative information on the location and morphology of changes occurring in the subsurface but also quantitative estimates on the degree of changes in certain property such as temperature or total dissolved solid content. Analysis of these changes can provide direct insight into flow and transport and associated processes and controlling parameters. However, the reliability of the analysis is dependent on survey geometry, measurement schemes, data error, and regularization. Survey design parameters may be optimized prior to the monitoring survey. Regularization, on the other hand, may be chosen depending on available information collected during the monitoring. Common approaches consider smoothing model changes both in space and time but it is often needed to obtain a sharp temporal anomaly, for example in fractured aquifers. We here propose to use the alternative regularization approach based on minimum gradient support (MGS) (Zhdanov, 2002) for time-lapse surveys which will focus the changes in tomograms snapshots. MGS will limit the occurrences of changes in electrical resistivity but will also restrict the variations of these changes inside the different zones. A common difficulty encountered by practitioners in this type of regularization is the choice of an additional parameter, the so-called , required to define the MGS functional. To the best of our knowledge, there is no commonly accepted or standard methodology to optimize the MGS parameter . The inversion algorithm used in this study is CRTomo (Kemna 2000). It uses a Gauss-Newton scheme to iteratively minimize an objective function which consists of a data misfit functional and a model constraint functional. A univariate line search is performed at each Gauss-Newton iteration step to find the optimum value of the regularization parameter  which minimizes the data misfit as a function of  while the data misfit is above the desired value and yields the desired target misfit (root-mean square value of error-weighted data misfit equal to 1) at the last iteration for a maximum value of . We propose here to optimize the  of the MGS functional by considering a univariate line search at the first iteration to find the  that minimizes the data misfit. The parameter is then kept constant during the Gauss-Newton iterative scheme. In this contribution, we validate our approach on a numerical benchmark and apply it successfully on a case study in the context of salt tracers in fractured aquifers. Zhdanov M.S. 2002. Geophysical Inverse Theory and Regularization Problems. Elsevier, Amsterdam, 628 p. Kemna A. 2000. Tomographic Inversion of Complex Resistivity - Theory and Application. PhD Thesis, Ruhr University Bochum. [less ▲]

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See detailVariogram-based inversion of time-lapse electrical resistivity data: development and application to a thermal tracing experiment
Hermans, Thomas ULg; Nguyen, Frédéric ULg

Poster (2015, April 15)

Electrical resistivity tomography (ERT) has become a popular imaging methodology in a broad range of applications given its large sensitivity to subsurface parameters and its relative simplicity to ... [more ▼]

Electrical resistivity tomography (ERT) has become a popular imaging methodology in a broad range of applications given its large sensitivity to subsurface parameters and its relative simplicity to implement. More particularly, time-lapse ERT is now increasingly used for monitoring purposes in many contexts such as water content, permafrost, landslide, seawater intrusion, solute transport or heat transport experiments. Specific inversion schemes have been developed for time-lapse data sets. However, in contrast with static inversions for which many techniques including geostatistical, minimum support or structural inversion are commonly applied, most of the methodologies for time-lapse inversion still rely on non-physically based spatial and/or temporal smoothing of the parameters or parameter changes. In this work, we propose a time-lapse ERT inversion scheme based on the difference inversion scheme. We replace the standard smoothness-constraint regularization operator by the parameter change covariance matrix. This operator takes into account the correlation between changes in resistivity at different locations through a variogram computed using independent data (e.g., electromagnetic logs). It may vary for subsequent time-steps if the correlation length is time-dependent. The methodology is first validated and compared to the standard smoothness-constraint inversion using a synthetic benchmark simulating the injection of a conductive tracer into a homogeneous aquifer inducing changes in resistivity values of known correlation length. We analyze the influence of the assumed correlation length on inversion results. Globally, the method yields better results than the traditional smoothness constraint inversion. Even if a wrong correlation length is assumed, the method performs as well as the smoothness constraint since the regularization operator balances the weight given to the model constraint functional in the objective function. Then the methodology is successfully applied to a heat injection and pumping experiment in an alluvial aquifer. The comparison with direct measurements in boreholes (temperature loggers and distributed temperature sensing optic fibres) shows that ERT-derived temperatures and breakthrough curves image reliably the heat plume through time (increasing part of the curve, maximum and tail are correctly retrieved) and space (lateral variations of temperature are observed) with less spatial smoothing than standard methods. The development of new regularization operators for time-lapse inversion of ERT data is necessary given the broad range of applications where ERT monitoring is used. In many studies, independent data are available to derive geostatistical parameters that can be subsequently used to regularize geophysical inversions. In the future, the integration of spatio-temporal variograms into existing 4D inversion schemes should further improve ERT time-lapse imaging. [less ▲]

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See detailRetrievals of formaldehyde from ground-based FTIR and MAX-DOAS observations at the Jungfraujoch station and comparisons with GEOS-Chem and IMAGES model simulations
Franco, Bruno ULg; Hendrick, François; Van Roozendael, Michel et al

in Atmospheric Measurement Techniques (2015), 8

As an ubiquitous product of the oxidation of many volatile organic compounds (VOCs), formaldehyde (HCHO) plays a key role as a short-lived and reactive intermediate in the atmospheric photo-oxidation ... [more ▼]

As an ubiquitous product of the oxidation of many volatile organic compounds (VOCs), formaldehyde (HCHO) plays a key role as a short-lived and reactive intermediate in the atmospheric photo-oxidation pathways leading to the formation of tropospheric ozone and secondary organic aerosols. In this study, HCHO profiles have been successfully retrieved from ground-based Fourier transform infrared (FTIR) solar spectra and UV-visible Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) scans recorded during the July 2010–December 2012 time period at the Jungfraujoch station (Swiss Alps, 46.5° N, 8.0° E, 3580m a.s.l.). Analysis of the retrieved products has revealed different vertical sensitivity between both remote sensing techniques. Furthermore, HCHO amounts simulated by two state-of-the-art chemical transport models (CTMs), GEOSChem and IMAGES v2, have been compared to FTIR total columns and MAX-DOAS 3.6–8 km partial columns, accounting for the respective vertical resolution of each ground-based instrument. Using the CTM outputs as the intermediate, FTIR and MAX-DOAS retrievals have shown consistent seasonal modulations of HCHO throughout the investigated period, characterized by summertime maximum and wintertime minimum. Such comparisons have also highlighted that FTIR and MAX-DOAS provide complementary products for the HCHO retrieval above the Jungfraujoch station. Finally, tests have revealed that the updated IR parameters from the HITRAN 2012 database have a cumulative effect and significantly decrease the retrieved HCHO columns with respect to the use of the HITRAN 2008 compilation. [less ▲]

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See detailUse of NIR Hyperspectral Imaging and dichotomist classification tree based on SVM in order to discriminate roots and crop residues of winter wheat
Eylenbosch, Damien ULg; Fernández Pierna, Juan Antonio; Baeten, Vincent et al

Poster (2015, April 14)

NIR Hyperspectral Imaging coupled with SVM chemometric tool is proposed as an alternative method to the tedious and time-consuming hand sorting step needed before root quantification using the soil coring ... [more ▼]

NIR Hyperspectral Imaging coupled with SVM chemometric tool is proposed as an alternative method to the tedious and time-consuming hand sorting step needed before root quantification using the soil coring method. This method was applied to quantify roots under a winter wheat crop. [less ▲]

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See detailFuture projections of the Greenland ice sheet mass balance using the regional climate MAR model coupled with the GRISLI ice sheet model
Wyard, Coraline ULg; Fettweis, Xavier ULg; Ritz, Catherine

Poster (2015, April 14)

During the two last decades, the Greenland ice sheet (GrIS) contribution to the global mean sea level rise has significantly increased. But, difficulties remain to assess GrIS future contribution because ... [more ▼]

During the two last decades, the Greenland ice sheet (GrIS) contribution to the global mean sea level rise has significantly increased. But, difficulties remain to assess GrIS future contribution because of large uncertainties linked to the feedback between the surface mass balance (SMB) and GrIS topography changes. The regional climate MAR model has been coupled with the GRISLI ice sheet model, in order to account of this feedback in the future projections. The aim of this study is to assess the pertinence of the MAR-GRISLI coupling which requires long computation time. In order to identify GRISLI sensitivity to MAR forcing, GRISLI has been forced with various non-coupled (i.e. using a fixed topography), coupled and modified non-coupled MAR outputs. To adapt the non-coupled MAR outputs to the GRISLI topography changes, we use an interpolation technique based on SMB vs elevation vertical gradient. These experiences evaluate the performances/limits of this interpolation technique used to avoid a RCM-ice sheet model coupling. [less ▲]

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See detailPreliminary results for a hydrogen maser cavity in the TE111 mode
Van Der Beken, Emeline ULg; Léonard, Daniel; Counet, Arnaud et al

Poster (2015, April 13)

An analysis of a hydrogen maser working with an unusual TE111 mode is presented. Different simulations have been carried out and are compared with preliminary results obtained for such a maser. In ... [more ▼]

An analysis of a hydrogen maser working with an unusual TE111 mode is presented. Different simulations have been carried out and are compared with preliminary results obtained for such a maser. In contrast to standard hydrogen maser that exploits the TE011 mode, the TE111 mode allows one to design hydrogen masers with significant reduced dimensions which represents a huge benefit for space applications and in particular for the global positioning system. [less ▲]

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See detailEGU2015 - ENSO forecast using a wavelet-based mode decomposition
Deliège, Adrien ULg; Nicolay, Samuel ULg; Fettweis, Xavier ULg

Conference (2015, April 13)

The aim of this work is to introduce a new method for forecasting major El Niño/ La Niña events with the use of a wavelet-based mode decomposition. These major events are related to sea surface ... [more ▼]

The aim of this work is to introduce a new method for forecasting major El Niño/ La Niña events with the use of a wavelet-based mode decomposition. These major events are related to sea surface temperature anomalies in the tropical Pacific Ocean: anomalous warmings are known as El Niño events, while excessive coolings are referred as La Niña episodes. These climatological phenomena are of primary importance since they are involved in many teleconnections ; predicting them long before they occur is therefore a crucial concern. First, we perform a wavelet transform (WT) of the monthly sampled El Niño Southern Oscillation 3.4 index (from 1950 to present) and compute the associated scale spectrum, which can be seen as the energy carried in the WT as a function of the scale. It can be observed that the spectrum reaches five peaks, corresponding to time scales of about 7, 20, 31, 43 and 61 months respectively. Therefore, the Niño 3.4 signal can be decomposed into five dominant oscillating components with time-varying amplitudes, these latter being given by the modulus of the WT at the associated pseudo-periods. The reconstruction of the index based on these five components is accurate since more than 93% of the El Niño/ La Niña events of the last 60 years are recovered and no major event is erroneously predicted. Then, the components are smoothly extrapolated using polynomials and added together, giving so several years forecasts of the Niño 3.4 index. In order to increase the reliability of the forecasts, we perform several months hindcasts (i.e. retroactive probing forecasts) which can be validated with the existing data. It turns out that most of the major events can be accurately predicted up to three years in advance, which makes our methodology competitive for such forecasts. Finally, we discuss the El Niño conditions currently undergone and give indications about the next La Niña event. [less ▲]

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See detailRetrieval of ammonia from ground-based FTIR measurements and its use for validation of satellite observations by IASI
Dammers, E; Palm, M; Warneke, T et al

in Geophysical Research Abstracts (2015, April 13), 17

Atmospheric Ammonia (NH3) has a major impact on human health and ecosystem services and plays a major role in the formation of aerosols [Erisman et al.,2013; Paulot and Jacob 2014]. NH3 concentrations are ... [more ▼]

Atmospheric Ammonia (NH3) has a major impact on human health and ecosystem services and plays a major role in the formation of aerosols [Erisman et al.,2013; Paulot and Jacob 2014]. NH3 concentrations are highly variable in space and time with overall short lifetime due to deposition and aerosol formation. The global atmospheric budget of nitrogen and in turn NH3 is still uncertain which asks for more ground-based and satellite observations around the world. Recent papers have described the possibility to measure NH3 with satellite infrared sounders which open up the way for calculations of global and regional nitrogen budgets [Clarisse et al 2009,Van Damme et al 2014a]. Validation of the satellite observations is essential to determine the uncertainty in the signal and its potential use. So far available surface layer observations of atmospheric NH3 concentrations have been used for comparisons with total columns retrieved from satellite observations [Van Damme 2014b]. We developed a retrieval for NH3 column density concentrations (molecules NH3/cm2) by fitting a set of spectral windows to ground-based solar absorption Fourier transform infrared (FTIR) measurements with the spectral fitting program SFIT4 [Hase et al., 2004]. The retrieval is then applied to FTIR measurements from a set of spectrometer sites from the Network for detection of Atmospheric Composition Change (NDACC) to retrieve NH3 columns for the sites located in Bremen, Germany; Lauder, New Zealand; Jungfraujoch, Switzerland; and the island of Reunion, France. Using eight years (2005-2013) of retrieved NH3 columns clear seasonal cycles are observed for each of the stations. Maximum concentrations can be related to NH3 emission sources, specific for the regions. A comparison between the retrieved NH3 columns and observations from the recent IASI- NH3 product [Van Damme et al, 2014a] using strict spatial and temporal criteria for the selection of observations showed a good correlation (R=0.82; slope=0.63). The IASI- NH3 columns for the Bremen and Lauder area show similar temporal cycles when compared to the FTIR observations. [less ▲]

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See detailRecent increase of ethane detected in the remote atmosphere of the Northern Hemisphere
Franco, Bruno ULg; Bader, Whitney ULg; Bovy, Benoît ULg et al

Conference (2015, April 13)

Ethane (C2H6) has a large impact on tropospheric composition and air quality because of its involvement in the global VOC (volatile organic compound) – HOx – NOx chemistry responsible for generating and ... [more ▼]

Ethane (C2H6) has a large impact on tropospheric composition and air quality because of its involvement in the global VOC (volatile organic compound) – HOx – NOx chemistry responsible for generating and destroying tropospheric ozone. By acting as a major sink for tropospheric OH radicals, the abundance of C2H6 influences the atmospheric content of carbon monoxide and impacts the lifetime of methane. Moreover, it is an important source of PAN, a thermally unstable reservoir for NOx radicals. On a global scale, the main sources of C2H6 are leakage from the production, transport of natural gas loss, biofuel consumption and biomass burning, mainly located in the Northern Hemisphere. Due to its relatively long lifetime of approximately two months, C2H6 is a sensitive indicator of tropospheric pollution and transport. Using an optimized retrieval strategy (see Franco et al., 2014), we present here a 20-year long-term time series of C2H6 column abundance retrieved from ground-based Fourier Transform InfraRed (FTIR) solar spectra recorded from 1994 onwards at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 3580 m a.s.l.), part of the Network for the Detection of Atmospheric Composition Change (NDACC, see http://www.ndacc.org). After a regular 1994 – 2008 decrease of the C2H6 amounts, which is very consistent with prior major studies (e.g., Aydin et al., 2011; Simpson et al., 2012) and our understanding of global C2H6 emissions, trend analysis using a bootstrap resampling tool reveals a C2H6 upturn and a statistically-significant sharp burden increase from 2009 onwards (Franco et al., 2014). We hypothesize that this observed recent increase in C2H6 could affect the whole Northern Hemisphere and may be related to the recent massive growth in the exploitation of shale gas and tight oil reservoirs. This hypothesis is supported by measurements derived from solar occultation observations performed since 2004 by the Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) instrument and at other NDACC sites, namely Toronto (44° N) and Thule (77° N). Indeed, the recent rates of changes characterizing these data sets are consistent in magnitude and sign with the one derived from the FTIR measurements at Jungfraujoch. In contrast, the ethane time series form Lauder (45° S) shows a monotonic decrease over the last two decades. Investigating both the cause and impact on air quality of the C2H6 upturn should be a high priority for the atmospheric chemistry community. [less ▲]

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See detailHalogenated source gases measured by FTIR at the Jungfraujoch station: updated trends and new target species
Mahieu, Emmanuel ULg; Bader, Whitney ULg; Bovy, Benoît ULg et al

in Geophysical Research Abstracts (2015, April 13), 17

In this contribution, we present decadal time series of halogenated source gases monitored at the high altitude station of the Jungfraujoch (46.5°N, 8°E, 3580 m asl) with Fourier Transform Infared (FTIR ... [more ▼]

In this contribution, we present decadal time series of halogenated source gases monitored at the high altitude station of the Jungfraujoch (46.5°N, 8°E, 3580 m asl) with Fourier Transform Infared (FTIR) spectrometers, within the framework of the Network for the Detection of Atmospheric Composition Change. Total column trends presented in previous studies for CFC-11, -12 and HCFC-22, CCl4, HCFC-142b, CF4 and SF6 will be updated using the latest available Jungfraujoch solar observations. Investigations dealing with the definition of approaches to retrieve additional halogenated source gases from FTIR spectra will also be evoked. Our trend results will be critically discussed and compared with measurements performed in the northern hemisphere by the in situ networks. [less ▲]

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See detailA short dive into the complexity of Jupiter’s aurorae - invited
Bonfond, Bertrand ULg

Conference (2015, April 13)

Aurorae are the atmospheric signatures of energetic processes taking place far in the magnetosphere. One of the most important results brought by high resolution imaging of the UV aurorae at Jupiter is ... [more ▼]

Aurorae are the atmospheric signatures of energetic processes taking place far in the magnetosphere. One of the most important results brought by high resolution imaging of the UV aurorae at Jupiter is the realization that there isn’t such a thing as «the aurora» at Jupiter; as these light emissions appear to arise from a variety of processes. Some are related to the interaction of the magnetospheric plasma with the moons (the satellite footprints). Others are linked with the radial motion of flux tubes through centrifugal instabilities (the injection auroral signatures). Some diffuse emissions are connected with wave-particle interaction (the equatorward diffuse emissions). Another feature is associated with the magnetosphere-ionosphere coupling (the main emission/oval). Some auroral spots are related to internally driven reconnection (the polar dawn spots). Finally, the polar-most emissions remain to be understood and this list is still incomplete. In order to illustrate the discrepancies between these various features, I will show a set of recent results derived from the analysis of Hubble Space Telescope observations. For example, I will compare the vertical profile of satellite footprints and the main emissions, and show that the energy population of the precipitating particles varies from feature to feature. Moreover, even within a single feature, spatial variations do exist. As an example, I will characterize the dawn-dusk brightness discrepancy of the main emissions and discuss its implication regarding the magnetospheric currents. And finally, the dynamics of the features also helps differentiating one type of aurora from another. This will be shown through the description of the morphological evolution of the transient flares in the polar region. [less ▲]

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See detailChallenges of Sustainable and Commercial Aquaponics
Goddek, Simon; Delaide, Boris ULg; Mankasingh, Utra et al

in Sustainability (2015), 7

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See detailImproved spectral fitting of nitrogen dioxide from OMI in the 405-465 nm window
van Geffen, J H G M; Boersma, K F; Van Roozendael, M et al

in Atmospheric Measurement Techniques (2015), 8

An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA’s EOS-Aura ... [more ▼]

An improved nitrogen dioxide (NO2) slant column density retrieval for the Ozone Monitoring Instrument (OMI) in the 405–465 nm spectral region is presented. Since the launch of OMI on board NASA’s EOS-Aura satellite in 2004, differential optical absorption spectroscopy (DOAS) retrievals of NO2 slant column densities have been the starting point for the KNMI DOMINO and NASA SP NO2 vertical column data as well as the OMI NO2 data of some other institutes. However, recent intercomparisons between NO2 retrievals from OMI and other UV/Vis and limb spectrometers, as well as ground-based measurements, suggest that OMI stratospheric NO2 is biased high. This study revises and, for the first time, fully documents the OMI NO2 retrieval in detail. The representation of the OMI slit function to convolve high-resolution reference spectra onto the relevant spectral grid is improved. The window used for the wavelength calibration is optimised, leading to much-reduced fitting errors. Ozone and water vapour spectra used in the fit are updated, reflecting the recently improved knowledge of their absorption cross section in the literature. The improved spectral fit also accounts for absorption by the O2–O2 collision complex and by liquid water over clearwater areas. The main changes in the improved spectral fitting result from the updates related to the wavelength calibration: the RMS error of the fit is reduced by 23% and the NO2 slant column by 0.85 1015 molec cm-2, independent of latitude, solar zenith angle and NO2 value. Including O2–O2 and liquid water absorption and updating the O3 and water vapour cross-section spectra further reduces NO2 slant columns on average by 0.35 1015 molec cm-2, accompanied by a further 9% reduction in the RMS error of the fit. The improved OMI NO2 slant columns are consistent with independent NO2 retrievals from other instruments to within a range that can be explained by photochemically driven diurnal increases in stratospheric NO2 and by small differences in fitting window and approach. The revisions indicate that current OMI NO2 slant columns suffered mostly from an additive positive offset, which is removed by the improved wavelength calibration and representation of the OMI slit function. It is therefore anticipated that the improved NO2 slant columns are most important to retrievals of spatially homogeneous stratospheric NO2 rather than to heterogeneous tropospheric NO2. [less ▲]

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See detailScrivere il compromesso intorno al 1965
Curreri, Luciano ULg

Article for general public (2015)

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See detailTree models with Scikit-Learn: Great models with little assumptions
Louppe, Gilles ULg

Conference (2015, April 03)

This talk gives an introduction to tree-based methods, both from a theoretical and practical point of view. It covers decision trees, random forests and boosting estimators, along with concrete examples ... [more ▼]

This talk gives an introduction to tree-based methods, both from a theoretical and practical point of view. It covers decision trees, random forests and boosting estimators, along with concrete examples based on Scikit-Learn about how they work, when they work and why they work. [less ▲]

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See detailQuand la science se mêle de la gestion des eaux pluviales : Les services écosystémiques rendus par l'infrastructure verte
Maréchal, Justine ULg

Conference given outside the academic context (2015)

L'infrastructure verte joue un rôle dominant dans nos villes. Que ce soit d'un point de vue économique, environnemental ou social, chaque fois, cette infrastructure se révèle d'une importance cruciale. La ... [more ▼]

L'infrastructure verte joue un rôle dominant dans nos villes. Que ce soit d'un point de vue économique, environnemental ou social, chaque fois, cette infrastructure se révèle d'une importance cruciale. La présentation s'intéressera dans un premier temps à comprendre les caractéristiques de cette infrastructure verte dans différentes villes belges. Dans un deuxième temps, un parallèle sera fait entre cette structure spatiale des espaces verts et un processus écologique bien précis : la gestion de l'eau pluviale. Pour aborder cette partie, une synthèse de différentes techniques d'aménagement du paysage seront présentées en tant que pistes de réflexion pour une gestion plus intégrée de l'eau de pluie en ville. [less ▲]

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