Publications of Alain Demoulin
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See detailGeomorphic response to active tectonics: Numerical and field-based approaches
Demoulin, Alain ULiege; Schiattarella, M.; Pedersen, V. K.

in Earth Surface Processes and Landforms (2018), 43

[No abstract available]

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See detailMorphotectonics and past large earthquakes in eastern Belgium
Vanneste, K.; Camelbeeck, T.; Verbeeck, K. et al

in Demoulin, Alain (Ed.) Landscapes and landforms of Belgium and Luxembourg (2018)

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See detailLandslides in Belgium: two case studies in the Flemish Ardennes and the Pays de Herve
Dewitte, O.; Van den Eeckhaut, M.; Poesen, J. et al

in Landscapes and landforms of Belgium and Luxembourg (2018)

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See detailCharacteristics and frequency of large submarine landslides at the western tip of the Gulf of Corinth
Beckers, Arnaud; Hubert, Aurelia ULiege; Beck, Christian et al

in Natural Hazards and Earth System Sciences (2018)

Coastal and submarine landslides are frequent at the western tip of the Gulf of Corinth, where small to medium failure events (106–107 m3/ occur on average every 30–50 years. These landslides trigger ... [more ▼]

Coastal and submarine landslides are frequent at the western tip of the Gulf of Corinth, where small to medium failure events (106–107 m3/ occur on average every 30–50 years. These landslides trigger tsunamis and consequently represent a significant hazard. We use here a dense grid of high-resolution seismic profiles to realize an inventory of the large mass transport deposits (MTDs) that result from these submarine landslides. Six large mass wasting events are identified, and their associated deposits locally represent 30% of the sedimentation since 130 ka in the main western basin. In the case of a large MTD of 1 km3 volume, the simultaneous occurrence of different slope failures is inferred and suggests an earthquake triggering. However, the overall temporal distribution of MTDs would result from the time-dependent evolution of pre-conditioning factors rather than from the recurrence of external triggers. Two likely main pre-conditioning factors are (1) the reloading time of slopes, which varied with the sedimentation rate, and (2) dramatic changes in water depth and water circulation that occurred 10–12 ka ago during the last post-glacial transgression. Such sliding events likely generated large tsunami waves in the whole Gulf of Corinth, possibly larger than those reported in historical sources considering the observed volume of the MTDs. [less ▲]

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See detailErosion surfaces in the Ardenne-Oesling and their associated kaolinic weathering mantle
Demoulin, Alain ULiege; Barbier, F.; Deconinck, A. et al

in Landscapes and landforms of Belgium and Luxembourg (2018)

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See detailApplying Pattern Oriented Sampling in current fieldwork practice to enable more effective model evaluation in fluvial landscape evolution research
Briant, R. M.; Cohen, K. M.; Cordier, Stéphane et al

in Earth Surface Processes and Landforms (2018), 43

Field geologists and geomorphologists are increasingly looking to numerical modelling to understand landscape change over time, particularly in river catchments. The application of landscape evolution ... [more ▼]

Field geologists and geomorphologists are increasingly looking to numerical modelling to understand landscape change over time, particularly in river catchments. The application of landscape evolution models (LEMs) started with abstract research questions in synthetic landscapes. Now, however, studies using LEMs on real-world catchments are becoming increasingly common. This development has philosophical implications for model specification and evaluation using geological and geomorphological data, besides practical implications for fieldwork targets and strategy. The type of data produced to drive and constrain LEM simulations has very little in common with that used to calibrate and validate models operating over shorter timescales, making a new approach necessary. Here we argue that catchment fieldwork and LEM studies are best synchronized by complementing the Pattern Oriented Modelling (POM) approach of most fluvial LEMs with Pattern Oriented Sampling (POS) fieldwork approaches. POS can embrace a wide range of field data types, without overly increasing the burden of data collection. In our approach, both POM output and POS field data for a specific catchment are used to quantify key characteristics of a catchment. These are then compared to provide an evaluation of the performance of the model. Early identification of these key characteristics should be undertaken to drive focused POS data collection and POM model specification. Once models are evaluated using this POM/POS approach, conclusions drawn from LEM studies can be used with greater confidence to improve understanding of landscape change. © 2018 John Wiley & Sons, Ltd. [less ▲]

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See detailValidation of TRMM for hazard assessment in the remote context of tropical Africa
Monsieurs, Elise ULiege; Kirschbaum, Dalia; Jackson, Tan et al

in AGU Fall Meeting Abstracts (2017, December)

Accurate rainfall data is fundamental for understanding and mitigating the disastrous effects of many rainfall-triggered hazards, especially when one considers the challenges arising from climate change ... [more ▼]

Accurate rainfall data is fundamental for understanding and mitigating the disastrous effects of many rainfall-triggered hazards, especially when one considers the challenges arising from climate change and rainfall variability. In tropical Africa in particular, the sparse operational rainfall gauging network hampers the ability to understand these hazards. Satellite rainfall estimates (SRE) can therefore be of great value. Yet, rigorous validation is required to identify the uncertainties when using SRE for hazard applications. We evaluated the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 Research Derived Daily Product from 1998 to 2017, at 0.25° x 0.25° spatial and 24 h temporal resolution. The validation was done over the western branch of the East African Rift, with the perspective of regional landslide hazard assessment in mind. Even though we collected an unprecedented dataset of 47 gauges with a minimum temporal resolution of 24 h, the sparse and heterogeneous temporal coverage in a region with high rainfall variability poses challenges for validation. In addition, the discrepancy between local-scale gauge data and spatially averaged (~775 km²) TMPA data in the context of local convective storms and orographic rainfall is a crucial source of uncertainty. We adopted a flexible framework for SRE validation that fosters explorative research in a remote context. Results show that TMPA performs reasonably well during the rainy seasons for rainfall intensities <20 mm/day. TMPA systematically underestimates rainfall, but most problematic is the decreasing probability of detection of high intensity rainfalls. We suggest that landslide hazard might be efficiently assessed if we take account of the systematic biases in TMPA data and determine rainfall thresholds modulated by controls on, and uncertainties of, TMPA revealed in this study. Moreover, it is found relevant in mapping regional-scale rainfall-triggered hazards that are in any case poorly covered by the sparse available gauges. We anticipate validation of TMPA’s successor (Integrated Multi-satellitE Retrievals for Global Precipitation Measurement; ~10 km × ~10 km, half-hourly) using the proposed framework, as soon as this product will be available in early 2018 for the 1998-present period. [less ▲]

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See detailTropical Rainfall Measuring Mission validation in the western branch of the East African Rift: towards regional hazard assessment,
Monsieurs, Elise ULiege; Kirschbaum, Dalia; Maki Mateso, Jean-Claude et al

Scientific conference (2017, November)

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See detailLandslide inventory approach for regional-scale hazard assessment in a data-poor context in tropical Africa
Monsieurs, Elise ULiege; Maki Mateso, Jean-Claude; Jacobs, Liesbet et al

in Geological Society of America 2017 Meeting Abstracts (2017, October)

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See detailConstraints on Landslide-Climate Research Imposed by the Reality of Fieldwork in Central Africa
Monsieurs, Elise ULiege; Kirschbaum, Dalia B.; Thiery, Wim et al

in Association of Environmental and Engineering Geologists (CC BY-NC 4.0) (2017, June 05)

Climate change is reported to be ‘very likely’ associated with an increasing trend in extreme rainfall intensity over the tropics. Its impact on the timing of landslide initiation however remains poorly ... [more ▼]

Climate change is reported to be ‘very likely’ associated with an increasing trend in extreme rainfall intensity over the tropics. Its impact on the timing of landslide initiation however remains poorly understood. Central Africa, located in the tropics, has repeatedly been highlighted as lacking landslide catalogs and landslide-climate studies. We present a research approach, adapted to the data-poor context of Central Africa, to study regional rainfall controls on landslides conditioned by climate change. Preliminary results are presented, including a description of the current rain gauge network installed, an inventory of 83 landslide events with known date and location, and a case study of a landslide occurrence. We show that the underrepresentation of Central Africa in current landslide-climate research is related to the dearth of adequate rainfall ground monitoring networks and spatiotemporal data on landslide occurrence, rather than to the lack of landslide occurrence. Research constraints imposed by the context of Central Africa are highlighted. In presenting this challenging research setting, our aim is not to discourage research in the region, but to identify lessons learned from previous field work and emphasize the abundant opportunities inviting natural hazard studies in Central Africa. [less ▲]

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See detailIntegrated geological-geophysical models of unstable slopes in seismogenic areas in NW and SE Europe
Mreyen, Anne-Sophie ULiege; Micu, Mihai; Onaca, Alexandru et al

Poster (2017, April)

We will present a series of new integrated 3D models of landslide sites that were investigated in distinctive seismotectonic and climatic contexts: (1) along the Hockai Fault Zone in Belgium, with the ... [more ▼]

We will present a series of new integrated 3D models of landslide sites that were investigated in distinctive seismotectonic and climatic contexts: (1) along the Hockai Fault Zone in Belgium, with the 1692 Verviers Earthquake (M 6 - 6.5) as most prominent earthquake that occurred in that fault zone and (2) in the seismic region of Vrancea, Romania, where four earthquakes with Mw > 7.4 have been recorded during the last two centuries. Both sites present deep-seated failures located in more or less seismically active areas. In such areas, slope stability analyses have to take into account the possible contributions to ground failure. Our investigation methods had to be adapted to capture the deep structure as well as the physico-mechanical characteristics that influence the dynamic behaviour of the landslide body. Field surveys included electrical resistivity tomography profiles, seismic refraction profiles (analysed in terms of both seismic P-wave tomography and surface waves), ambient noise measurements to determine the soil resonance frequencies through H/V analysis, complemented by geological and geomorphic mapping. The H/V method, in particular, is more and more used for landslide investigations or sites marked by topographic relief (in addition to the more classical applications on flat sites). Results of data interpretation were compiled in 3D geological-geophysical models supported by high resolution remote sensing data of the ground surface. Data and results were not only analysed in parallel or successively; to ensure full integration of all inputs-outputs, some data fusion and geostatistical techniques were applied to establish closer links between them. Inside the 3D models, material boundaries were defined in terms of surfaces and volumes. Those models were used as inputs for 2D dynamic numerical simulations completed with the UDEC (Itasca) software. For some sites, a full back-analysis was carried out to assess the possibility of a seismic triggering of the landslides. [less ▲]

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See detailGeomorphometric dating of uplift: The case of the NW European foreland of the Alpine arc
Demoulin, Alain ULiege; Bourdon, Hadrien

Conference (2017)

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See detailFluvial archives, a valuable record of vertical crustal deformation
Demoulin, Alain ULiege; Mather, Anne; Whittaker, Alexander

in Quaternary Science Reviews (2017)

The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature ... [more ▼]

The study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms, but also for identifying the nature of crustal deformation and its history. In recent decades, geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens. Here, we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions (the effects of horizontal deformation are not addressed). Channel long profiles have received considerable attention in the literature, and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives, before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady-state characteristics. Then, we review the literature dealing with the transient response of rivers to tectonic perturbation, through the production of knickpoints propagating through the drainage network. Inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories. Finally, we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes. As well as the erosional imprint of tectonic forcing, sedimentary deposits, such as fluvial terrace staircases, are also considered as a classical component of tectonic geomorphology. We show that these studies have recently benefited from rapid advances in dating techniques, allowing more reliable reconstruction of incision histories and estimation of incision rates. The combination of progress in the understanding of transient river profiles and larger, more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation, i.e., extrapolation of local data to entire profiles. Finally, planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation. Examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the (dis)equilibrium state of drainage systems across regional drainage divides. [less ▲]

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See detailPlio-Quaternary river incision rates inferred from burial dating (Al-26/Be-10) of in cave-deposited alluvium in the Meuse catchment (E Belgium): new insights into the uplift history of the Ardennes massif
Rixhon, Gilles; Bourlès, Didier; Braucher, Régis et al

in Geophysical Research Abstracts (2017), 19

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See detailLandslide characterization from space in the Rift flanks west of Lake Kivu (DRC)
Dewitte, Olivier; Nobile, Adriano; Maki Mateso, Jean-Claude et al

Poster (2016, December 13)

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See detailGeomorphometric mapping of spatio-temporal changes in Plio-Quaternary uplift in the NW European Alpine foreland
Demoulin, Alain ULiege; Bourdon, Hadrien

in Geophysical Research Abstracts (2016), 18

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See detailA new numerical framework for simulating the control of weather and climate on the evolution of soil-mantled hillslopes
Bovy, Benoît ULiege; Braun, Jean; Demoulin, Alain ULiege

in Geomorphology (2016), 263

We present a new numerical framework for simulating short to long-term hillslope evolution. This modeling framework, to which we have given the name CLICHE (CLImate Control on Hillslope Evolution), aims ... [more ▼]

We present a new numerical framework for simulating short to long-term hillslope evolution. This modeling framework, to which we have given the name CLICHE (CLImate Control on Hillslope Evolution), aims to better capture the control of climate on soil dynamics. It allows the use of realistic forcing that involves, through a specific time discretization scheme, the variability of both the temperature and precipitation at time scales ranging from the daily rainfall events to the climatic oscillations of the Quaternary, also including seasonal variability. Two simple models of soil temperature and soil water balance permit the link between the climatic inputs and derived quantities that take part in the computation of the soil flux, such as the surface water discharge and the depth of the non-frozen soil layer. Using this framework together with a multi-process parameterization of soil transport, we apply an original method to calculate hillslope effective diffusivity as a function of climate. This allows us to demonstrate the ability of the model to simulate observed rates of hillslope erosion under different climates (cold and temperate) with a single set of parameter values. Numerical experiments furthermore suggest a potential high peak of sediment transport on hillslopes during the glacialinterglacial transitions of the Quaternary. We finally discuss the need to improve the parameterization of the soil production and transport processes in order to explicitly account for other key controlling factors that are also climate-sensitive, such as biological activity. [less ▲]

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See detailSoil production and hillslope transport in mid-latitudes during the last glacial-interglacial cycle: A combined data and modelling approach in northern Ardennes
Bovy, Benoît ULiege; Braun, Jean; Demoulin, Alain ULiege

in Earth Surface Processes and Landforms (2016), 41

The relative efficiency of various hillslope processes through Quaternary glacial–interglacial cycles in the midlatitudes is not yet well constrained. Based on a unique set of topographic and soil ... [more ▼]

The relative efficiency of various hillslope processes through Quaternary glacial–interglacial cycles in the midlatitudes is not yet well constrained. Based on a unique set of topographic and soil thickness data in the Ardennes (Belgium), we combine the new CLICHE model of climate-dependent hillslope evolution with an inversion algorithm in order to get deeper insight into the ways and timing of hillslope dynamics under one such climatic cycle. We simulate the evolution of a synthetic hill reproducing the slope, curvature, and contributing area distributions of the hillslopes of a ~ 2500km2 real area under a simple two-stage 120-kyr-long climatic scenario with linear transitions between cold and warm stages. The inversion method samples a misfit function in the model parameter space, based on estimates of the fit of topographic derivative distributions in classes of soil thickness and of the relative frequencies of the predicted soil thickness classes. Though the inversion results show remarkable convergence patterns for most parameters, no unique solution emerges.We obtain five clusters of good fits, whose centroids are taken as acceptable model solutions. Based on the predicted time series of average denudation rate and soil thickness, plus snapshots of the soil distribution at characteristic times, we discuss these solutions and, comparing them with independent data not involved in the misfit function, we identify the most realistic scenario. Beyond providing first-order estimates of several parameters that compare well with published data, our results show that denudation rates increase dramatically for a short time at both warm–cold and cold–warm transitions, when the mean annual temperature passes through the [0, 5 °C] range. We also point to the overwhelming importance of solifluction in shaping hillslopes and transporting soil, and the role of depth-dependent creep (including frost creep) throughout the climatic cycle, whereas the contributions of simple creep and overland flow are minor. [less ▲]

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