Democratic Republic of the Congo; Population Density; Animals; Population Dynamics; Humans; Cities/statistics & numerical data; Urban Population/statistics & numerical data; Geographic Mapping; Cities; Urban Population; Multidisciplinary
Abstract :
[en] Large urban gullies cause damage in many tropical cities across the Global South1,2. They can result from inappropriate urban planning and insufficient infrastructure to safely store and evacuate rainfall in environments that are already highly sensitive to soil erosion1,3,4. Although they can cause large destruction and societal impacts such as population displacement1,2,5, the magnitude of this geo-hydrological hazard remains poorly documented and understood6,7. Here we provide an assessment of the extent and impact of urban gullies at the scale of the Democratic Republic of the Congo (DRC). Through mapping, we identify 2,922 urban gullies across 26 cities. By combining their formation and growth rates with population density data8, we estimate that around 118,600 people (uncertainty range: ± 44,400 people) have been displaced by urban gullies over the period 2004-2023. We find that average displacement rates increased from about 4,650 persons yr-1 (pre-2020) to about 12,200 persons yr-1 (post-2020). Between 2010 and 2023, the number of people living in the potential expansion zone of urban gullies doubled from 1.6 (±0.6) to 3.2 (±1.3) million, with more likely to be exposed due to urban sprawl9,10 and climate change11. We suggest that there is a need for tools and strategies to prevent and mitigate this hazard.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Ilombe Mawe, Guy ; Université de Liège - ULiège > Sphères ; Department of Geology, Université Officielle de Bukavu, Bukavu, Democratic Republic of the Congo ; Department of Geosciences, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo
Landu, Eric Lutete; Department of Geography, University of Liège, Liège, Belgium ; Department of Geosciences, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo ; Department of Natural Resources Management, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo
Dujardin, Elise ; Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium ; Research Foundation Flanders - FWO, Brussels, Belgium
Imwangana, Fils Makanzu ; Department of Geosciences, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo ; Geomorphology and Remote Sensing Laboratory, Geological and Mining Research Center, Kinshasa, Democratic Republic of the Congo
Bielders, Charles ; Earth and Life Institute - Environnemental Sciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium
Hubert, Aurelia ; Université de Liège - ULiège > Département de géographie > Géomorphologie et Géologie du Quaternaire
Michellier, Caroline ; Earth and Life Institute - Environnemental Sciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium ; Department of Earth Sciences, Royal Museum for Central Africa, Tervuren, Belgium
Nzolang, Charles; Department of Geology, Université Officielle de Bukavu, Bukavu, Democratic Republic of the Congo
Poesen, Jean ; Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium ; Institute of Earth and Environmental Sciences, Maria-Curie Sklodowska University, Lublin, Poland
Dewitte, Olivier ; Department of Earth Sciences, Royal Museum for Central Africa, Tervuren, Belgium
Vanmaercke, Matthias ; Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium. matthias.vanmaercke@kuleuven.be
Language :
English
Title :
Mapping urban gullies in the Democratic Republic of the Congo.
This research was mainly funded through the Belgian ARES-PRD project PREMITURG (Prevention and Mitigation of Urban Gullies), which supported the PhD research of G.I.M. and E.L.L. as well as fieldwork activities. C.M. was supported by the Development Cooperation programme of the Royal Museum for Central Africa, which is supported by the Directorate-General for Development Cooperation and Humanitarian Aid of Belgium through the project HARISSA (Natural Hazards, Risks and Society in Africa: Developing Knowledge and Capacities). E.D. was supported by a PhD scholarship from the Research Foundation Flanders (FWO).
F. Makanzu Imwangana I. Vandecasteele P. Trefois P. Ozer J. Moeyersons The origin and control of mega-gullies in Kinshasa (DR Congo) Catena 125 38 49
K.C. Onyelowe The menace of the geo-environmental hazard caused by gully erosion in Abia State, Nigeria Environ. Technol. Innov. 8 343 348
J. Moeyersons F. Makanzu Imwangana O. Dewitte Site- and rainfall-specific runoff coefficients and critical rainfall for mega-gully development in Kinshasa (DR Congo) Nat. Hazards 79 203 233
G. Zolezzi M. Bezzi D. Spada E. Bozzarelli Urban gully erosion in sub-Saharan Africa: a case study from Uganda Land Degrad. Dev. 29 849 859
Kayembe Wa Kayembe, M. Ville et érosion ravinante intra-urbaine. Kinshasa: Facteurs, conséquences et interventions (L’ Harmattan, 2020).
J. Poesen Soil erosion in the Anthropocene: research needs Earth Surf. Processes Landforms 43 64 84
C.E.S. Kuhn F.A.G.V. Reis C. Zarfl P. Grathwohl Ravines and gullies, a review about impact valuation Nat. Hazards 117 597 624
Schiavina, M, Freire, S, Carioli, A, & MacManus, K. GHS-POP R2023A - GHS population grid multitemporal (1975–2030). European Commission, Joint Research Centre (JRC) https://doi.org/10.2905/2FF68A52-5B5B-4A22-8F40-C41DA8332CFE (2023).
United Nations. World Urbanization Prospects: The 2018 Revision (ST/ESA/SER.A/420) (Department of Economic and Social Affairs, Population Division, 2019).
K.C. Seto M. Fragkias B. Gu M.K.A. Reilly A meta-analysis of global urban land expansion PLoS One 6 e23777 1:CAS:528:DC%2BC3MXhtFOitr3E 21876770 3158103
D.S. Williams M. Manez Costa C. Sutherland L. Celliers J. Scheffran Vulnerability of informal settlements in the context of rapid urbanization and climate change Environ. Urban. 31 157 176
F. Bédécarrats O. Lafuente-Sampietro M. Lemenager D.L. Sowa Building commons to cope with chaotic urbanization? Performance and sustainability of decentralized water services in the outskirts of Kinshasa J. Hydrol. 573 1096 1108
Johnson, C, Jain, G. & Lavell, A. Rethinking Urban Risk and Resettlement in the Global South (UCL Press, 2021).
D. Dodman H. Leck M. Rusca S. Colenbrander African urbanisation and urbanism: implications for risk accumulation and reduction Int. J. Disaster Risk Reduct. 26 7 15
U. Ozturk et al. How climate change and unplanned urban sprawl bring more landslides Nature 608 262 265 1:CAS:528:DC%2BB38XitV2lsbfE 35941295
J. Rentschler et al. Global evidence of rapid urban growth in flood zones since 1985 Nature 622 87 92 1:CAS:528:DC%2BB3sXitVKhs73M 37794266
O. Carvalho Junior et al. Urbanization impacts upon catchment hydrology and gully development using multi-temporal digital elevation data analysis Earth Surf. Processes Landforms 35 611 617
D. Kubwimana et al. Characteristics and distribution of landslides in the populated hillslopes of Bujumbura, Burundi Geosciences 11 259
J. Nzila et al. Current dynamics of hydric erosion in the Kingouari, Mfilou and Djoué watersheds in the southwestern part of Brazzaville city (Congo) Earth Sci. 9 201 209
J. Moeyersons et al. River and landslide dynamics on the western Tanganyika rift border, Uvira, D.R. Congo: diachronic observations and a GIS inventory of traces of extreme geomorphologic activity Nat. Hazards 53 291 311
F. Makanzu Imwangana O. Dewitte M. Ntombi J. Moeyersons Topographic and road control of mega-gullies in Kinshasa (DR Congo) Geomorphology 217 131 139
M. Kayembe Wa Kayembe E. Wolff Contribution de l’approche géographique à l’étude des facteurs humains de l’érosion ravinante intra-urbaine à Kinshasa (R.D. Congo) Geo-Eco-Trop 39 119 138
J.A. Mahamba G.M. Kayitoghera M.K. Musubao G.B. Chuma W.M. Sahani Evolution of gully erosion and susceptibility factors in the urban watershed of the Kimemi (Butembo/DR Congo) Geogr. Sustain. 4 268 279
J. Poesen J. Nachtergaele G. Verstraeten C. Valentin Gully erosion and environmental change: importance and research needs Catena 50 91 133
M. Vanmaercke et al. Measuring, modelling and managing gully erosion at large scales: a state of the art Earth Sci. Rev. 218 103637
G. Ilombe Mawe et al. What controls the expansion of urban gullies in tropical environments? Lessons learned from contrasting cities in D.R. Congo Catena 241 108055
N. Gudino-Elizondo et al. Modelling ephemeral gully erosion from unpaved urban roads: equifinality and implications for scenario analysis Geosciences 8 137 30147946 6104648
E. Lutete Landu et al. The potential of runoff retention structures as a strategy to control urban gullying in tropical cities Int. Soil Water Conserv. Res. 13 217 234
Intergovernmental Panel on Climate Change (IPCC). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (eds Masson-Delmotte, V. et al.). (Cambridge Univ. Press, 2021).
O. Dewitte et al. Constraining landslide timing in a data-scarce context: from recent to very old processes in the tropical environment of the North Tanganyika-Kivu Rift region Landslides 18 161 177
M. Vanmaercke et al. How fast do gully headcuts retreat? Earth Sci. Rev. 154 336 355
C. Michellier P. Pigeon F. Kervyn E. Wolff Contextualizing vulnerability assessment: a support to geo-risk management in Central Africa Nat. Hazards 82 27 42
D. Satterthwaite et al. Building resilience to climate change in informal settlements One Earth 2 143 156
E. Lutete Landu et al. Effectiveness of measures aiming to stabilize urban gullies in tropical cities: results from field surveys across D.R. Congo Int. Soil Water Conserv. Res. 11 14 29
A. Hayas T. Vanwalleghem A. Laguna A. Peña J.V. Giráldez Reconstructing long-term gully dynamics in Mediterranean agricultural areas Hydrol. Earth Syst. Sci. 21 235 249
Pesaresi, M. et al. Atlas of the Human Planet 2017: Global Exposure to Natural Hazards (Publications Office of the European Union, 2017).
D. Smittarello et al. Precursor-free eruption triggered by edifice rupture at Nyiragongo volcano Nature 609 83 88 1:CAS:528:DC%2BB38Xit12jtrvP 36045241 9433316
A. Depicker et al. Historical dynamics of landslide risk from population and forest-cover changes in the Kivu Rift Nat. Sustain. 4 965 974
A. Dille et al. Acceleration of a large deep-seated tropical landslide due to urbanization feedbacks Nat. Geosci. 15 1048 1055 1:CAS:528:DC%2BB38XjtVGrsLzL
Lee, J.-Y. et al. in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (eds Masson-Delmotte, V. et al.) 553–672 (Cambridge Univ. Press, 2021).
N. Gudino-Elizondo et al. Rapid assessment of abrupt urban mega-gully and landslide events with structure-from-motion photogrammetric techniques validates link to water resources infrastructure failures in an urban periphery Nat. Hazards Earth Syst. Sci. 22 523 538
A. Ciampalini W. Frodella C. Margottini N. Casagli Rapid assessment of geo-hydrological hazards in Antananarivo (Madagascar) historical centre for damage prevention Geomat. Nat. Hazards Risk 10 1102 1124
J. Zscheischler et al. A typology of compound weather and climate events Nat. Rev. Earth Environ. 1 333 347
F. Gallart M. Marignani N. Pérez-Gallego E. Santi S. Maccherini Thirty years of studies on badlands, from physical to vegetational approaches. A succinct review Catena 106 4 11
R. Bartley J. Poesen S. Wilkinson M. Vanmaercke A review of the magnitude and response times for sediment yield reductions following the rehabilitation of gullied landscapes Earth Surf. Processes Landforms 24 3250 3279
A. Frankl J. Nyssen M. Vanmaercke J. Poesen Gully prevention and control: techniques, failures and effectiveness Earth Surf. Processes Landforms 46 220 238
Dodman, D. et al. in Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (Pörtner, H.-O. et al.) 907–1040 (Cambridge Univ. Press, 2022).
Dochartaigh, B. User Guide Version 1.2: Africa Groundwater Atlas Country Hydrogeology Maps. BGS Open Report OR/21/063 (British Geological Survey, 2021).
T.G. Farr et al. The Shuttle Radar Topography Mission Rev. Geophys. 45 RG2004
OCHA. Democratic Republic of the Congo - Subnational Population Statistics. HDX https://data.humdata.org/dataset/cod-ps-cod (2022).
R.N. Thwaites A.P. Brooks T.J. Pietsch J.R. Spencer What type of gully is that? The need for a classification of gullies Earth Surf. Processes Landforms 47 109 128
GEORISKA PAStECA: historical aerial photographs and archives to assess environmental changes in Central Africa, https://georiska.africamuseum.be/en/activities/completed_projects/pasteca (2021).
Jones, H. et al. Soil Atlas of Africa. European Commissionhttps://doi.org/10.2788/52319 (2013).
G. Amatulli et al. A suite of global, cross-scale topographic variables for environmental and biodiversity modeling Scientific Data 5 180040 29557978 5859920
H.E. Beck et al. Daily evaluation of 26 precipitation datasets using Stage-IV gauge-radar data for the CONUS Hydrol. Earth Syst. Sci. 23 207 224
S. De Geeter G. Verstraeten J. Poesen B. Campforts M. Vanmaercke A data driven gully head susceptibility map of Africa at 30 m resolution Environ. Res. 224 115573 36841523
P. Borrelli et al. An assessment of the global impact of 21st century land use change on soil erosion Nat. Commun. 8 2013 29222506 5722879
T. Hengl et al. African soil properties and nutrients mapped at 30 m spatial resolution using two-scale ensemble machine learning Sci. Rep. 11 1:CAS:528:DC%2BB3MXmvFGls78%3D 33731749 7969779 6130
M. Buchhorn et al. Copernicus global land cover layers—collection 2 Remote Sensing 12 1044
Ramm, F. et al. OpenStreetMap data in layered GIS format v.0.6.7 (OpenStreetMap, 2014).
McKnight, P. E. & Najab, J. Mann‐Whitney U test. in The Corsini Encyclopedia of Psychology Vol. 1, 1–10 (Wiley, 2010).
Kleinbaum, D. G., Dietz, K., Gail, M., Klein, M. & Klein, M. Logistic Regression (Springer, 2002).
S. Beguería Validation and evaluation of predictive models in hazard assessment and risk management Nat. Hazards 37 315 329
S. Leyk et al. The spatial allocation of population: a review of large-scale gridded population data products and their fitness for use Earth Syst. Sci. Data 11 1385 1409
C. Lloyd A. Sorichetta A. Tatem High resolution global gridded data for use in population studies Sci. Data 4 28140386 5283062 170001
F.R. Stevens A.E. Gaughan C. Linard A.J. Tatem Disaggregating census data for population mapping using random forests with remotely-sensed and ancillary data PLoS One 10 e0107042 25689585 4331277
P. Deville et al. Dynamic population mapping using mobile phone data Proc. Natl Acad. Sci. USA 111 15888 15893 1:CAS:528:DC%2BC2cXhvVWmsLvI 25349388 4234567
F.R. Stevens et al. Comparisons of two global built area land cover datasets in methods to disaggregate human population in eleven countries from the global South Int. J. Digital Earth 13 78 100
C. Michellier et al. Evaluating population vulnerability to volcanic risk in a data scarcity context: the case of Goma city, Virunga volcanic province (DRCongo) Int. J. Disaster Risk Reduct. 45 101460
