Projecten
HOMER
Geo-hydrological Hazards in the changing African trOpics: sediments, dynaMics and intERactions
The occurrence and dynamics of geo-hydrological hazards (GHH), such as shallow and deep-seated landslides, flash floods and urban gullies, is driven by complex short- and long-term interactions between climate (e.g., rainfall intensity) and landscape characteristics (e.g., geodynamical/tectonic context, lithology, vegetation patterns). In many regions, human activities such as agriculture, deforestation, mining, and urbanization are modifying these drivers alongside rapid demographic and economic shifts, exacerbating GHH frequency, intensity, and altering their spatial distribution.
GHH are typically studied in isolation, focusing primarily on their immediate socio-economic impacts, while their roles as geomorphic agents and their interactions remain much less explored. Yet, they play a key role in transferring sediment between hillslopes and river/lake systems, frequently acting as the dominant erosional process and sediment source over long timescales. This influence is further amplified by interactions between GHH (cascading or compound events), which create complex, self-reinforcing, typically positive feedback loops. For instance, material present in debris-rich flash floods is often scoured from landslides and gullies upslope; or gully formation can trigger landslides and vice versa.
In altering sediment fluxes, GHH trigger cascading effects that profoundly reshape riverine ecosystems, societies and the landscape – changes that, in turn, influences future GHH dynamics, occurrence, and ultimately, hazard. Hitherto, a comprehensive study of GHH and their interactions through their geomorphic impact is missing, because it requires i) a long-term, regional-scale perspective to capture these different, typically stochastic events, distinguish short-term variability from persistent trends, and assess the influence of natural and human-induced climatic and environmental drivers, and ii) a systematic and holistic approach that integrates data on all GHH, vegetation recovery, sediment fluxes, geochronology, machine learning and numerical modelling. Our objective is to fill this gap of understanding of the feedbacks between GHH occurrence, sediment dynamics and environmental changes with a specific focus on the African tropics, data-scarce regions where long-term records are especially missed. With its rising population and high societal vulnerability, tropical Africa is a global hotspot for both environmental changes and increasing incidence and impacts of GHH.
We hypothesize that long-term, continuous satellite time series now enable us to compile comprehensive, multi-temporal inventories of the full GHH spectrum—encompassing shallow and deep-seated landslides, flash floods, and urban gullies—and to quantify their dynamics, interactions, and cascading sediment impacts over large regions. This is made possible by over a decade of systematic, open-access data from Copernicus Sentinel sensors and state-of-the-art Earth observation workflows developed by HOMER partners through primarily STEREO-funded projects. By exploiting synergies among sensors (primarily Sentinel-1, Sentinel-2, and Sentinel-3), we will detect and track GHH occurrences and dynamics, monitor landscape vegetation recovery, and quantify sediment fluxes. Integration of these unprecedented datasets with data-driven and process-based models will reveal how GHH shape sediment fluxes and drive long-term landscape evolution, with targeted field campaigns for geochronologic sampling offering key calibration parameters for erosion rate models. By integrating these cutting-edge tools with local knowledge and field-based validation, we aim to enhance the detection, monitoring, and modelling of the full GHH spectrum at local and regional scales, ultimately generating more robust and predictive GHH models.
HOMER will yield a decadal (2016–2027) inventory of GHH occurrences, their interactions, and their impacts on sediment dynamics, refine numerical models that capture the interplay between episodic and long-term sediment processes, and deliver a transferable, optimized workflow for large-scale, continuous hazard monitoring in tropical settings. Through such an integrated, holistic approach—combining cutting-edge remote sensing tools with numerical models, local knowledge and field-based validation—HOMER seeks to fill a critical "blind spot" in geomorphology and hazard science by enhancing our understanding of key hillslope processes in typically overlooked tropical regions. Our primary objective is to clarify how the interplay between geo-hydrological hazards, sediment fluxes, and environmental changes impact landscape evolution and hazard patterns in tropical regions. Clarifying those links will help guiding mitigation measures to reduce GHH hazard, soil erosion, flood risk, and environmental degradation—ultimately benefiting public health, infrastructure, and environmental resilience in extremely vulnerable tropical regions.
Hoofdonderzoekers:
Datum:
2025 2030Medewerkers:
Externe partners:
Matthias VANMAERCKE (KU Leuven)Dimitry VAN DER ZANDE (RBINS)
Duna RODA BOLUDA (VU Amsterdam)
Benjamin CAMPFORTS (VU Amsterdam)