Recherches

Risques naturels et cartographie

Nos activités de recherche concernent les domaines de la géologie, de la géomorphologie et de l’évaluation des risques naturels. La télédétection optique, thermale et radar et les systèmes d’information géographique (SIG) sont utilisés en soutien à la recherche ainsi que dans le cadre de la réalisation de cartes thématiques.

La plupart de nos zones d’étude se situent dans le Rift est-africain (REA), un élément tectonique majeur qui façonne l’Afrique de l’Est et centrale avec de longues dépressions qui s’étirent entre des régions montagneuses, résultant de l’action de failles géologiques associées à des séismes et à du volcanisme.

Nos activités se partagent entre trois grands thèmes.

Évaluation d'aléas naturels (en anglais)

The main region of interest is located in the western branch of EAR, from Lake Tanganyika to the south, to the Rwenzori Mountains to the north. It covers eastern DR Congo, Rwanda, Burundi, and southwest Uganda

Our research focuses on volcanic, landslide, and seismic hazards. Their study involves the collection of information from geomorphology and geomorphometry, as well as information from historical and recent events (e.g. location, characteristics, time of occurrence, controlling and triggering factors). The study of the related spatio-temporal patterns at various scales allows a better understanding of the underlying processes.

To achieve our research objectives, we combine fieldwork with multi-sensor remote sensing data ranging from very high to low spatial resolution (e.g., Pléiades, CosmoSkyMed, Sentinel, TanDEM-X, TRMM, Landsat, aerial photos, and UAV). Such data are combined with a wealth of ground measurements (seismic ground based networks, GPS surveying, rain gauge networks, etc.), catalogues, digital soil and lithological maps and regional climate modelling approaches. Multidisciplinary approaches have indeed highlighted the strong potential of combined usage of different data sources for the study of these processes.

Together with our African partners, we are maintaining a scientific collaboration with a long-term perspective with the goal to develop the most appropriate study and monitoring techniques and the scientific knowhow required for adequate and realistic hazard and risk assessments in the region of investigation.

Volcanoes

The Virunga Volcanic Province is a chain of eight large volcanic edifices surrounded by hundreds of satellite cones, located between Lake Edward and Lake Kivu.

Africa’s most active volcanoes, Nyiragongo and Nyamulagira, are the source of spectacular events that are occasionally responsible for catastrophic disasters, like in 1977 and 2002, when the Nyiragongo lava flows caused destruction, death, health problems, and perennial socio-economic issues around the city of Goma. 

We have developed one of the broadest expertise over that volcanic region, and have built the largest database of scientific data on Nyiragongo and Nyamulagira, including colonial and post-colonial scientific documents (peer-reviewed articles, MSc and PhD Theses, scientific reports, field notes, photographs), satellite images, aerial photographs, ground-based monitoring records and GIS products.

Major advances in understanding Virunga volcanic activity were mostly realised thanks to radar interferometry (InSAR) and networks of ground-based instruments deployed in partnership with Luxembourg partner ECGS/MNHN. InSAR studies of the Nyiragongo 2002 eruption offered new hypotheses about rifting processes in EAR and important efforts are devoted to improving the detection of early warning signals. Modern photogrammetric techniques, merged with high resolution satellite imagery (InSAR and optics time-series), are used for the study of the Nyiragongo and Nyamulagira lava lakes and associated ground deformations within the main craters of both volcanoes. 

The extended literature review including the exploitation of colonial archives, contributes to better constraining and improving the eruptive activity history of Nyiragongo and Nyamulagira

Recent publications:

Landslides

Landslides, defined here as ‘the gravitational movement of a mass of rock, debris or earth down a slope’, include a wide range of ground movements, such as rock falls, deep failure of slopes and shallow debris flows. Landslides are the most important geohazard in terms of recurring impact on the population, causing fatalities every year and resulting in structural and functional damage to infrastructures and private properties, as well as serious disruptions of the organization of societies.

Until very recently few data were available for the western branch of the East African Rift (EAR) to estimate the hazard associated with these slope processes. Now, through the initiation of several research projects and the setting-up of methodologies for data collection adapted to this data-poor environment, it becomes possible to draw a first regional picture of the situation

Landside concentration is favoured by natural triggering and environmental factors such as heavy rainfalls, earthquake occurrences and steep topographies. In addition, anthropogenic factors such as rapid land use changes and urban expansion increase sensitivity to slope instability. Many landslides are observed each year in the whole region, and their occurrence is clearly linked to complex topographic, lithological and vegetation signatures. The majority of events are consequences of intense rainfall, although also earthquake-triggered landslides are identified.

The main research questions are on:

  • understanding of rainfall controls on landslide occurrence
  • interactions of landslides with other natural hazards
  • interplay between natural processes and human activities.

Recent publications:

Analyse de vulnérabilité et de risque (en anglais)

To better understand the potential impacts of geological hazards on society, we also focus on vulnerability and risk assessment. Our approach is based on strong partnerships with local scientists and institutions responsible for disaster prevention and risk management. In that perspective, research is based on the collaboration with a solid network of stakeholders involved in urban planning.

The followed methodology relies on extensive field work for in-depth discussions with key indicators and data collection through qualitative and quantitative surveys. Combined with remote sensing techniques – mainly high resolution optical and radar imagery – the approach is pragmatic and relevant in that area.

Urban growth, infrastructure, and population vulnerability are derived from the collected data using conceptual models which have been adapted to the specific context of Central Africa. Risk is not only tackled by assessing potential direct impacts on these assets, but also indirect impacts on the broader environment.

Recent publications:

  • Michellier, C., Pigeon, P., Kervyn, F., Wolff, E., accepted. Contextualizing vulnerability assessment: a support to geo-risk management in central Africa. Geological Society of London Special Publication Vulnerability Assessment in Natural Hazard Risk: A Dynamic Perspective.
  • Trefon, T., 2014. Congo’s Environmental Catch-22. in Reed, D. (ed.), In Pursuit of Prosperity: US Foreign Policy in the Era of Natural Resource Scarcity. Routledge, New York, ISBN-13: 978-1138791909.
  • Michellier, C., Dewitte, O., Trefois, P., Kervyn, F.,2014. Crowd-sourced natural disasters database in Central Africa for multi-risk regional assessments. RGS-IBG Annual International Conference 2014, London, UK; 26-29 August 2014.
  • Michellier, C., Kervyn, F., Wolff, E.,2014. Vulnerability in Central Africa: definition and assessment in collaboration with local institutions and scientists. RGS-IBG Annual International Conference 2014, London, UK; 26-29 August 2014.
  • Trefon, T., 2013. Uncertainty and Powerlessness in Congo 2012. Review of African Political Economy, 40, 141-151, doi: 10.1080/03056244.2013.762148. [Link]
  • Trefon, T., 2011. Urban–Rural Straddling: Conceptualizing the Peri-urban in Central Africa. Journal of Developing Societies, 27, 421–443, doi: 10.1177/0169796X1102700408.
Cartographie thématique (en anglais)

Mapping activities have two goals: provide support to our research projects and respond to specific requests. We have expertise in GIS and in thematic mapping in various sectors. Produced maps are commonly derived from the combined use of remote sensing imagery and archive, and on-purpose-collected field data.

Among recent achievements, a good example is the production, in 2014, of the digital soil maps of Burundi, at the scale of 1:50,000. That work illustrates the capitalization of archives that have been digitized from existing hard copy documents, corrected for some imperfections, and harmonized using a new up-to-date and regional soil reference legend.

Recent publications:

  • Laghmouch, M., Nkurunziza, L., Barivuma, E. Nishimagizwe, F., Ndayishimiye, V., Kervyn, F., 2015. Carte Sanitaire du Burundi au 1 / 250 000. Ministère de la Santé Publique et de la lutte Contre le Sida du Burundi & Royal Museum for Central Africa (RMCA), Tervuren, Belgium, ISBN : 978-9-4922-4411-6.
  • Laghmouch, M., Baert, G., Verdoodt, A., Van Ranst, E., Sendegeya, M., Tessens, E., Mvuyekure, E., Muganza, J.-P., Bigura, C., Kervyn, F., 2014. Carte Pédologique du Burundi au 1/50000 (42 planches). République du Burundi - Ministère de l'Agriculture - Institut des Sciences Agronomiques du Burundi & Royal Museum for Central Africa (RMCA), Tervuren, Belgium, ISBN : 9789491615580.
  • Laghmouch, M., Zenga Kubuisa J., 2014.  Carte administrative et routière du Kwango, RDC au 1/500.000 ; Royal Museum for Central Africa (RMCA), Tervuren, Belgium, ISBN : 978-9-4916-1588-7.
  • Lahogue, P., Mbolokala, D., Mees, F., Laghmouch, M., 2013. Carte géologique de Kinshasa 1/50.000. Royal Museum for Central Africa (RMCA), Tervuren, Belgium & Centre de Recherche Géologique et Minière, Kinshasa (RDC), ISBN: 978-9-4916-1507-8.
  • Laghmouch, M., Fernandez, M.A., Dewaele, S., 2012. Geological map of Kibara fold belt (1:750000), Katanga, Democratic Republic of Congo (DRC). Royal Museum for Central Africa (RMCA), Tervuren, Belgium, ISBN: 978-9-4916-1523-8.