A synthesis of early and middle Holocene coastal changes in the western Belgian lowlands

A large-scale pattern of Holocene coastal evolution of the western Belgian coastal plain has been reconstructed by means of a series of palaeogeographical maps at 9 time slices between 9.5 and 6 cal. ka BP together with schematical cross-sections of the vertical sediment accumulation. The time-depth estimate and the spatial extension of the palaeo-environments is based on the relative sea-level (RSL) curve and radiocarbon dates of (basal and intercalated) peats and shells. This paper describes the methodology of reconstructing the pre-Holocene surface and asserts that the morphology of the flooded surface is a controlling factor in the distribution of the Holocene sediments. For a better visualization of the rather weak relief, a 3D terrain model is presented. The coastal evolution is further controlled by the changes in the rate of RSL rise and sediment budget. The period before ca. 7.500 cal BP is marked by a rapid RSL rise and consequently by a progressive rapid landward migration of all depositional environments as well as a major vertical sediment accretion. In the period following the first substantial decrease in the rate of RSL rise, the direct impact of the latter is subordinate to the effect of sediment budget which is in balance with the creation of accommodation space. This resulted in the sedimentary infilling of the tidal basin and the deposition of tidal clastic sediments with peat accumulation.Een groot-schalige reconstructie van de Holocene kustevolutie voor het westelijke deel van de Belgische kustvlakte wordt voorgesteld door middel van 9 paleogeografische kaarten voor de periode tussen 9.5 en 6 cal ka BP, samen met schematische doorsneden van de vertikale sediment accumulatie in de tijd. De tijd en plaats bepaling van de paleomilieus is gebaseerd op de relatieve zeespiegelcurve en radiokoolstof dateringen van veen (basis- en verlandingsveen) en schelpen. Deze studie beschrijft uitvoerig de methodologie voor de reconstructie van het pre-Holoceen oppervlak. De morfologie van dit oppervlak is een bepalende factor bij de verspreiding van de Holocene sedimenten. Een 3D terrein model geeft een duidelijk beeld van het tamelijk zwakke reliëf van het oorspronkelijke Pleistocene oppervlak. De kustevolutie is mede bepaald door de snelheid van de zeespiegelstijging en het sediment budget. De aanvankelijk vlugge zeespiegelstijging in de periode voor ca. 7500 cal BP veroorzaakte een vlugge verschuiving van de sedimentaire afzettingsmilieus landinwaarts samen met een belangrijke vertikale opvulling. Een vertraging van de snelheid van de zeespiegelstijging in de daaropvolgende periode resulteerde in een verminderde invloed van de relatieve zeespiegelstijging ten opzichte van de invloed van het sediment budget dat in evenwicht was met de bergingsruimte. Daardoor kon het getijdengebied volledig opgevuld worden met clastische sedimenten afwisselend met verlandingsvenen

Ground Deformations Observed for Three Decades (1992-2022) above Old and Deep Coal Mines Reused for Deep Gas Storage Sites (Wallonia, Belgium) Using PS-InSAR Time-Series

peer reviewedThe exploitations of the coal mines in Wallonia (Belgium) were ceased progressively till the year 1984. Groundwater pumping activities were stopped inducing a progressive groundwater rebound affecting different areas with different rates but still visible today with radar interferometry. To mitigate the threats to the environment during the postmining period, flooding and outbreak risks, surface ground deformations and the stability of civil engineering infrastructures in the vicinity of those mined areas need to be monitored. The persistent scatterer radar interferometry technique (PS-InSAR) revealed ground displacements during three decades above the two underground reservoirs (Peronnes to the West and Anderlues to the East) used for gas extraction and storage south of La Louvière city (Wallonia). 236 Interferograms were produced using images acquired by the ESA's satellites (ERS1/2, ENVISAT, and Sentinel-1A). Land surface displacements trends are heterogeneous both in time and space with different behaviours. During ERS1/2 (1992-2002) an uplift is visible in the western part of the Peronnes reservoir while the eastern part is still affected by subsidence while the Anderlues reservoir is affected by global subsidence. During ENVISAT (2003-2010), the uplifting conditions were stronger in the Peronnes reservoir and only the upper right corner is still affected by subsidence while the Anderlues reservoir records still a general subsidence phenomenon. The most recent data from Sentinel-1A revealed a general uplift through the Peronnes reservoir with decreasing LOS velocity towards the north and the south. The Anderlues reservoir is still affected by a subsidence phenomenon, but the LOS velocity values are reduced compared to the previous decades.monitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements15. Life on lan

Ground Deformations Related to an Old Drainage Adit in The Abandoned Coal Concession Around Saint-Vaast (Wallonia, Belgium) Analyzed Using PS InSAR and Piezometric Wells Time Serie

peer reviewedmonitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements15. Life on lan

Land subsidence as revealed by PS-InSAR observations in the Antwerp area (Belgium): first steps towards the understanding and modelling

PS-InSAR observations using multi-sensor radar data acquired by ERS 1-2, ENVISAT ASAR, and Sentinel-1A satellite sensors operating in C-band, have shown various land subsidence rates in different zones of the Antwerp area along the Scheldt River and in the harbor zone during the 1992 to 2021 period1. The LOS velocity values calculated from different radar datasets collected over Antwerp City Centre are ranged between -0.96 - +1.14 mm/year (ERS 1-2), -2.21 - +1.11 mm/year (ENVISAT), and -3.31 - +3.87 mm/year (Sentinel-1A). Moreover, the LOS velocity values for Antwerp Harbor are -4.38 - +1.02, -4.06 - +1.65, and -9.46 - +3.86 which are more significant than their corresponding ranges in the Antwerp City Centre. Groundwater is intensively pumped from the sandy Vlaanderen Formation (Holocene), Lillo and Poederlee Formations (Pliocene), and Berchem Formation (Miocene). However, in this area, land subsidence can be attributed to four potentially complementary consolidation processes: - natural consolidation of the Holocene estuarine sediments, - additional consolidation in the saturated Holocene estuarine sediments due to the backfill overload (8 m thick embankments) along the harbor docks, - saturated-unsaturated consolidation of the backfill materials, - consolidation of the most compressible layers, probably in the Boom Formation (Paleocene) and in the Asse clay of the Maldegem Formation (Eocene) due to pore pressure decrease induced by groundwater pumping in the different Cenozoic aquifers. Indeed, several of these processes could be added to produce the actual observed land subsidence. Geomechanical and hydrogeological data were being collected in the frame of the BESLSPO BRAIN project: "monitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements (LASUGEO)". For consolidation of estuarine sediments induced by the backfill overload, the rapid increase of total stress should be equilibrated by an increase of both water pore pressure and effective stress. This later, inducing land subsidence, will progressively increase as the water overpressure can be dissipated mostly laterally through groundwater flow. A coupled approach including a 3D groundwater flow model and 1D geomechanical models will be needed for a detailed analysis2,3,4. First, local models will probably be needed in specific zones to understand in detail the ongoing consolidation processes. Then a large 3D groundwater flow model will be considered over the Antwerp area including all the complex boundary conditions with the Scheldt River and the harbor docks to provide realistic transient water pressure conditions to numerous 1D geomechanical models in the area.LASUGE

Soil settlement and uplift damage to architectural heritage structures in Belgium: country-scale results from an InSAR-based analysis

Soil movement may be induced by a wide variety of natural and anthropogenic causes, which are detectable in the local scale, but may influence the movement of the soil over vast geographical expanses. Space borne interferometric synthetic aperture radar (InSAR) measurements of ground movement provide a method for the remote sensing of soil settlement and uplift over wide geographic areas. Based on this settlement and uplift evaluation, the assessment of the potential damage to architectural heritage structures is possible. In this paper an interdisciplinary monitoring and analysis method is presented that processes satellite, cadastral, patrimonial and building geometry data, used for the calculation of settlement and uplift damage to architectural heritage structures in Belgium. It uses processed InSAR data for the determination of the soil movement profile around each case study, of which the typology is determined from patrimonial information databases and the geometry is calculated from digital elevation models. The impact on the historic structures is calculated from the determined soil movement profile based on various soil-structure interaction models for buildings. The Declercqresulting damage is presented in terms of a numerical index illustrating its severity according to different criteria. In this way the potential soil movement damage is quantified in a large number of buildings in an easily interpretable and user-friendly fashion. The processing of InSAR data collected over the previous 3 decades allows the determination of the progress of settlement- and uplift-induced damage in this time period. With the integration of newly acquired and more accurate data, the methodology will continue to produce results in the coming years, both for the evaluation of soil settlement and uplift in Belgium as for introducing related damage risk data for existing architectural heritage buildings. Results of the analysis chain are presented in terms of potential current damage for selected areas and buildings.The authors wish to acknowledge the funding received by BRAIN.be, BelSPO in support of the GEPATAR research project (“GEotechnical and Patrimonial Archives Toolbox for ARchitectural conservation in Belgium” BR/132/A6/Gepatar)Peer ReviewedPostprint (published version

Post Mining Ground Deformations Transition Related to Coal Mines Closure in the Campine Coal Basin, Belgium, Evidenced by Three Decades of MT-InSAR Data

peer reviewedSpatio-temporal ground-movement measurements and mappings have been carried out in the Campine coalfield in Belgian Limburg since the closure of the mines to document post-mining effects. MT-InSAR measurements are compared to groundwater head changes in the overburden and to height data from the closest GNSS stations. Radar interferometry is used to estimate the extension and the velocity of ground movements. In particular, the MT-InSAR technique has been applied to SAR acquisitions of the satellites ERS-1/2 (1991–2005), ENVISAT (2003–2010), COSMO-SkyMed (2011–2014), and Sentinel-1A (2014–2022). The images were processed and used to highlight a switch from subsidence to uplift conditions in the western part of the coal basin, while the eastern part had already been affected by a rebound since the beginning of the ERS-1/2 acquisitions. Following the closure of the last active colliery of Zolder in 1992 and the subsequent cease of mine-water pumping, a recharge of mine-water aquifers occurred in the western part of the basin. This process provoked the change from subsidence to uplift conditions that was recorded during the ENVISAT period. In the center of the coal-mining area, measured uplift velocities reached a maximum of 18 mm/year during the ENVISAT period, while they subsided at -12 mm/year during the ERS-1/2 period. Mean velocities in the western and eastern parts of the coalfield area have decreased since the last MT-InSAR measurements were performed using Sentinel-1A, while the Zolder coal mine continues to rise at a faster-than-average rate of a maximum of 16 mm/year. The eastern part of the coalfield is still uplifting, while its rate has been reduced from 18 mm/year (ERS-1/2) to 9 mm/year (Sentinel-1A) since the beginning of the radar–satellite observations. Time-series data from the two GNSS stations present in the study area were used for a local comparison with the evolution of ground movements observed by MT-InSAR. Two leveling campaigns (2000, 2013) were also used to make comparisons with the MT-InSAR data. The station’s measurements and the leveling data were in line with the MT-InSAR data. Overall, major ground movements are obviously limited to an extension of the actual underground-mining works and rapidly diminish outside of them

Advanced processing of remotely sensed big data for cultural heritage conservation

Damage assessment, protection and preservation of built patrimony are a priority at national and local levels due to their importance to many cultural and economic aspects. This paper presents a methodology to estimate the potential damage caused by ground settlement for cultural heritage buildings using remotely sensed big data. Specifically, it presents a framework to assess the potential damage caused by ground settlement for masonry, infilled and bare frames structures using Persistent Scatterer Interferometric (PSI) measurements. The proposed solution advances the state-of-the-art by integrating big Earth observation (EO), environmental, architectural and historical data, for estimating the settlement induced damage to hundreds thousands of buildings. The fully automatic scheme was created within cloud computing environment for accelerating data transfer, processing and modeling and for improving the visualization of image-derived products.Peer ReviewedPostprint (author's final draft

A Step Towards Accurate Integrated Monitoring of The Sinking Zones in the Coastal Area of Antwerp Due to Possible Hydrogeological and Geomechanical Processes

peer reviewedmonitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurements15. Life on lan

Subsidence Evolution of Antwerp Region, Belgium over 77 Years, Using Historical Levelling and GNSS Data and Recent Persistent Scatterers Interferometry Observations

peer reviewedA combination of historical levelling surveys, recent Global Navigation Satellite System (GNSS) campaign, and Persistent Scatterers Interferometry (PSI) measurements reveal that the harbour of Antwerp in Belgium has been sinking for the last 77 years. By integrating recently acquired data using PSI and historic databases, this study aims to provide the longest possible time series of data coverage for ground deformation in Antwerp. All data on subsidence in the area is assessed using multiple techniques and has been coherently included in a Geographic Information System (GIS). The long-term impact of ground subsidence on the harbour potentially has both natural and human-caused sources. The oldest dataset is a map of altitude changes in Belgium, based on a comparison of two first-order levelling surveys conducted in 1946-1948 and between 1976-1980 (Pissart and Lambot, 1989). The iso-displacement map for the entire country was calculated by subtracting the elevation map of the second levelling network from the first. The harbour of Antwerp was crossed by two iso-displacement lines of -20 and -10 mm, representing the overall displacement values over 31 years. This historical data demonstrates that there was a minor sinking in the region likely linked to natural consolidation when the anthropogenic changes in the harbour had not been made. As the second dataset, three PSI datasets including ERS1/2, Envisat, and Sentinel-1A spanning the area in the periods 1991-2005, 2003-2010, and 2016-2019 respectively were collected and post-processed. The rate of subsidence in the Antwerp harbor and its city centre differs noticeably from one another, based on this data set. The average velocity of PS data in the city centre is 0.002, -0.06, and -0.6 mm/year and in the harbour is -0.83, -2.71, and -1.62 mm/year during the three time spans (Declercq et al., 2021). This study extends Sentinel-1A processing until 2022. Among the 33 permanent Real-Time Kinematic (RTK) GNSS stations, there are three available stations to monitor the deformation of the region. ANTW (ANTWerp) and ATWR (AnTWeRp) are 70 meters away from each other and both are located within the city centre, and BEZA (BErendrecht-ZAndvliet-Lillo) is in the northeast of harbour. The vertical velocities at the locations of ANTW, ATWR, and BEZA during the periods 2003-2018, 2018-present, and 2010-present, are measured as -0.5, -1.9, and –2.2 mm/year respectively. First, occurring at a rate of a sub-millimetre per year between 1946 and 1980 as measured in the levelling survey, land subsidence has recently increased substantially, reaching a maximum rate of -7 mm/year observed by the PSI technique. The previous low rate of subsidence as measured by the levelling shows that the natural consolidation of Holocene sediments probably occurred from the beginning. However, this sinking has increased recently, as shown by the most recent PSI and GNSS data. This is probably mostly a man-induced process linked to the consolidation of the constructed backfill and its underlying layer due to its overpressure, together with the consolidation of the most compressible and less permeable layers (aquitards) due to pore pressure decrease induced by groundwater pumping in the aquifers.monitoring LAnd SUbsidence caused by Groundwater exploitation through gEOdetic measurement

Natalizumab treatment shows low cumulative probabilities of confirmed disability worsening to EDSS milestones in the long-term setting.

Abstract Background Though the Expanded Disability Status Scale (EDSS) is commonly used to assess disability level in relapsing-remitting multiple sclerosis (RRMS), the criteria defining disability progression are used for patients with a wide range of baseline levels of disability in relatively short-term trials. As a result, not all EDSS changes carry the same weight in terms of future disability, and treatment benefits such as decreased risk of reaching particular disability milestones may not be reliably captured. The objectives of this analysis are to assess the probability of confirmed disability worsening to specific EDSS milestones (i.e., EDSS scores ≥3.0, ≥4.0, or ≥6.0) at 288 weeks in the Tysabri Observational Program (TOP) and to examine the impact of relapses occurring during natalizumab therapy in TOP patients who had received natalizumab for ≥24 months. Methods TOP is an ongoing, open-label, observational, prospective study of patients with RRMS in clinical practice. Enrolled patients were naive to natalizumab at treatment initiation or had received ≤3 doses at the time of enrollment. Intravenous natalizumab (300 mg) infusions were given every 4 weeks, and the EDSS was assessed at baseline and every 24 weeks during treatment. Results Of the 4161 patients enrolled in TOP with follow-up of at least 24 months, 3253 patients with available baseline EDSS scores had continued natalizumab treatment and 908 had discontinued (5.4% due to a reported lack of efficacy and 16.4% for other reasons) at the 24-month time point. Those who discontinued due to lack of efficacy had higher baseline EDSS scores (median 4.5 vs. 3.5), higher on-treatment relapse rates (0.82 vs. 0.23), and higher cumulative probabilities of EDSS worsening (16% vs. 9%) at 24 months than those completing therapy. Among 24-month completers, after approximately 5.5 years of natalizumab treatment, the cumulative probabilities of confirmed EDSS worsening by 1.0 and 2.0 points were 18.5% and 7.9%, respectively (24-week confirmation), and 13.5% and 5.3%, respectively (48-week confirmation). The risks of 24- and 48-week confirmed EDSS worsening were significantly higher in patients with on-treatment relapses than in those without relapses. An analysis of time to specific EDSS milestones showed that the probabilities of 48-week confirmed transition from EDSS scores of 0.0–2.0 to ≥3.0, 2.0–3.0 to ≥4.0, and 4.0–5.0 to ≥6.0 at week 288 in TOP were 11.1%, 11.8%, and 9.5%, respectively, with lower probabilities observed among patients without on-treatment relapses (8.1%, 8.4%, and 5.7%, respectively). Conclusions In TOP patients with a median (range) baseline EDSS score of 3.5 (0.0–9.5) who completed 24 months of natalizumab treatment, the rate of 48-week confirmed disability worsening events was below 15%; after approximately 5.5 years of natalizumab treatment, 86.5% and 94.7% of patients did not have EDSS score increases of ≥1.0 or ≥2.0 points, respectively. The presence of relapses was associated with higher rates of overall disability worsening. These results were confirmed by assessing transition to EDSS milestones. Lower rates of overall 48-week confirmed EDSS worsening and of transitioning from EDSS score 4.0–5.0 to ≥6.0 in the absence of relapses suggest that relapses remain a significant driver of disability worsening and that on-treatment relapses in natalizumab-treated patients are of prognostic importance