Gerard Govers

• PhD
• Professor (Full) at KU Leuven

Over the past years, microbially driven models have been developed to improve simulations of soil organic carbon (SOC) and have been put forward as an improvement to assess the fate of SOC stocks under environmental change. While these models include a better mechanistic representation of SOC cycling compared to cascading-reservoir-based approaches...

The catchment of Lake Alaotra, a large shallow lake (surface is 200 km2, maximum depth 2 m) in the Malagasy highlands, is a region where the grassland dominated landscape is dotted by major gullies called “lavaka”, which has historically been claimed to lead to high erosion rates. Sedimentary archives in lakes such as Lake Alaotra could be of great...

Over the past years, microbially-driven models have been developed to improve simulations of soil organic carbon (SOC), and have been put forward as an improvement to assess of the fate of SOC stocks under environmental change. While these models do include a better mechanistic representation of SOC cycling in comparison to cascading reservoir-base...

Predicting the quantity of soil organic carbon (SOC) requires understanding how different factors control the amount of SOC. Land use has a major influence on the function of the soil as a carbon sink, as shown by substantial organic carbon (OC) losses from the soil upon deforestation. However, predicting the degree to which land use change affects...

The rapid urbanization in Africa profoundly affects local food and ecological systems. According to earlier research, urbanization may cause food production and biodiversity losses as agricultural or natural lands are absorbed by expanding cities. Land-use displacement effects may buffer agricultural production losses or may lead to additional biod...

Predicting the quantity of soil organic carbon (SOC) requires understanding about how different factors control the amount of SOC. Land use has a major influence on the function of the soil as a carbon sink, as shown by substantial organic carbon (OC) losses from the soil upon deforestation. Yet, predicting the degree to which land use change affec...

The rapid urbanization in Africa profoundly affects local food and ecological systems. According to earlier research, urbanization may cause food production and biodiversity losses as agricultural or natural lands are absorbed by expanding cities. Although land use displacement effects may potentially buffer agricultural production losses or lead t...

As Africa is facing multiple challenges related to food security, frameworks integrating production and availability are urgent for policymaking. Attention should be given not only to gradual socio-economic and climatic changes but also to their temporal variability. Here we present an integrated framework that allows one to assess the impacts of s...

Cosmogenic nuclide analysis of river sediment provides insight into catchment wide erosion rates and dynamics. Here, we investigate spatial patterns and controls on 10Be-inferred erosion rates in Madagascar, a moderately seismically active microcontinent surrounded by passive margins with locally steep topography and a climate that varies from humi...

Given the projected population growth and rice consumption in Madagascar, assessing its rice production potential is important. Existing spatial representations of rice are characterized by coarse resolutions and diverge widely. Mapping rice production based on remote sensing offers a potential solution to this problem but its application in Sub-Sa...

Erosion exerts control on soil organic carbon (SOC) and both erosion and SOC are affected by climate. To what extent temperature controls the coupling between these erosion–C interactions remains unclear. Using ¹³⁷Cs and SOC inventories from catchments spanning different climates, we find that increasing decomposition rates with temperature result...

Tidal marshes and mangroves are threatened by relative sea level rise (RSLR) in certain regions on Earth. Elsewhere, these coastal wetlands can adapt through sediment accretion and resulting surface elevation gain. Studies identifying drivers of the global variability in coastal wetland adaptability to RSLR ignored the role of the tidal pattern, va...

Food security and nutrition security raise multiple questions at both the local and global levels. Experts have formulated three major challenges for the 21st century in this regard: the depletion of natural materials, the loss of environmental quality, and the assurance or guarantee of food supplies. Will we be able to produce enough food for an e...

Madagascar is known for its high erosion rates in the central highlands, yet the role of human disturbance versus natural processes is not well understood and is a topic of ongoing debate. At present the necessary quantitative data to couple vegetation dynamics and sediment fluxes over time in Madagascar is scarce. This study aims to provide more i...

Past experimental work found that rill erosion occurs mainly during rill formation in response to feedback between rill-flow hydraulics and rill-bed roughness, and that this feedback mechanism shapes rill beds into a succession of step-pool units that self-regulates sediment transport capacity of established rills. The search for clear regularities...

The extent to which the central highlands of Madagascar were once covered by forests is still a matter of debate: while reconstructing past environments is inherently difficult, the debate is further hampered by the fact that the evidence documenting land cover changes and their effects on carbon and sediment dynamics in Madagascar has hitherto mai...

Mangroves are widely recognised as key ecosystems for climate change mitigation as they capture and store significant amounts of sediment organic carbon (SOC). Yet, there is incomplete knowledge on how sources of SOC and their differential preservation vary between mangrove sites in relation to environmental gradients. To address this, sediment dep...

Over the past few decades, developments in remote sensing have resulted in an ever-growing availability of topographic information on a global scale. A recent development is TanDEM-X (TerraSAR-X add-on for digital elevation measurements), an interferometric synthetic aperture radar (SAR) mission of the Deutsche Zentrum für Luft- und Raumfahrt, prov...

Although estuaries are considered important pathways in the global carbon cycle, carbon dynamics in tropical estuaries is relatively understudied. Here, the tidal, seasonal and spatial variability of particulate organic carbon (POC), dissolved inorganic carbon (DIC), carbon dioxide (CO2) and methane (CH4), among other biogeochemical variables relat...

The extent to which the central highlands of Madagascar were once covered by forests is still a matter of debate: while reconstructing past environments is inherently difficult, the debate is further hampered by the fact that the evidence documenting land cover changes and their effects on carbon and sediment dynamics in Madagascar has hitherto mai...

Ons voedselsysteem, en meer in het bijzonder de manier waarop we aan landbouw doen, legt momenteel een onhoudbare druk op milieukwaliteit, biodiversiteit en klimaat. In deze bijdrage formuleren de auteurs eerst een reeks bedenkingen bij een eerder in Natuurfocus verschenen artikel waarin als oplossing voor dit probleem de agro-ecologische landbouw...

Land use and land cover changes (LUCC) can drastically alter various components of the critical zone, including soil thickness and soil chemical weathering processes. Often these studies, however, tend to focus on extreme cases, not representing what actually happens on average at larger, regional scales. Here, we evaluate the impact of LUCC on soi...

Human activity influences both the occurrence and impact of landslides in mountainous environments. Population pressure and the associated land-use changes are assumed to exacerbate landslide risk, yet there is a lack of statistical evidence to support this claim, especially in the Global South where historical records are scarce. In this work, we...

Lavaka (gullies) are often considered as the prime indication of a currently ongoing human-induced environmental crisis in Madagascar's highlands. Yet, lavaka are known to have existed long before human arrival and account for the majority of the long-term sediment input into the highland rivers and floodplains. The role of anthropogenic disturbanc...

Over the past decades, developments in remote sensing have resulted in an ever growing availability of topographic information on a global scale. A recent development is TanDEM-X, an interferometric SAR mission of the Deutsche Zentrum für Luft- und Raumfahrt providing near-global coverage and high resolution DEMs. Moreover, ongoing developments in...

We compiled an extensive database of erosion and runoff measurements on erosion plots under natural rainfall in China. We used this database to analyse how soil loss by sheet and rill erosion and runoff in China were affected by land use, slope gradient, slope length and mean annual precipitation. Our results show that land use dominates the variat...

Mangroves are widely recognised as key ecosystems for climate change mitigation as they capture and store significant amounts of sediment organic carbon (SOC). Yet, there is incomplete knowledge on how sources of SOC and their differential preservation vary between mangrove sites in relation to environmental gradients. To address this, sediment dep...

As greenhouse warming is predicted to intensify the El Niño–Southern Oscillation (ENSO), it is key to understand relationships between the magnitudes and spatial distribution of ENSO events and associated extreme sea levels (ESLs). Current understanding is lacking for river deltas, where human societies and ecosystems are particularly vulnerable to...

Deforestation is associated with a decrease in slope stability through the alteration of hydrological and geotechnical conditions. As such, deforestation increases landslide activity over short, decadal timescales. However, over longer timescales (0.1–10 Myr) the location and timing of landsliding is controlled by the interaction between uplift and...

Different erosion processes deliver large amounts of terrestrial soil organic carbon (SOC) to rivers. Mounting evidence indicates that a significant fraction of this SOC, which displays a wide range of ages, is rapidly decomposed after entering the river system. The mechanisms explaining this rapid decomposition of previously stable SOC still remai...

Deforestation increases landslide activity over short, contemporary timescales. However, over longer timescales, the location and timing of landsliding is controlled by the interaction between uplift and fluvial incision. Yet, the interaction between (human-induced) deforestation and landscape evolution has hitherto not been explicitly considered....

Human-induced soil erosion is a serious threat to global sustainability, endangering global food security, driving desertification and biodiversity loss, and degrading other vital ecosystem services. To help assess this threat, we amassed a global inventory of soil erosion rates consisting of 10,030 plot years of data from 255 sites under conventio...

Rivers receive large amounts of terrestrial soil organic carbon (SOC) due to the action of different erosion processes. Mounting evidence indicates that a significant fraction of this SOC, which is often very old, is rapidly decomposed after entering the river system. The mechanisms explaining this rapid decomposition of previously stable SOC still...

Landscape evolution models can be used to assess the impact of rainfall variability on bedrock river incision over millennial timescales. However, isolating the role of rainfall variability remains difficult in natural environments, in part because environmental controls on river incision such as lithological heterogeneity are poorly constrained. I...

Soil thickness and residence time are regulated by a dynamic interplay between soil formation and lateral transport of soil particles and solutes. To unravel this interplay and infer patterns and rates of chemical weathering, soil physical and chemical properties can be used. Here, we present an integrated approach combining numerical modeling with...

In the 1990s, some districts in the Northern Vietnamese highlands were opened for international tourism. The development of tourism was expected to bring a new income source to remote mountain areas. This paper analyzes the association between tourism development, local livelihoods and land cover change at the household level. Sa Pa district was se...

Numerous fixed or movable flume experiments have been conducted to characterize the hydraulic resistance of concentrated flow on natural and tilled surfaces. However, few studies have elucidated how the friction factor of flow resistance evolves over time on tilled surfaces. Since hydraulic resistance and concentrated flow interact with each other,...

Predicting landslide occurrence is of key importance for understanding the geomorphological development of mountain environments as well as to assess the potential risk posed by landsliding to human societies in such environments. Global landslide susceptibility models use a generic model formulation to predict landslide susceptibility anywhere on...

Process-based geomorphic transport laws enable to assess the impact of rainfall variability on bedrock river incision over geological timescales. However, isolating the role of rainfall variability on erosion remains difficult in natural environments in part because the variability of rock strength and its resistance to incision are poorly constrai...

Rills are generated on homogeneous hillslopes by the action of different discharges and evolve morphologically over short timescales due to a strong interaction between the flow and bed morphology. Such an interaction generates a reconfiguration of the bed geometry. Previous works suggest that bed geometry is often characterized by alternation betw...

Review studies indicate that conservation tillage effectively reduces runoff generation measured on large plots, but less so on smaller plots. These tillage and scale effects have never been measured in a single study for temperate mechanized agriculture. With the objective to study how runoff production changes with scale as influenced by tillage...

The efficacy of soil and water conservation measures (SWCMs) on reducing the loss of soil and water has been widely tested at the plot scale in China. However, an integrated comparison of the efficacy and an overall investigation of the controlling factors of the efficacy is absent. Therefore, an extensive dataset compiling erosion plot measurement...

Tidal marshes are coastal and estuarine ecosystems that store large amounts of sedimentary organic carbon (OC). Despite the valuable ecosystem services they deliver, tidal marshes have been converted to other land use types over the past centuries. Although previous studies have reported large decreases in soil organic carbon (SOC) stocks after tid...

Tidal marshes are coastal ecosystems that store large amounts of sedimentary organic carbon (OC). Reducing the current uncertainty on the amount of OC stored these sediments requires the analysis of a large number of sediment samples. Soil sensing techniques, using mid infrared (MIR) spectroscopy combined with partial least squares regression (PLSR...

The impact of forest conversion on soil weathering is studied in a subtropical humid setting in southern Brazil (Rio Grande do Sul). A geochemical tracer of mineral weathering processes, the Ge/Si ratio, was used at the pedon and catchment scales to compare a cropland and a forest catchment. Ge/Si measurements were performed on bedrock, bulk soil,...

Gully erosion is an important process of land degradation in mountainous regions, and is known to be one of the major sediment sources in eroded catchments. Recent studies have suggested that living and dead vegetation can be effective for ecosystem restoration, and large-scale restoration projects have been implemented in the tropical Andes in rec...

The North Tanganyika and Kivu Rift zones (Burundi, DR Congo, Rwanda) encompass a region where environmental factors such as heavy rainfall, tectonic activity, and steep topography favor the occurrence of landslides. These landslides have a negative impact on the livelihoods of the local population that suffers yearly from damage to infrastructure a...

The North Tanganyika and Kivu Rift zones (Burundi, DR Congo, Rwanda) encompass a region where environmental factors such as heavy rainfall, tectonic activity, and steep topography favor the occurrence of landslides. These landslides have a negative impact on the livelihoods of the local population that suffers yearly from damage to infrastructure a...

The hydrological status of river systems is expected to change due to dam operations and climate change. This will affect the riverine fluxes of sediment and carbon (C). In rivers with strong seasonal and inter-annual variability, quantification and extrapolation of sediment and C fluxes can be a challenge as measurement periods are often too short...

Quick, reliable and accurate estimates of soil water content (SWC) at intermediate (slope) to larger scale (catchment) are important for understanding hydrological processes and may be provided by electromagnetic induction (EMI). EMI measures the apparent electrical conductivity of the subsurface (ECapp) which represents a depth weighted average va...

Tidal marshes are vegetated coastal ecosystems that are often considered as hotspots of atmospheric CO2 sequestration. Although large amounts of organic carbon (OC) are indeed being deposited on tidal marshes, there is no direct link between high OC deposition rates and high OC sequestration rates due to two main reasons. First, the deposited OC ma...

Mountains play an important role in the denudation of continents and transfer erosion and weathering products to lowlands and oceans. The rates at which erosion and weathering processes take place in mountain regions have a substantial impact on the morphology and biogeochemistry of downstream reaches and lowlands. The controlling factors of physic...

Core Ideas This special section is a snapshot of current work and understanding of lateral surface transport processes. The particular focus is on soil erosion. Soil erosion is a very large and very important topic. It must be addressed from both practical and rigorous scientific angles. Erosion can cause serious agricultural and environmental haz...

Land use/cover change (LUCC), and more specifically deforestation and multi‐decadal agriculture, is one of the various controlling factors of water fluxes at the hillslope or catchment scale. We investigated the impact of LUCC on water pathways and stream stormflow generation processes in a subtropical region in southern Brazil. We monitored, sampl...

Erosion of agricultural land is estimated to have resulted in a cumulative net uptake of 78 [plusmn] 22[thinsp]Pg[thinsp]C on land (6000 BC-2015 AD), offsetting 37 [plusmn] 10% of generally recognized C emissions resulting from anthropogenic land cover change.

Soil erosion severely threatens the soil resource and the sustainability of agriculture. After decades of research, this problem still persists, despite the fact that adequate technical solutions now exist for most situations. This begs the question as to why soil conservation is not more rapidly and more generally implemented. Studies show that th...

Quantification of sediment and carbon (C) fluxes in rivers with strong seasonal and inter-annual variability presents a challenge for global flux estimates as measurement periods are often too short to cover all hydrological conditions. We studied the dynamics of the Tana River (Kenya) from 2012 to 2014 through daily monitoring of sediment concentr...

Purpose This study illustrates the applicability of a framework to conduct a spatially distributed inventory of suspended solids (SS) delivery to freshwater streams combined with a method to derive site-specific characterisation factors for endpoint damage on aquatic ecosystem diversity. A case study on Eucalyptus globulus stands located in Portuga...

Landscape evolution models (LEMs) allow the study of earth surface responses to changing climatic and tectonic forcings. While much effort has been devoted to the development of LEMs that simulate a wide range of processes, the numerical accuracy of these models has received less attention. Most LEMs use first-order accurate numerical methods that...

Rivers transport sediment and carbon (C) from the continents to the ocean, whereby the magnitude and timing of these fluxes depend on the hydrological regime. We studied the sediment and carbon dynamics of a tropical river system at two sites along the lower Tana River (Kenya), separated by a 385 km stretch characterized by extensive floodplains, t...

Tidal marshes are sedimentary environments and are among the most productive ecosystems on Earth. As a consequence they have the potential to reduce atmospheric greenhouse gas concentrations by sequestering organic carbon (OC). In the past decades, most research on soil organic carbon (SOC) storage in marsh environments has focused on salt marshes,...

This is the supplementary information that supports Van de Broek et al. 2016, Controls on soil organic carbon stocks in tidal marshes along and estuarine salinity gradient, Biogeosciences

Despite a multitude of studies, overall erosion rates as well as the contribution of different erosion processes on Chinese Loess Plateau (CLP) remain uncertain, which hampers a correct assessment of the impact of soil erosion on carbon and nutrient cycling as well as on crop productivity. In this paper we used a novel approach, based on field evid...

Tidal marshes are sedimentary environments that are among the most productive ecosystems on earth. As a consequence tidal marshes, and vegetated coastal ecosystems in general, have the potential to reduce atmospheric greenhouse gas concentrations as they efficiently sequester soil organic carbon (SOC). In the past decades, most research has focused...

While the implementation of soil conservation depends on a multitude of factors, it is also clear that rapid change in agricultural systems only happens when a clear economic incentive is present. This fact, as well as the fact that agriculture will change fundamentally in the Global South over the next decades, need to be accounted for when develo...

Landscape evolution models (LEM) allow studying the earth surface response to a changing climatic and tectonic forcing. While much effort has been devoted to the development of LEMs that simulate a wide range of processes, the numerical accuracy of these models has received much less attention. Most LEMs use first order accurate numerical methods t...

The remarkable complexity of soil and its importance to a wide range of ecosystem services presents 133 major challenges to the modeling of soil processes. Although major progress in soil models has 134 occurred in the last decades, models of soil processes remain disjointed between disciplines or 135 ecosystem services, with considerable uncertain...

Core Ideas A community effort is needed to move soil modeling forward. Establishing an international soil modeling consortium is key in this respect. There is a need to better integrate existing knowledge in soil models. Integration of data and models is a key challenge in soil modeling. The remarkable complexity of soil and its importance to a wi...

We reviewed soil modeling and the role of soil processes in quantifying ecosystem services. Key challenges were identified and the establishment of a soil modeling consortium to advance soil modeling activities, provide a data-model platform, perform model intercomparison and foster communication amongst Earth science disciplines is proposed.

Floodplains exert strong controls on downstream sediment transport and are as such important in material budgets of river systems. To understand sediment budgets in the Tana River, we investigated sediment storage along a 380 km floodplain reach (Garissa-Garsen) in the lower Tana River (Kenya), using a combination of approaches: (i) measurements of...

Inland waters organic carbon (OC) burial by sedimentation has recently been shown to be an important component in river catchment carbon (C) budgets. However, data on OC burial by sedimentation are hitherto largely limited to temperate zones. We investigated the deposition and fate of sediment-associated OC in the floodplains of the tropical lowlan...

Meteoric 10Be allows for the quantification of vertical and lateral soil fluxes over long time scales (103-105 yr). However, the mobility of meteoric 10Be in the soil system makes a translation of meteoric 10Be inventories into erosion and deposition rates complex. Here, we present a spatially explicit 2D model simulating the behaviour of meteoric...

A significant amount of carbon is transported to the ocean as dissolved organic carbon (DOC) in rivers. During transport, it can be transformed through microbial consumption and photochemical oxidation. In dark incubation experiments with water from the Tana River, Kenya, we examined the consumption of DOC through microbial decomposition and the as...

p>The remarkable complexity of soil and its importance to a wide range of ecosystem services presents major challenges to the modeling of soil processes. Although major progress in soil models has occurred in the last decades, models of soil processes remain disjointed between disciplines or ecosystem services, with considerable uncertainty remaini...

Despite a multitude of studies, erosion rates as well as the contribution of different processes on Chinese Loess Plateau (CLP) remain uncertain. This makes it impossible to correctly assess the impact of conservation programs and the magnitude of the erosion-induced carbon sink. We used a novel approach, based on field evidence, to reassess erosio...

Besides well-known effects of climate and parent material on silicate weathering the role of land use change as a driver in the global silicon cycle is not well known. Changes in vegetation cover have altered reservoirs of silicon and carbon in plants and soils. This has potential consequences for plant-Si availability, agricultural yields, and coa...