Physical Geography of North-Eastern Belgium - the Boom Clay Outcrop and Subcrop Zone
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EXTERNAL REPORT SCK•CEN-ER-202 12/Kbe/P-2 Physical geography of north-eastern Belgium - the Boom Clay outcrop and subcrop zone Koen Beerten and Bertrand Leterme SCK•CEN Contract: CO-90-08-2214-00 NIRAS/ONDRAF contract: CCHO 2009- 0940000 Research Plan Geosynthesis November, 2012 SCK•CEN PAS Boeretang 200 BE-2400 Mol Belgium EXTERNAL REPORT OF THE BELGIAN NUCLEAR RESEARCH CENTRE SCK•CEN-ER-202 12/Kbe/P-2 Physical geography of north-eastern Belgium - the Boom Clay outcrop and subcrop zone Koen Beerten and Bertrand Leterme SCK•CEN Contract: CO-90-08-2214-00 NIRAS/ONDRAF contract: CCHO 2009- 0940000 Research Plan Geosynthesis January, 2012 Status: Unclassified ISSN 1782-2335 SCK•CEN Boeretang 200 BE-2400 Mol Belgium © SCK•CEN Studiecentrum voor Kernenergie Centre d’étude de l’énergie Nucléaire Boeretang 200 BE-2400 Mol Belgium Phone +32 14 33 21 11 Fax +32 14 31 50 21 http://www.sckcen.be Contact: Knowledge Centre [email protected] COPYRIGHT RULES All property rights and copyright are reserved to SCK•CEN. In case of a contractual arrangement with SCK•CEN, the use of this information by a Third Party, or for any purpose other than for which it is intended on the basis of the contract, is not authorized. With respect to any unauthorized use, SCK•CEN makes no representation or warranty, expressed or implied, and assumes no liability as to the completeness, accuracy or usefulness of the information contained in this document, or that its use may not infringe privately owned rights. SCK•CEN, Studiecentrum voor Kernenergie/Centre d'Etude de l'Energie Nucléaire Stichting van Openbaar Nut – Fondation d'Utilité Publique ‐ Foundation of Public Utility Registered Office: Avenue Herrmann Debroux 40 – BE‐1160 BRUSSEL Operational Office: Boeretang 200 – BE‐2400 MOL 5 Abstract The Boom Clay and Ypresian clays are considered in Belgium as potential host rocks for geological disposal of high-level and/or long-lived radioactive waste. A good description and understanding of the relationship between surface variables, as there are the geomorphology, hydrography, vegetation, soils, land-use and hydrology, is needed to evaluate the past evolution and assess the future evolution of the surface environment. Changing climatic conditions (glacials and interglacials), global sea-level variations and tectonic movements (uplift and subsidence) may cause the surface environment to change profoundly during the next 1 Ma. In this report we describe the characteristics of the surface environment of the Boom Clay outcrop and subcrop zone. Starting from the present status, the palaeogeographical and palaeohydrological evolution of the Campine area is described in the framework of the Quaternary geological history of the area. Finally, an overview of possible future conditions of the surface environment is given, based on the integration of the palaeorecord and available modeling studies. 6 Table of Contents Abstract ...................................................................................................................................... 5 1 Introduction ........................................................................................................................ 7 2 General geographical characteristics .................................................................................. 8 3 Geomorphology and orohydrography .............................................................................. 10 4 Soil associations, land cover and vegetation .................................................................... 12 5 Climate and meteorology ................................................................................................. 14 6 Hydrology ......................................................................................................................... 19 6.1 Flanders ..................................................................................................................... 19 6.2 Nete catchment .......................................................................................................... 21 7 Quaternary landscape development and evolution ........................................................... 23 7.1 Introduction ............................................................................................................... 23 7.2 Climatic evolution ..................................................................................................... 24 7.2.1 Global climate evolution during the Quaternary ................................................ 24 7.2.2 Permafrost conditions in NW-Europe ................................................................ 27 7.3 Quaternary tectonic evolution of NE-Belgium .......................................................... 28 7.4 Quaternary geological and geomorphological development ..................................... 32 7.4.1 General ............................................................................................................... 32 7.4.2 The Flemish Valley ............................................................................................ 36 7.4.3 River terraces and burial history ........................................................................ 38 8 Future evolution ............................................................................................................... 39 8.1 Timeframe 0-10 ka AP .............................................................................................. 40 8.1.1 Global warming without marine transgression .................................................. 40 8.1.2 Global warming with marine transgression ....................................................... 42 8.2 Timeframe 10-50 ka AP ............................................................................................ 45 8.3 Timeframe 50-170 ka AP .......................................................................................... 46 8.4 Timeframe 170-400 ka AP ........................................................................................ 46 8.5 Timeframe 400 ka to 1 Ma AP .................................................................................. 47 9 Integration of the present status, and past and future evolution of the surface environment in the Campine area .................................................................................................................. 49 10 References ........................................................................................................................ 53 7 1 Introduction High-level and long-lived radioactive waste (B&C waste) is a major radiological hazard to man and environment. ONDRAF/NIRAS, the Belgian agency for radwaste management entitled to find a solution for this problem, currently investigates the safety and feasibility of geological disposal in poorly indurated plastic clays such as the Boom Clay and Ypresian clays. The Boom Clay is a thick and relatively homogeneous clay layer that is found in the outcrop and subcrop of a large part of north-eastern Belgium. Its thickness varies between several tens (outcrop) to more than 100 m (subcrop) while its top reaches depths of up to 200 m and more in the Campine area. The Geosynthesis project launched by ONDRAF/NIRAS in 2009 aims at bringing together all 'geological' data that demonstrate and underpin the safety and feasibility of geological disposal of category B&C waste in Boom Clay. Geological data include the geology of north-eastern Belgium, the geology of the Boom Clay, its relevant properties, the regional hydrogeological system, and the geography of north-eastern Belgium. The scope of the Geosynthesis report covers the entire Boom Clay outcrop and subcrop zone, which roughly speaking coincides with an area tentatively denoted northeastern Belgium, and/or the Campine region The earth's surface is a complex interface where atmosphere, hydrosphere, geosphere and biosphere processes interfere. In the framework of safety studies for nuclear waste disposal, the upper boundary condition governs the infiltration of precipitation (recharge) that will eventually reach deep repositories in geological layers. Similarly, discharge of groundwater eventually proceeds through soil layers into the surface environment including lakes, rivers and seepage zones. The earth's surface is also the place where biosphere receptors live and interfere with the hydrosphere and geosphere. It is clear that a solid and reliable safety analysis needs to consider aspects of the surface environment, here grouped under the name 'physical geography'. On the long-term, the surface environment will undergo important changes. With respect to a geological waste repository, the potential impact of the changing environment on the safety of such a repository should be considered. During the timeframe considered in the Geosynthesis project (up to one million years), the climate will change, as will the vegetation, soils, topography and hydrology. In this paper, the physical geography of the Boom Clay outcrop and subcrop zone in north-eastern Belgium is described in the light of the palaeogeographical and palaeohydrological evolution of the area and an assessment of the future evolution of the earth surface environment is presented. 8 2 General geographical characteristics The Campine region in northern Belgium covers about 4000 km², and is situated between the alluvial plain of the Upper Scheldt river in the west, the Meuse valley in the east and the Dijle – Demer river valleys in the south. It is a relatively