J. Poesen

• Prof. Dr. DSc. Dr.h.c. Em. Jean Poesen
• Professor Emeritus at KU Leuven

Africa experiences diverse and often intense soil erosion processes, yet the interplay between these processes and observed sediment yield (SY) at catchment scales is insufficiently understood. Building on previous continental-scale assessments, this study integrates a newly verified database of measured SY at 425 river outlets with, model-based es...

Subsurface erosion is a poorly recognized but important process for modelling and predicting gully erosion rates in loess areas. It is crucial to recognize the factors and mechanisms of soil piping and pipe collapse development. Our research is the first detailed description of the complex evolution of large collapsed pipes on the banks of a loess...

This report investigates the intricate interplay between the drivers of changes in soil health, along with the pressures and impacts on soil in the 32 European Environment Agency (EEA) member countries, as well as six cooperating countries from the West Balkans, Ukraine, and the UK. It sheds light on the multifaceted challenges facing soil conserva...

Following two years of combat, blockade, and power outage, the Tigray war in northern Ethiopia has had a substantial negative impact on the environment (2020–2022). This photographic dataset, part of a rare study carried out by the same research team before and after a war, compares 26-year legacy data on land degradation, with post-war observation...

The Tigray war in northern Ethiopia has had significant environmental effects on the land, after two years of fighting, blockade and power outage (2020-2022). This study contrasts post-war observations at 56 sites in Tigray’s Dogu’a Tembien district with 26-year legacy data on land degradation, a rare study conducted by the same research team befor...

This study evaluated the relation between rural-urban migration and land use changes at origin. The analysis was based on households (1015) data on their social and economic characteristics, which was used to map the spatial patterns of rural out-migration. Next, on the basis of Google-Earth imagery for 71427 ha and ground truthing, land use change...

Plant available soil moisture and its spatial variability is among the most important limiting factors for crop and livestock productivity in semi-arid Ethiopia. The objectives of this study were therefore: 1) to measure the effects of land use and slope gradient on spatial variability of topsoil moisture content. 2) to analyze the variability of t...

Wars have serious negative effects on the total environment. This study reviews 193 case studies worldwide in order to better understand these impacts and their potential management before, during and after war. The synthesis of the evidence shows that military actions damage landscape resources. Aerial bombings have great negative impacts by damag...

In this study we present a model for the global Probabilistic Hydrological Estimation of LandSlides (PHELS). PHELS estimates the daily hazard of hydrologically triggered landslides at a coarse spatial resolution of 36 km, by combining landslide susceptibility (LSS) and (percentiles of) hydrological variable(s). The latter include daily rainfall, a...

Gullies experience varying states of activity during their life cycle. For example, their highest growth rates are commonly observed in the period that follows their initiation, whereas they are less active when reaching stability. Understanding the environmental conditions under which gullies initiate, expand, and stabilize is therefore vital to m...

As a network of researchers we release an open-access database (EUSEDcollab) of water discharge and suspended sediment yield time series records collected in small to medium sized catchments in Europe. EUSEDcollab is compiled to overcome the scarcity of open-access data at relevant spatial scales for studies on runoff, soil loss by water erosion an...

Soil erosion in loess landscapes results in soil organic carbon (SOC) redistribution and storage in SOC pools. Understanding the SOC dynamics is important because changes in the SOC stocks may have impacts on global climate change. However, the topographic‐related patterns controlling SOC storage are not well understood. Closed depressions are natu...

Current widespread and intensive soil degradation in India has been driven by unprecedented levels of population growth, large‐scale industrialization, high‐yield agriculture, urban sprawl and the spread of human infrastructure. The damage caused to managed and natural systems by soil degradation threatens livelihoods and local services and leads t...

In this study we present a model for the global Probabilistic Hydrological Estimation of LandSlides (PHELS). PHELS estimates the daily hazard of hydrologically-triggered landslides at a coarse spatial resolution of 36 km, by combining landslide susceptibility (LSS) and (percentiles of) hydrological variable(s). The latter include daily rainfall, a...

Gullies experience varying states of activity during their life cycle. For example, their highest growth rates are commonly observed in the period that follows their initiation, whereas they are less active when reaching stability. Understanding the environmental conditions under which gullies initiate, expand, and stabilize is therefore vital to m...

Planning and management of water resources is crucial to enhance agricultural productivity and ensure food security in drylands. For this, adaptable and reliable runoff prediction models are urgently needed to support water harvesting and irrigation development. In this study we explored the potential of the runoff Curve Number (CN) method to estim...

Predicting gully erosion at the continental scale is challenging with current generation models. Moreover, datasets reflecting gully erosion processes are still rather scarce, especially in Africa. This study aims to bridge this gap by collecting an extensive dataset and developing a robust, empirical model that predicts gully head density at high...

Despite many years of establishment of exclosures in the semi-arid environments of north Ethiopia for rehabilitation of degraded areas, its effectiveness is constrained by water deficit. There is lack of empirical data on the response of vegetation to additional water (spate irrigation) application. This study was aimed to evaluate the effects of s...

The study and mapping of evidences of soil piping using non-destructive techniques is a key issue in quantitative geomorphology. This paper attempts to combine Aerial mapping systems (Unmanned Aerial Vehicles (UAV)), soil physical and chemical attributes, and near-surface geophysical survey tools (ground penetrating radar and electrical resistivity...

Gully erosion is the dominant process responsible for significant on-site and off-site consequences. Nevertheless, accurate gully erosion prediction is constrained by a lack of observed data on gully erosion rates and controlling factors. The occurrence and distribution of gullies can be influenced by several factors that include land use type, top...

Sustainable land management (SLM) helps maintain ecosystem functions and services and improves land productivity, while also supporting human wellbeing. The effective implementation of SLM remains a challenge because it is embedded within integrated, coevolving scientific, policy, and development pillars at both national and international levels. I...

Soil erosion by water is a major cause of land degradation in the highlands of Ethiopia and anywhere else in the world, but its magnitude and variability are rarely documented across land uses and climatological conditions. The purpose of this study was to examine runoff and soil loss responses under cropland (CL) and grazing land (GL) management p...

Sustainable land management (SLM) is widely recognized as the key to reducing rates of land degradation, and preventing desertification. Many efforts have been made worldwide by various stakeholders to adopt and/or develop various SLM practices. Nevertheless, a comprehensive review on the spatial distribution, prospects, and challenges of SLM pract...

Soil erosion is a serious threat to soil functions leading to land productivity decline and multiple off-site effects. Here we show, using a multi-model approach, the spatial risk of soil erosion by water, wind, tillage and harvesting and where the co-occurrence of these different processes is observed. Moreover, we analysed where these locations o...

Inversion tillage is a commonly applied soil cultivation practice in Europe, which often has been blamed for deteriorating topsoil stability and organic carbon (OC) content. In this study, the potential to reverse these negative effects in the topsoil by alternative agricultural management practices are evaluated in seven long-term experiments (run...

Urban gullies are a rapidly growing concern in many tropical cities of the Global South. Various measures are already implemented for their stabilization. However, an overview of these measures and their overall effectiveness is currently lacking. We aim at addressing this gap by documenting existing initiatives to stabilize urban gullies in D.R. C...

This study assesses global landslide susceptibility (LSS) at the coarse 36 km spatial resolution of global satellite soil moisture observations to prepare for a subsequent combination of a global LSS map with dynamic satellite-based soil moisture estimates for landslide modeling. Global LSS estimation contains uncertainty, arising from errors in th...

Gully erosion is a particularly damaging process which is not yet sufficiently understood and parameterized. Gully head topographic threshold relative to Hortonian runoff have been studied in cropland, rangeland and forest. This study extends such modelling approach to badlands. Different badlands (eight sites) have been studied in the Mediterranea...

Like many other lakes in the world, the interconnected Abaya and Chamo lakes in the Southern Main Ethiopian Rift are affected by rapid sediment accumulation. Although land degradation is a well-known issue in this part of the African continent, the main sediment sources, their spatial distribution and interaction in the Abaya–Chamo lakes’ basin hav...

Like many other lakes in the world, the interconnected Abaya and Chamo lakes in the Southern Main Ethiopian Rift are affected by rapid sediment accumulation. Although land degradation is a well-known issue in this part of the African continent, the main sediment sources, their spatial distribution and interaction in the Abaya–Chamo lakes’ basin hav...

We investigated water levels in semi-closed grabens of northern Ethiopia. Springs (n = 79), stream-flows (n = 48), wetlands (n = 3), endorheic lakes (n = 3), hand-dug wells (n = 48) and boreholes in unconfined aquifers (n = 25) were monitored (2015–2017). Spring discharge fluctuates between wet (2.75 ± 1.5 L/s) and dry seasons (0.87 ± 0.21 L/s) (n...

Cover management and support practices largely control the magnitude and variability of soil erosion. Although soil erosion models account for their importance (particularly by C- and P-factors in the Revised Universal Soil Loss Equation), obtaining spatially explicit quantitative field data on these factors remains challenging. Hence, also our ins...

Gully erosion is a major soil degradation process on arable land. Therefore, it is important to better understand the spatial and temporal patterns of this linear erosion process, considering the impacts of land use and climate changes. The main objective of this study was to analyze the spatial and temporal patterns of permanent gully development...

Inversion tillage is a commonly applied soil cultivation practice in Europe, which though has been blamed for deteriorating topsoil stability and organic carbon (OC) content. In this study, the potential to reverse these negative effects in the topsoil by alternative agricultural management practices are evaluated in five long-term experiments (run...

Geotourism is a sustainable type of tourism that focuses on the geological and geomorphological heritages of an area, and the associated cultural and biodiversity features. Though the popularity of geotourism is rapidly growing, research on the demand side, particularly on segmenting tourists to geosites and understanding their profiles, is limited...

Soil water retention (SWR) is an important soil property related to soil structure, texture, and organic matter (SOM), among other properties. Agricultural management practices affect some of these properties in an interdependent way. In this study, the impact of management-induced changes of soil organic carbon (SOC) on SWR is evaluated in five lo...

This study assesses global landslide susceptibility (LSS) at the coarse 36-km spatial resolution of global satellite soil moisture observations, to prepare for a subsequent combination of a global LSS map with dynamic soil moisture estimates for landslide modelling. Global LSS estimation intrinsically contains uncertainty, arising from errors in th...

Intense gully erosion has sculptured remarkable channels into the Moldavian Plateau of eastern Romania, especially in its most representative subunit, the Bârlad Plateau covering >8000 km². The permanent gully types are: (1) discontinuous gullies, mostly located on hillslopes and (2) large continuous gullies in valley bottoms. This study seeks to i...

Land degradation due to soil erosion presents a major challenge for sustainable development. We investigated runoff and sediment yield dynamics in the NW highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 m² to 1715 m². V-notch weirs produced from plastic jars were introduced as measuring al...

This study focuses on the Kuibyshev reservoir (Volga River basin, Russia)—the largest in Eurasia and the third in the world by area (6150 km2). The objective of this paper is to quantitatively assess the dynamics of reservoir bank landslides and shoreline abrasion at active zones based on the integrated use of modern instrumental methods (i.e., ter...

Significant developments in soil erosion research for the period 1950-2000 are reviewed. The main emphasis is on work in Western Europe and North America. We highlight work on process studies in splash, rill and gully erosion. Important developments also occurred in monitoring, measuring, and modelling erosion as well as recording and understanding...

Changes in future soil erosion rates are driven by climatic conditions, land use patterns, socio-economic development, farmers’ choices, and importantly modified by agro-environmental policies. This study simulates the impact of expected climatic and land use change projections on future rates of soil erosion by water (sheet and rill processes) in...

The European Commission's Thematic Strategy for Soil Protection (COM(2012)46) identified soil erosion as an important threat to European Union's (EU) soil resources. Gully erosion is an important but hitherto poorly understood component of this threat. Here we present the results of an unprecedented attempt to monitor the occurrence of gully erosio...

Rural–urban migration in developing countries is considered to be a key process for sustainable development in the coming decades. On the one hand, rural–urban migration can contribute to the socioeconomic development of a country. On the other hand, it also leads to labor transfer, brain-drain in rural areas, and overcrowded cities where planning...

Sunken lanes are roads or tracks, 2 m or more wide, that are incised at least 0.5 m, but often by several meters, below the general level of the surrounding land surface. They are formed by the passage of people, animals, vehicles and erosion by water and gravity. Although these anthropogenic landforms are quite common worldwide they received limit...

The study object is the Kuibyshev reservoir. The objective is to quantitatively assess reservoir bank landslides and shoreline abrasion in active zones based on the integrated use of modern instrumental methods. Different approaches are used to assess the intensity of landslide and abrasion processes: the specific volume and material loss index, th...

Soil erosion is an important problem in the loess landscapes of Europe, resulting in a lowering of soil quality and landscape changes. As a result of soil erosion, SOC is redistributed and stored in SOC pools within the landscape. Understanding the SOC dynamics is important because changes in the SOC stocks may have large impacts on global climate...

Gully erosion is a major environmental threat on the Moldavian Plateau (MP) of eastern Romania. The permanent gully systems consist of two main gully types. These are: (1) discontinuous gullies, which are mostly located on hillslopes and (2) large continuous gullies in valley bottoms. Very few studies have investigated the evolution of continuous g...

Sub-Saharan Africa is rapidly urbanising. This urbanisation may contribute to socio-economic development as more people participate in the urban economy. Nevertheless, rapid urbanisation is not always sustainable. Primary cities often grow fast, leaving secondary towns lagging behind with weaker economies. Viable strategies for sustainable urbanisa...

Study Region We investigate the event runoff response in six sub-catchments in the Lake Tana sub-basin, headwater of the Blue Nile basin, northwest Ethiopia. Steep and mountainous terrains surround floodplains, imposing runoff and soil erosion in the upper catchments and flooding and sedimentation at floodplains. This study was conducted in the upl...

Geotourism is a niche form of sustainable tourism that focuses on the geological and geomorphological features of an area, and the associated culture and biodiversity. Geosites are important resources for geotourism development. The eastern and southeastern Lake Tana region in Ethiopia has several geosites with a potential for geotourism developmen...

Lake Abaya and Lake Chamo are located within the rift valley that cuts across eastern Ethiopia. Severe soil erosion, predominantly gully erosion in the midlands and highlands, and flash flooding along rivers in the lowlands resulted in sediment and nutrient accumulation in the rift lakes. In this study, conducted in four river catchments on the Wes...

Questionnaire S1. Questionnaire for rating the scenic beauty of the 34 geosites by the NGB-NV and GB-NV groups 1 , based on representative photographs of the geosites. The objective of this questionnaire is to rate the scenic beauty of geosites. Geosites are understood here as geomorphological or geological features with associated cultural and/or...

Scenic beauty is one of the most-commonly used indicators in the inventory and assessment of geosites for geoconservation, geoheritage management and geotourism development. It is an important driver of tourists to visit natural areas and it also provides support for the protection of natural heritage. Previous studies on scenic beauty mainly focus...

Land degradation due to soil erosion presents a challenge for sustainable development. We investigated the impact of land use type and land management practices on runoff and sediment yield dynamics in the northwestern highlands of Ethiopia. The study area included 14 zero-order catchments with a surface area ranging from 324 m2 to 1715 m2. V-notch...

Soil erosion is generally recognized as the dominant process of land degradation. The formation and expansion of gullies is often a highly significant process of soil erosion. However, our ability to assess and simulate gully erosion and its impacts remains very limited. This is especially so at regional to continental scales. As a result, gullying...

This global feasibility study assesses the potential of coarse-scale, gridded soil water estimates for the probabilistic modeling of hydrologically-triggered landslides, using Soil Moisture Ocean Salinity (SMOS), Soil Moisture Active Passive (SMAP) and Gravity Recovery and Climate Experiment (GRACE) remote sensing data, Catchment Land Surface Model...

Gully erosion is a major environmental problem, posing significant threats to sustainable development. However, insights on techniques to prevent and control gullying is scattered and incomplete, especially regarding failure rates and effectiveness. This review aims at addressing these issues and contribute to more successful gully prevention and c...

Permanent gullies and badlands are found on all continents and their spectacular nature and beauty has attracted scientists, artists and tourists. These landforms are elements of geomorphic heritage and development of geoeducation is the best way to transfer geomorphological knowledge to society. Gullies and badlands have been studied for many year...

Lake sediment budgeting is a vital tool to better understand catchment sediment fluxes. It allows assessing lake lifetimeand can be used to design improved catchment management plans. Over the past fewyears,we collected sediment and runoff discharge data at fine spatial-temporal resolutions for the Lake Tana Basin (LTB), Ethiopia. Based on these da...

Sunken lanes or ‘road gullies’ are a common geomorphic feature in the European loess belt. These landforms are usually created by various processes over time (water erosion, mass movements and traffic). They are important for ecology and biodiversity, for recreation and transport, as well as from a hydrological and geomorphological perspective (e.g...

Despite its environmental and scientific significance, predicting gully erosion remains problematic. This is especially so in strongly contrasting and degraded regions such as the Horn of Africa. Machine learning algorithms such as random forests (RF) offer great potential to deal with the complex, often non‐linear, nature of factors controlling gu...

Concentrated flow erosion poses a serious threat to agriculture across the world as it scours soils into linear features that can be wide and large, which dramatically decreases land productivity and accessibility, and causes serious downslope and downstream impacts. Despite the widespread occurrence of concentrated flow erosion features across the...

Gully erosion is a major driver of elevated sediment yields across many areas of the globe, and considerable rehabilitation has occurred to reduce the amount of sediment eroded from gullies. However, compared to other forms of erosion, there has been little systematic review of the effectiveness of gully rehabilitation on reducing sediment yields....

The objective of the study on which the article is based was to investigate the distribution, characteristics and livelihood effects of debris cones in the Aba'ala and Raya grabens in Ethiopia. The characteristics of the debris cones and their upper catchment areas were obtained from Google Earth Pro and Landsat images. Questionnaires were used to...

Soil erosion is one of the eight threats in the Soil Thematic Strategy, the main policy instrument dedicated to soil protection in the European Union (EU). During the last decade, soil erosion indicators have been included in monitoring the performance of the Common Agricultural Policy (CAP) and the progress towards the Sustainable Development Goal...

Land degradation by water and wind erosion is a serious problem worldwide. Despite the significant amount of research on this topic, quantifying these processes at large- or regional-scale remains difficult. Furthermore, very few studies provide integrated assessments of land susceptibility to both water and wind erosion. Therefore, this study inve...

Landslides are a main driver of landscape evolution and a dominant sediment source in many regions worldwide. Nevertheless, their role in sediment mobilization and denudation remains poorly quantified, especially at the global scale. Based on an extensive literature review, we compiled measured contemporary landslide mobilization rates (i.e. the av...

Knowledge of the geographical distribution of soils is indispensable for policy and decision makers to achieve the goal of increasing agricultural production and reduce poverty, particularly in the Global South. A study was conducted to better understand the soilscapes of the Giba catchment (900–3300 m a.s.l.; 5133 km²) in northern Ethiopia, so as...

Gully erosion is a process whereby runoff water concentrates over short periods and removes the soil, sometimes to considerable depths (Poesen et al., 2003). Landslides include a range of processes by which slope material is displaced under the force of gravity (Hungr et al., 2014). Gullies and landslides play an essential role in landscape evoluti...

Focus: matching agricultural water demand and supply is a growing policy challenge in drylands. We investigated the water balance components in Raya (3507 km 2) and Ashenge (80.5 km 2) grabens. The rainfall depth, river discharge, abstraction, climate and soil data (2015-2017) were used to address the research question. New hydrological insights: t...

Little is known about the contribution of bedload flux to the total sediment load exported from tropical sand-bed rivers. Yet, predicting bedload transport rates contributes to better river management, more appropriate river engineering works design, accurate knowledge of sediment delivery rates, which greatly benefits sediment related water resour...

We aim to assess the spatial patterns of water and wind erosion risks over the drought-prone Eastern Africa region. A spatially distributed Revised Universal Soil Loss Equation was adopted for water erosion assessment and validated against observed sediment yield data from 100 watersheds (r2 = 0.4). A wind erosion index was developed by integration...

Extensive catchment degradation throughout the Ethiopian highlands induced by long‐term intensified land use, erosion prone topography and climate cause substantial soil erosion that limits agricultural productivity and result lake sedimentation. However, before taking soil conservation measures, management of the soil loss problem essentially need...

As a response to low agricultural productivity, inorganic fertiliser sales have exponentially grown in Ethiopia, and evidence exists of a supply that is beyond the demand in the drier northern parts of the country. Hence, we have investigated the geographical determinants of the fertiliser black market in north Ethiopia. Quantitative data on fertil...

The natural heritage of any country includes its geological heritage, made up of many key geosites, as well as landscapes, profoundly shaped and defined by their geology. Rocks, minerals, fossils, geomorphological and geological features are just as much natural heritage as living plants and animals and all of these define the geodiversity of a reg...

Late-Pleistocene and Holocene environmental changes in Dogu’a Tembien are evidenced by cyclic alternation of stable and active morphogenetic periods. Stable phases correspond to periods of longitudinal river profile stabilisation through the development of river tufa dams (see Chapter 8), by (1) development of forest vegetation, protecting soil aga...

A highly seasonal and erratic rainfall pattern (Chapter 3) seems to provoke general water scarcity in Dogu’a Tembien for eight months a year. This chapter shortly describes the hydrogeological context and hydrodynamics of actual surface and groundwater flow of the mountain catchments around Hagere Selam. Further, some positive effects of water harv...

Soil erosion is the detachment and transport of soil particles by a transporting agent, predominantly water flowing over the soil surface (runoff). In Dogu’a Tembien, millennia of plough-based agriculture, steep topography, population pressure and poverty have contributed to accelerated soil erosion processes. On agricultural fields (ca. 65% of the...

The Giba, Tanqwa and Tsaliet rivers in the headwaters of the Tekezze basin are the most important rivers in Dogu’a Tembien and its surroundings. The rivers and their tributaries have cut deep gorges and shaped the landscape. Whereas Ethiopia is well endowed with potential water resources, which are estimated to be around 110 billion m³ per year, th...

Mass movements comprise the sliding, tumbling or falling of rock fragments and fine earth masses, largely under the force of gravity. Mass movement bodies are conspicuous on escarpments and on foot slopes of the tabular ridges of Dogu’a Tembien. Two main types can be distinguished: (1) rockfall resulting in scree slopes and (2) landslides, mostly d...

Sediment yield (SY) is the total mass of sediment that leaves a catchment per unit of time. It is the combined result of several erosion processes (e.g. sheet and rill erosion, gully erosion, riverbank erosion, landslides) and sediment deposition (e.g. at field boundaries, on footslopes, alluvial plains, river beds) taking place in the river catchm...

Given the mountainous character of Dogu’a Tembien along with a strong variability in lithology, topography and climate, a wide range of soil types can be expected. Nevertheless, the occurrence of soil types and sequences (catenas) is all but random. The nature of the soil can be predicted from its setting in the overall landscape. In this paper, th...

In Dogu’a Tembien croplands occur on most level lands, but one may wonder about the sustainability of cropping and grazing on steep slopes. Obviously, in the framework of extensive agriculture, increasing population density has gradually led to land use beyond its capacity. As land is not plenty and infinite, it needs to be appropriately used in or...