Publications of Matthias Vanmaercke
Bookmark and Share    
Full Text
See detailSediment yield and reservoir siltation in Tigray, Ethiopia
Vanmaercke, Matthias ULiege; Hargeweyn, Nigussie; Zenebe, Amanuel et al

in Nyssen, Jan (Ed.) Geo-Trekking in Ethiopia’s Tropical Mountains - The Dogu’a Tembien District (in press)

Detailed reference viewed: 18 (3 ULiège)
Full Text
See detailThe Giba, Tanqwa and Tsaliet rivers in the headwaters of the Tekezze basin
Zenebe, Amanuel; Vanmaercke, Matthias ULiege; Guyassa, Eteffa et al

in Nyssen, Jan (Ed.) Geo-Trekking in Ethiopia’s Tropical Mountains - The Dogu’a Tembien District (in press)

Detailed reference viewed: 19 (1 ULiège)
See detailLandslide susceptibility in Africa and the Mt Elgon region
Poesen, Jean; Broeckx, Jente; Vanmaercke, Matthias ULiege

Conference (2018)

Detailed reference viewed: 17 (1 ULiège)
Full Text
See detailA data-based landslide susceptibility map of Africa
Broeckx, J.; Vanmaercke, Matthias ULiege; Duchateau, R. et al

in Earth-Science Reviews (2018), 185

Our understanding of the spatial patterns of landslides in Africa is limited with available landslide studies typically focusing on only one or a few study areas. Moreover, Africa is clearly ... [more ▼]

Our understanding of the spatial patterns of landslides in Africa is limited with available landslide studies typically focusing on only one or a few study areas. Moreover, Africa is clearly underrepresented in terms of available landslide inventories. This study aims to produce a first continent-wide landslide susceptibility map for Africa, calibrated with a well-distributed landslide dataset. We reviewed the literature on landslides in Africa and compiled all available landslide inventories (ca. 10,800 landslides), supplemented by additional landslide mapping using Google Earth imagery in underrepresented regions (ca. 7250 landslides). This resulted in a dataset of approximately 18,050 landslides. Various environmental variables were investigated for their significance in explaining the observed spatial patterns of landslides. To account for potential mapping biases in the dataset, we used Monte Carlo simulations that selected different subsets of mapped landslides to test the significance of the considered environmental variables. Based on these analyses, we constructed two landslide susceptibility maps for Africa: one for all landslide types and one excluding the known rockfalls. In both maps, topography is by far the most significant variable. We evaluated the performance of the fitted multiple logistic regression models using independent subsets of landslides, selected from the total dataset. Overall, both maps perform very well in predicting intra-continental patterns of landslides in Africa and explain about 80% of the observed variance in landslide occurrence. To further test the robustness and sensitivity to mapping biases, we also modelled landslide susceptibility while excluding regions with arid climates, as landslides in these environments are expected to be better preserved over time and therefore likely relatively overrepresented. Despite this potential bias, the effect on the landslide susceptibility model is limited. Based on the constructed database and our analyses we further discuss potential research gaps for landslide prediction in Africa and at continental scales. For example, analysis of the African countries’ mean landslide susceptibility shows a lack of landslide research in various countries prone to landsliding (e.g.: Guinea, Gabon, Lesotho, Madagascar). Apart from the intrinsic value of this landslide susceptibility map as a natural hazard risk management tool, the map and compiled database are highly promising for other applications. For example, we explored the potential significance of landslides as a geomorphic process by confronting our landslide susceptibility map with an available database of measured catchment sediment yield for 500 rivers in Africa. Overall, a significant positive, but relatively weak relation between landslide susceptibility and sediment yield is observed. © 2018 Elsevier B.V. [less ▲]

Detailed reference viewed: 72 (3 ULiège)
See detailAnalysis of past an projkected future land use change and its impact on sediment fluxes in the Rwizi catchment
Twongyirwe, Ronald; Opio, Alfons; Van Rompaey, Anton et al

Conference (2018)

Detailed reference viewed: 21 (1 ULiège)
See detailGully erosion and its impacts: some examples
Vanmaercke, Matthias ULiege; Makanzu Imwanga, Fils; Dewitte, Olivier et al

Poster (2018)

Detailed reference viewed: 32 (4 ULiège)
Full Text
See detailMapping and spatial-temporal assessment of gully density in the Middle Volga region, Russia
Golosov, Valentin; Yermolaev, Oleg; Rysin, Ivan et al

in Earth Surface Processes and Landforms (2018)

Detailed reference viewed: 27 (3 ULiège)
Full Text
See detailModelling Farm Growth and Its Impact on Agricultural Land Use: A Country Scale Application of an Agent-Based Model
Beckers, Veronique; Beckers, Jeroen; Vanmaercke, Matthias ULiege et al

in Land (2018), 7(3),

Detailed reference viewed: 20 (1 ULiège)
See detailPrevention and Mitigation of Urban Gullies: Lessons learned from Failures and Successes
Vanmaercke, Matthias ULiege; Makanzu Imwangana, Fils; Cogels, Serge et al

Conference (2018)

Detailed reference viewed: 14 (2 ULiège)
Full Text
See detailPrevention and Mitigation of Urban Gullies: Lessons learned from Failures and Successes
Vanmaercke, Matthias ULiege; Makanzu Imwangana, Fils; Cogels, Serge et al

Poster (2018)

Detailed reference viewed: 12 (1 ULiège)
Full Text
See detailDetermining RUSLE P- and C-factors for stone bunds and trenches in rangeland and cropland, North Ethiopia
Taye, G.; Vanmaercke, Matthias ULiege; Poesen, J. et al

in Land Degradation and Development (2018), 29(3), 812-824

The implementation of soil and water conservation (SWC) measures in the Ethiopian Highlands is a top priority to reduce soil erosion rates. However, the effectiveness of these measures for different ... [more ▼]

The implementation of soil and water conservation (SWC) measures in the Ethiopian Highlands is a top priority to reduce soil erosion rates. However, the effectiveness of these measures for different hillslope gradients and land use conditions remains poorly understood. This study addresses this knowledge gap by determining support practice (P) and cover-management (C) factors of the Revised Universal Soil Loss Equation for commonly used SWC structures in semi-arid environments. The factor values were calculated on the basis of soil loss data collected with 21 large runoff plots installed in rangeland and cropland sites. The P- and C-factors were calculated following the recommended procedures. Results show P-factors ranging from 0.32 to 0.74 for stone bunds, from 0.07 to 0.65 for trenches, and from 0.03 to 0.22 for stone bunds with trenches. Reduced storage capacities due to sediment deposition resulted in significant declines of the effectiveness of SWC structures over time. For example, the average P-factor value for trenches increased from 0.1 in the first year after installation to 0.51 after 3 years. C-factor values ranged from 0.23 to 0.82 in rangeland and from 0.03 to 0.35 in cropland. For rangeland, this large variability is due to vegetation cover changes caused by grazing. In cropland, C-factors vary with crop types and tillage practices. The results of this study not only aid in modelling and quantifying the short-term impacts of SWC structures on soil erosion rates but also highlight the importance of considering temporal variations of the effectiveness of SWC measures. Copyright © 2017 John Wiley & Sons, Ltd. [less ▲]

Detailed reference viewed: 28 (2 ULiège)
See detailLandslide susceptibility and rates in the Mount Elgon region, Uganda
Broeckx, Jente; Maertens, Michiel; Isabirye, Moses et al

Conference (2018)

Detailed reference viewed: 22 (1 ULiège)
Full Text
See detailLandslide susceptibility and mobilization rates in the Mount Elgon region, Uganda
Broeckx, Jente; Maertens, Michiel; Isabirye, Moses et al

in Landslides (2018)

Detailed reference viewed: 29 (5 ULiège)
See detailA landslide susceptibility map of Africa
Broeckx, Jente; Vanmaercke, Matthias ULiege; Duchateau, Rica et al

Conference (2017, April 28)

Studies on landslide risks and fatalities indicate that landslides are a global threat to humans, infrastructure and the environment, certainly in Africa. Nonetheless our understanding of the spatial ... [more ▼]

Studies on landslide risks and fatalities indicate that landslides are a global threat to humans, infrastructure and the environment, certainly in Africa. Nonetheless our understanding of the spatial patterns of landslides and rockfalls on this continent is very limited. Also in global landslide susceptibility maps, Africa is mostly underrepresented in the inventories used to construct these maps. As a result, predicted landslide susceptibilities remain subject to very large uncertainties. This research aims to produce a first continent-wide landslide susceptibility map for Africa, calibrated with a well-distributed landslide dataset. As a first step, we compiled all available landslide inventories for Africa. This data was supplemented by additional landslide mapping with Google Earth in underrepresented regions. This way, we compiled 60 landslide inventories from the literature (ca. 11000 landslides) and an additional 6500 landslides through mapping in Google Earth (including 1500 rockfalls). Various environmental variables such as slope, lithology, soil characteristics, land use, precipitation and seismic activity, were investigated for their significance in explaining the observed spatial patterns of landslides. To account for potential mapping biases in our dataset, we used Monte Carlo simulations that selected different subsets of mapped landslides, tested the significance of the considered environmental variables and evaluated the performance of the fitted multiple logistic regression model against another subset of mapped landslides. Based on these analyses, we constructed two landslide susceptibility maps for Africa: one for all landslide types and one excluding rockfalls. In both maps, topography, lithology and seismic activity were the most significant variables. The latter factor may be surprising, given the overall limited degree of seismicity in Africa. However, its significance indicates that frequent seismic events may serve as in important preparatory factor for landslides. This finding concurs with several other recent studies. Rainfall explains a significant, but limited part of the observed landslide pattern and becomes insignificant when also rockfalls are considered. This may be explained by the fact that a significant fraction of the mapped rockfalls occurred in the Sahara desert. Overall, both maps perform well in predicting intra-continental patterns of mass movements in Africa and explain about 80% of the observed variance in landslide occurrence. As a result, these maps may be a valuable tool for planning and risk reduction strategies. [less ▲]

Detailed reference viewed: 63 (7 ULiège)
See detailPredicting gully densities at sub-continental scales: a case study for the Horn of Africa
Vanmaercke, Matthias ULiege; Pelckmans, Ignace; Poesen, Jean

Conference (2017, April 25)

Gully erosion is a major cause of land degradation in many regions, due to its negative impacts on catchment hydrology, its associated losses of land and damage to infrastructure, as well as its often ... [more ▼]

Gully erosion is a major cause of land degradation in many regions, due to its negative impacts on catchment hydrology, its associated losses of land and damage to infrastructure, as well as its often major contributions to catchment sediment yields. Mitigation and prevention of gully erosion requires a good knowledge of its spatial patterns and controlling factors. However, our ability to simulate or predict this process remains currently very limited. This is especially the case for the regional scale. Whereas detailed case studies have provided important insights into the drivers of gully erosion at local scales, these findings are often difficult to upscale to larger regions. Here we utilized a simple and cheap method to predict patterns of gully density at the sub-continental scale. By means of a random sampling procedure, we mapped gully densities for over sixty study sites across the Horn of Africa, using freely available Google Earth imagery. Next, we statistically analyzed which factors best explained the observed variation in mapped gully density. Based on these findings, we constructed a multiple regression model that simulates gully density, based on topography (average slope), soil characteristics (percentage silt) and land use (NDVI-value). Although our model could benefit from further refinement, it succeeds already fairly well in simulating the patterns of gully density at sub-continental scales. Over 75% of the predicted gully densities differ less than 5% from the observed gully density, while over 90% of the predictions deviate less than 10%. Exploration of our results further showed that this methodology may be highly useful to quantify total gully erosion rates at regional and continental scales as well as the contribution of gully erosion to catchment sediment yields. [less ▲]

Detailed reference viewed: 36 (2 ULiège)
Full Text
See detailGeomorphic and Hydrological challenges in Africa: implications for soil and water conservation
Vanmaercke, Matthias ULiege; Poesen, Jean

Conference (2017, April 24)

Expected scenarios of climate change and population growth confront Africa with various important challenges related to food, water and energy security. Many of these challenges are closely linked to the ... [more ▼]

Expected scenarios of climate change and population growth confront Africa with various important challenges related to food, water and energy security. Many of these challenges are closely linked to the impacts of soil erosion and other geomorphic processes, such as reduced crop yields, sedimentation of reservoirs and reduced freshwater quality. Despite the urgency and extent of many of these challenges, the causes and dynamics of these processes and their impacts remain severely understudied. This becomes apparent when the availability of e.g. soil erosion and catchment sediment export measurements for Africa is compared to that of other continents. Nonetheless, a substantial amount of geomorphic research has been conducted in Africa. Many of this work dates back from several decades ago, and were often only reported in ‘gray literature’ (e.g. internal reports). Here we present an overview of our current state of knowledge on soil erosion and its implications in Africa. We discuss which geomorphic process rate measurements are currently available and what can be learned from these with respect to the challenged raised above. We especially focus on our current understanding about the effectiveness of soil and water conservation techniques at various spatial and temporal scales. Based on specific case-studies (e.g. in Ethiopia and Uganda) and a meta-analysis of previous work, we highlight some research gaps, research needs and research opportunities when aiming to use Africa’s soil and water resources sustainably and efficiently [less ▲]

Detailed reference viewed: 30 (5 ULiège)
See detailDetermining RUSLE P-factors for stonebunds and trenches in rangeland and cropland, Northern Ethiopia
Taye, Gebeyehu; Poesen, Jean; Vanmaercke, Matthias ULiege et al

Conference (2017, April 24)

The implementation of soil and water conservation (SWC) measures in the Ethiopian highlands is a top priority to reduce soil erosion rates and to enhance the sustainability of agroecosystem. Nonetheless ... [more ▼]

The implementation of soil and water conservation (SWC) measures in the Ethiopian highlands is a top priority to reduce soil erosion rates and to enhance the sustainability of agroecosystem. Nonetheless, the effectiveness of many of these measures for different hillslope and land use conditions remains currently poorly understood. As a result, the overall effects of these measures at regional or catchment scale remain hard to quantify. This study addresses this knowledge gap by determining the cover-management (C) and support practice (P) factors of the Revised Universal Soil Loss Equation (RUSLE), for commonly used SWC measures in semi-arid environments (i.e. stone bunds, trenches and a combination of both). Calculations were based on soil loss data collected with runoff plots in Tigray, northern Ethiopia (i.e. 21 runoff plots of 600 to 1000 m2 , monitored during 2010, 2011 and 2012). The runoff plots were installed in rangeland and cropland sites corresponding to a gentle (5%), medium (12%) and steep (16%) slope gradients. The C and P factors of the RUSLE were calculated following the recommended standard procedures. Results show that the C-factor for rangeland ranges from 0.31 to 0.98 and from 0.06 to 0.39 for cropland. For rangeland, this large variability is due to variations in vegetation cover caused by grazing. In cropland, C-factors vary with tillage practices and crop types. The calculated P-factors ranged from 0.32 to 0.74 for stone bunds, from 0.07 to 0.65 for trenches and from 0.03 to 0.22 for a combination of both stone bunds and trenches. This variability is partly due to variations in the density of the implemented measures in relation to land use (cropland vs rangeland) and slope angles. However, also annual variations in P factor values are highly significant. Especially trenches showed a very significant decline of effectiveness over time, which is attributable to their reduced static storage capacity as a result of sediment deposition (e.g. for trenches in rangeland: 0.07-0.13 in 2010 to 0.37-0.65 in 2012). Hence, the results of this work may not only help in better modelling and quantifying the average long-term impacts of SWC measures over larger areas, but also show the importance of considering temporal variations of the effectiveness of SWC measures. [less ▲]

Detailed reference viewed: 42 (1 ULiège)