V. Souchere - Profile on Academia.edu (original) (raw)
Papers by V. Souchere
Estimation of erosion and sediment export from an agricultural catchment (1960-2000) confronting the outputs of an expert-based model and Cs-137 inventories
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to quantify erosion and to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of
Agriculture, Ecosystems & Environment, 2010
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of the different land use conditions were simulated using the STREAM expert-based erosion model. A 13 years long sequence of rainfall events was run with this model. Results showed that erosion increased dramatically after land consolidation (+168% on average). Interannual variability of erosion is important. After land consolidation, 79% of erosion was observed in summer and autumn, even though these seasons only accounted for 58% of annual rainfall kinetic energy. The bulk of erosion was hence produced by a few intense thunderstorms during this period. Thunderstorms correspond to 5% of rainfall events and to 15% of the total rainfall depth, but they generate 51% of total annual erosion after land consolidation (and up to 57% of erosion before land consolidation). Confrontation of the STREAM model outputs with the erosion rates modelled based on Cs-137 measurements suggested that soil redistribution within the catchment was very high but that sediment exports from the catchment remained limited (sediment delivery ratio between 1% and 10%). Local erosion rates derived from Cs-137 measurements showed an important and organised spatial variability, but erosion rates integrated over larger areas remained in the same order of magnitude as those simulated by the STREAM model or were slightly higher. Water erosion would hence not be the only process generating erosion within this catchment. In this context, our results show that tillage erosion cannot be neglected to calculate the sediment budget over several decades.
La posture du commodiens: un savoir être, des savoir-faire
Linking cropping system mosaics to disease resistance durability
Ecological Modelling, 2015
ABSTRACT Cultivar resistance plays a major role in current disease management strategies, but its... more ABSTRACT Cultivar resistance plays a major role in current disease management strategies, but its efficacy is usually short-lived unless resistance deployment strategies to ensure resistance durability can be designed. Using a spatially explicit model, we evaluated cropping system mosaics that were designed by stakeholders involved in field agronomic practices to manage phoma stem canker of winter oilseed rape. We simulated pathogen population adaptation to a newly introduced major resistance gene (RlmX) to estimate the durability of the resistance under various scenarios of cropping system mosaics within a small region. Our objective was first to find descriptors of agricultural landscape that are relevant for resistance management and then to study the relationship between cropping practices applied in nearby fields and the genetic structure of the pathogen population in fields cropped with RlmX-cultivars. Key cropping practices were characterized with different metrics for several buffer sizes (100–2000 m) around target fields; and these indicators were used in linear models to predict pathogen evolution. Indicators describing local cultivar composition were very informative; adding information on tillage, but not nitrogen fertilization or fungicide treatment, could marginally increase the goodness of fit. The effects of cropping practices on resistance durability could be shown when the landscape was characterized within 500 m around RlmX-fields. We conclude that, in order to study and ultimately design landscapes promoting resistance durability against phoma stem canker, it is sufficient to take into account a relatively small portion of the landscape around RlmX-cultivars, focusing on cultivar choice and tillage practices of RlmX cultivated fields.
Boardman/Soil Erosion in Europe, 2006
Boardman/Soil Erosion in Europe, 2006
France has a large variety of landscapes, including high mountains in the east and south-west (Al... more France has a large variety of landscapes, including high mountains in the east and south-west (Alps, Pyrenees) and extensive plains and plateaux of the Aquitaine and the Paris basins open to the west, with altitudes mostly below 200 m. Ancient Hercynian massifs lie around their rims. Among them, the Vosges and the Massif Central were thrown outwards at the time of uplifting of the Alpine range. The Massif Central contains many volcanoes. Massifs of the Tertiary Period (Jura, Pre-Alps) are made up of folded sedimentary rock, mainly limestone. Main river valleys mark the eastern part with the Rhone valley that opens towards the Mediterranean and, in the north, the western part of the upper Rhine floodplain.
Spatial cultivar deployment and residue management : what impact for phoma stem canker of winter oilseed rape and resistance sustainability?
Meta-modelling of the impacts of regional cropping system scenarios for phoma stem canker control
European Journal of Agronomy, 2015
Estimation of erosion and sediment export from an agricultural catchment (1960-2000) confronting the outputs of an expert-based model and Cs-137 inventories
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to quantify erosion and to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of
Grass covers as tools for the reduction of soil losses by water erosion (a synthesis of knowledge and of information gained in Upper Normandy)
In loamy areas of Northern Europe, soil erosion is a widespread phenomenon, despite low rainfall ... more In loamy areas of Northern Europe, soil erosion is a widespread phenomenon, despite low rainfall intensity and a gentle topography. Interactions between meteorological conditions, farming operations and topsoil texture bring about rapid and significant changes in the hydraulic properties of topsoil.
Soil and Tillage Research, 2002
In the Normandy region of France, two extreme runoff events took place during winter of 1999 and ... more In the Normandy region of France, two extreme runoff events took place during winter of 1999 and spring of 2000 that caused ooding and considerable on-site as well as off-site damages. After each event, erosion damage was mapped on an experimental cultivated catchment (94 ha). The location and extent of rill, ephemeral gullies and deposits were measured. For each ®eld, information on land use and soil surface characteristics were also collected. Since 1991, when experimental work and survey campaigns were initiated on this catchment, interrill erosion dominated over rill or ephemeral gully erosion. Our objective was to link information on topography, soil surface characteristics, and land use with intensity and type of erosion that developed. Erosion features that were most related to topographic attributes and hence less affected by seasonal variations were ephemeral gullies and some prede®ned deposit types. Topographic attributes alone were not suf®cient to determine development of rill erosion, due to seasonal differences in vegetative cover. At the catchment scale, total erosion varied from 10 t/ha in December with 93% of the catchment area with vegetation cover 20%; to 1.5 t/ha in May, with 73% of the catchment area with vegetation cover >60%. The relative importance of ephemeral gully erosion out of total linear erosion varied from ca. 24% for the rainfall events of December to more than ca. 83% for the rainfall events of May. These results also highlight the fact that average annual sediment delivery as well as the relative importance of different erosion forms at the catchment scale cannot be generalised. Erosion prediction and erosion assessment risks are strongly dependent on catchment land use, morphology and storm characteristics. #
Effects of tillage on runoff directions: consequences on runoff contributing area within agricultural catchments
Journal of Hydrology, 1998
In areas of intensive agriculture, e.g. ‘Pays de Caux’ in France, which was the study area, field... more In areas of intensive agriculture, e.g. ‘Pays de Caux’ in France, which was the study area, field observations have shown that runoff directions were modified by agricultural activities. In order to account for factors responsible for modifications of the runoff direction (roughness, tillage direction and agricultural patterns, e.g. dead furrow or dirt tracks), we constructed a discriminant function based on field observations. This function enables us to decide whether flow direction for slopes of up to 15% was imposed by slope direction or tillage direction. It can be applied to any location, provided there are known roughness, known slope intensity, known aspect and known tillage azimuth.In order to examine the effects of these agricultural activities at the catchment scale, we compared two models by analysing the same hydrological variables: the area contributing to runoff and the flow network. The first model (Topo) was built according to the runoff direction derived from a Digital Elevation Model (DEM). The second model (Tillage) was constructed by combining information from the DEM, and information from rules based on field observations or resulting from statistical analysis.For 23 basic catchments, the result of the comparison between the two models (Topo and Tillage) showed that a major part of the catchments and the drainage network was affected by modifications related to the introduction of man-made agricultural factors. For example, for 20 of 23 catchments, the runoff flows over more than 50% of the surface of such areas were produced along the direction imposed by tillage. The introduction of tillage effect brings about modifications of both the shape and size of catchments.
Erosion and sediment budget across scale: A case study in a catchment of the European loess belt
Journal of Hydrology, 2012
... 2. Theoretical relationship between spatial scale and published mean sediment concentration d... more ... 2. Theoretical relationship between spatial scale and published mean sediment concentration derived from erosion rates in agricultural temperate areas of North-western Europe (over the loess belt), for arable lands with slopes between 2 and 5% ( (1) Fox and Bryan, 1999-(2 ...
International Journal of Sustainable Development, 2004
Runoff disregards territorial boundaries, affects farmers as well as other users of space, and ne... more Runoff disregards territorial boundaries, affects farmers as well as other users of space, and necessitates collective action if it is to be combatted. In this article, based on the case of Upper-Normandy, we show that geographical proximity can play a determining role in the struggle against erosive runoff, and we present a new tool for analysing relations of proximity between farmers. First we use three examples to show that farmers have only limited knowledge of the problem of erosion and are largely incapable of carrying out concerted collective action. That is why Syndicats de bassins versants were set up to provide organized proximity. Then we present a new tool for analysing relations of geographical proximity between farmed land and farmsteads, in order to assess the possibilities of coordination between farmers within catchment areas. Our results, based on the characterization of 1409 communes, clearly show that long distances, the size of farmed agricultural land and the high number of external farmers constitute major obstacles to the creation of ad hoc cooperative processes.
Earth Surface Processes and Landforms, 2002
A database composed of 673 natural rainfall events with sediment concentration measurements at th... more A database composed of 673 natural rainfall events with sediment concentration measurements at the field or plot scale was analysed. Measurements were conducted on similar soil type (loess soils prone to sealing phenomenon) to apprehend the variability and complexity involved in interrill erosion processes attributable to soil surface conditions. The effects of the dominant controlling factors are not described by means of equations; rather, we established a classification of potential sediment concentration domain according to combination of the dominant parameters. Thereby, significant differences and evolution trends of mean sediment concentration between the different parameter categories are identified. Further, when parameter influences interact, it allows us to discern the relative effects of factors according to their respective degree of expression. It was shown that crop cover had a major influence on mean sediment concentration, particularly when soil surface roughness is low and when maximum 6-min intensity of rainfall events exceeds 10 mm h 1 : mean sediment concentration decreases from 8Ð93 g l 1 for 0-20 per cent of coverage to 0Ð97 g l 1 for 21-60 per cent of coverage. The established classification also indicates that the increase of the maximum 6-min intensity of the rainfall factor leads to a linear increase of mean sediment concentration for crop cover over 21 per cent (e.g. from 2Ð96 g l 1 to 14Ð44 g l 1 for the 1-5 cm roughness class) and to an exponential increase for low crop cover (e.g. from 3Ð92 g l 1 to 58Ð76 g l 1 for the 1-5 cm roughness class). The implication of this work may bring perspective for erosion prediction modelling and give references for the development of interrill erosion equation.
CATENA, 2005
Over the last 30 years, European agricultural policy has influenced agricultural practices. These... more Over the last 30 years, European agricultural policy has influenced agricultural practices. These have led to an increase in numerous environmental issues such as the erosion and runoff risk, which have reached an alarming level in loamy soils of Upper Normandy. To control runoff and erosion at catchment scale, public authorities need tools in order to obtain a better knowledge of present or future pressure on the environment. With such information, it will be easier to act locally on a problem by avoiding negative impacts elsewhere in the area.
CATENA, 2005
Global climate has changed over the past century. Precipitation amounts and intensities are incre... more Global climate has changed over the past century. Precipitation amounts and intensities are increasing. In this study we investigated the response of seven soil erosion models to a few basic precipitation and vegetation related parameters using common data from one humid and one semiarid watershed. Perturbations were made to inputs for rainfall intensities and amounts, and to ground surface cover and canopy cover. Principal results were that: soil erosion is likely to be more affected than runoff by changes in rainfall and cover, though both are likely to be significantly impacted; percent erosion and runoff will likely change more for each percent change in rainfall intensity and amount than to each percent change in either canopy or ground cover; changes in rainfall amount associated with changes in storm rainfall intensity will likely have a greater impact on runoff and erosion than simply changes in rainfall amount alone; changes in ground cover have a much greater impact on both runoff and erosion than changes in canopy cover alone. The results do not imply that 0341-8162/$ -see front matter D .gov (M.A. Nearing).
CATENA, 2005
Extensive soil surface observations and measurements were conducted in Normandy on loess soils pr... more Extensive soil surface observations and measurements were conducted in Normandy on loess soils prone to surface crusting in order to understand the spatial distribution and temporal variability of soil surface characteristics involved in erosion processes. A database composed of more than 5000 soil surface observations at the field or plot scale was analysed. We classified these observations according to combinations of three dominant factors: crusting stage, roughness and crop cover. Frequency analysis showed that three combinations of these factors accounted for more than 50% of the total observations. Eight other combinations accounted each for more than 2% of the observations. These dominant and secondary combinations are considered as breference surface conditionsQ. Their potential range of the infiltration capacity and sediment production were estimated from field measurements under natural and simulated rainfall. For the loess soils in our study, mean field infiltration capacity ranged between 2 mm/h and 50 mm/h while mean sediment concentration ranged between 0.5 g/l and 30 g/l for the different combinations of soil surface and rainfall characteristics. This work, based on a local case study, allowed the development of a new approach for erosion prediction modelling (STREAM) which could be transferable to other areas where Hortonian processes are dominant. D
CATENA, 2003
This paper describes a new erosion model to predict the location and volume of ephemeral gullies ... more This paper describes a new erosion model to predict the location and volume of ephemeral gullies within the main runoff collector network of agricultural catchments. This model, using an expert-based approach, combines field experiment results and knowledge about erosion processes and agricultural practices. It takes into account slope gradient, parameters reducing runoff flow velocity or increasing soil resistance (land use, plant cover percentage, roughness and soil surface crusting stage), the hydrological structure of catchments and the runoff volume. The model is used to calculate the soil sensitivity to ephemeral gully erosion at any point in four small cultivated catchments.
Estimation of erosion and sediment export from an agricultural catchment (1960-2000) confronting the outputs of an expert-based model and Cs-137 inventories
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to quantify erosion and to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of
Agriculture, Ecosystems & Environment, 2010
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of the different land use conditions were simulated using the STREAM expert-based erosion model. A 13 years long sequence of rainfall events was run with this model. Results showed that erosion increased dramatically after land consolidation (+168% on average). Interannual variability of erosion is important. After land consolidation, 79% of erosion was observed in summer and autumn, even though these seasons only accounted for 58% of annual rainfall kinetic energy. The bulk of erosion was hence produced by a few intense thunderstorms during this period. Thunderstorms correspond to 5% of rainfall events and to 15% of the total rainfall depth, but they generate 51% of total annual erosion after land consolidation (and up to 57% of erosion before land consolidation). Confrontation of the STREAM model outputs with the erosion rates modelled based on Cs-137 measurements suggested that soil redistribution within the catchment was very high but that sediment exports from the catchment remained limited (sediment delivery ratio between 1% and 10%). Local erosion rates derived from Cs-137 measurements showed an important and organised spatial variability, but erosion rates integrated over larger areas remained in the same order of magnitude as those simulated by the STREAM model or were slightly higher. Water erosion would hence not be the only process generating erosion within this catchment. In this context, our results show that tillage erosion cannot be neglected to calculate the sediment budget over several decades.
La posture du commodiens: un savoir être, des savoir-faire
Linking cropping system mosaics to disease resistance durability
Ecological Modelling, 2015
ABSTRACT Cultivar resistance plays a major role in current disease management strategies, but its... more ABSTRACT Cultivar resistance plays a major role in current disease management strategies, but its efficacy is usually short-lived unless resistance deployment strategies to ensure resistance durability can be designed. Using a spatially explicit model, we evaluated cropping system mosaics that were designed by stakeholders involved in field agronomic practices to manage phoma stem canker of winter oilseed rape. We simulated pathogen population adaptation to a newly introduced major resistance gene (RlmX) to estimate the durability of the resistance under various scenarios of cropping system mosaics within a small region. Our objective was first to find descriptors of agricultural landscape that are relevant for resistance management and then to study the relationship between cropping practices applied in nearby fields and the genetic structure of the pathogen population in fields cropped with RlmX-cultivars. Key cropping practices were characterized with different metrics for several buffer sizes (100–2000 m) around target fields; and these indicators were used in linear models to predict pathogen evolution. Indicators describing local cultivar composition were very informative; adding information on tillage, but not nitrogen fertilization or fungicide treatment, could marginally increase the goodness of fit. The effects of cropping practices on resistance durability could be shown when the landscape was characterized within 500 m around RlmX-fields. We conclude that, in order to study and ultimately design landscapes promoting resistance durability against phoma stem canker, it is sufficient to take into account a relatively small portion of the landscape around RlmX-cultivars, focusing on cultivar choice and tillage practices of RlmX cultivated fields.
Boardman/Soil Erosion in Europe, 2006
Boardman/Soil Erosion in Europe, 2006
France has a large variety of landscapes, including high mountains in the east and south-west (Al... more France has a large variety of landscapes, including high mountains in the east and south-west (Alps, Pyrenees) and extensive plains and plateaux of the Aquitaine and the Paris basins open to the west, with altitudes mostly below 200 m. Ancient Hercynian massifs lie around their rims. Among them, the Vosges and the Massif Central were thrown outwards at the time of uplifting of the Alpine range. The Massif Central contains many volcanoes. Massifs of the Tertiary Period (Jura, Pre-Alps) are made up of folded sedimentary rock, mainly limestone. Main river valleys mark the eastern part with the Rhone valley that opens towards the Mediterranean and, in the north, the western part of the upper Rhine floodplain.
Spatial cultivar deployment and residue management : what impact for phoma stem canker of winter oilseed rape and resistance sustainability?
Meta-modelling of the impacts of regional cropping system scenarios for phoma stem canker control
European Journal of Agronomy, 2015
Estimation of erosion and sediment export from an agricultural catchment (1960-2000) confronting the outputs of an expert-based model and Cs-137 inventories
Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentatio... more Soil erosion leads to important environmental problems (e.g. muddy floods, reservoir sedimentation) in cultivated areas of the European loess belt. This study aimed to quantify erosion and to determine the impact of rainfall seasonality and land use change on soil erosion over the last 40 years in a 94-ha cultivated catchment of Normandy (France). To this end, scenarios representative of
Grass covers as tools for the reduction of soil losses by water erosion (a synthesis of knowledge and of information gained in Upper Normandy)
In loamy areas of Northern Europe, soil erosion is a widespread phenomenon, despite low rainfall ... more In loamy areas of Northern Europe, soil erosion is a widespread phenomenon, despite low rainfall intensity and a gentle topography. Interactions between meteorological conditions, farming operations and topsoil texture bring about rapid and significant changes in the hydraulic properties of topsoil.
Soil and Tillage Research, 2002
In the Normandy region of France, two extreme runoff events took place during winter of 1999 and ... more In the Normandy region of France, two extreme runoff events took place during winter of 1999 and spring of 2000 that caused ooding and considerable on-site as well as off-site damages. After each event, erosion damage was mapped on an experimental cultivated catchment (94 ha). The location and extent of rill, ephemeral gullies and deposits were measured. For each ®eld, information on land use and soil surface characteristics were also collected. Since 1991, when experimental work and survey campaigns were initiated on this catchment, interrill erosion dominated over rill or ephemeral gully erosion. Our objective was to link information on topography, soil surface characteristics, and land use with intensity and type of erosion that developed. Erosion features that were most related to topographic attributes and hence less affected by seasonal variations were ephemeral gullies and some prede®ned deposit types. Topographic attributes alone were not suf®cient to determine development of rill erosion, due to seasonal differences in vegetative cover. At the catchment scale, total erosion varied from 10 t/ha in December with 93% of the catchment area with vegetation cover 20%; to 1.5 t/ha in May, with 73% of the catchment area with vegetation cover >60%. The relative importance of ephemeral gully erosion out of total linear erosion varied from ca. 24% for the rainfall events of December to more than ca. 83% for the rainfall events of May. These results also highlight the fact that average annual sediment delivery as well as the relative importance of different erosion forms at the catchment scale cannot be generalised. Erosion prediction and erosion assessment risks are strongly dependent on catchment land use, morphology and storm characteristics. #
Effects of tillage on runoff directions: consequences on runoff contributing area within agricultural catchments
Journal of Hydrology, 1998
In areas of intensive agriculture, e.g. ‘Pays de Caux’ in France, which was the study area, field... more In areas of intensive agriculture, e.g. ‘Pays de Caux’ in France, which was the study area, field observations have shown that runoff directions were modified by agricultural activities. In order to account for factors responsible for modifications of the runoff direction (roughness, tillage direction and agricultural patterns, e.g. dead furrow or dirt tracks), we constructed a discriminant function based on field observations. This function enables us to decide whether flow direction for slopes of up to 15% was imposed by slope direction or tillage direction. It can be applied to any location, provided there are known roughness, known slope intensity, known aspect and known tillage azimuth.In order to examine the effects of these agricultural activities at the catchment scale, we compared two models by analysing the same hydrological variables: the area contributing to runoff and the flow network. The first model (Topo) was built according to the runoff direction derived from a Digital Elevation Model (DEM). The second model (Tillage) was constructed by combining information from the DEM, and information from rules based on field observations or resulting from statistical analysis.For 23 basic catchments, the result of the comparison between the two models (Topo and Tillage) showed that a major part of the catchments and the drainage network was affected by modifications related to the introduction of man-made agricultural factors. For example, for 20 of 23 catchments, the runoff flows over more than 50% of the surface of such areas were produced along the direction imposed by tillage. The introduction of tillage effect brings about modifications of both the shape and size of catchments.
Erosion and sediment budget across scale: A case study in a catchment of the European loess belt
Journal of Hydrology, 2012
... 2. Theoretical relationship between spatial scale and published mean sediment concentration d... more ... 2. Theoretical relationship between spatial scale and published mean sediment concentration derived from erosion rates in agricultural temperate areas of North-western Europe (over the loess belt), for arable lands with slopes between 2 and 5% ( (1) Fox and Bryan, 1999-(2 ...
International Journal of Sustainable Development, 2004
Runoff disregards territorial boundaries, affects farmers as well as other users of space, and ne... more Runoff disregards territorial boundaries, affects farmers as well as other users of space, and necessitates collective action if it is to be combatted. In this article, based on the case of Upper-Normandy, we show that geographical proximity can play a determining role in the struggle against erosive runoff, and we present a new tool for analysing relations of proximity between farmers. First we use three examples to show that farmers have only limited knowledge of the problem of erosion and are largely incapable of carrying out concerted collective action. That is why Syndicats de bassins versants were set up to provide organized proximity. Then we present a new tool for analysing relations of geographical proximity between farmed land and farmsteads, in order to assess the possibilities of coordination between farmers within catchment areas. Our results, based on the characterization of 1409 communes, clearly show that long distances, the size of farmed agricultural land and the high number of external farmers constitute major obstacles to the creation of ad hoc cooperative processes.
Earth Surface Processes and Landforms, 2002
A database composed of 673 natural rainfall events with sediment concentration measurements at th... more A database composed of 673 natural rainfall events with sediment concentration measurements at the field or plot scale was analysed. Measurements were conducted on similar soil type (loess soils prone to sealing phenomenon) to apprehend the variability and complexity involved in interrill erosion processes attributable to soil surface conditions. The effects of the dominant controlling factors are not described by means of equations; rather, we established a classification of potential sediment concentration domain according to combination of the dominant parameters. Thereby, significant differences and evolution trends of mean sediment concentration between the different parameter categories are identified. Further, when parameter influences interact, it allows us to discern the relative effects of factors according to their respective degree of expression. It was shown that crop cover had a major influence on mean sediment concentration, particularly when soil surface roughness is low and when maximum 6-min intensity of rainfall events exceeds 10 mm h 1 : mean sediment concentration decreases from 8Ð93 g l 1 for 0-20 per cent of coverage to 0Ð97 g l 1 for 21-60 per cent of coverage. The established classification also indicates that the increase of the maximum 6-min intensity of the rainfall factor leads to a linear increase of mean sediment concentration for crop cover over 21 per cent (e.g. from 2Ð96 g l 1 to 14Ð44 g l 1 for the 1-5 cm roughness class) and to an exponential increase for low crop cover (e.g. from 3Ð92 g l 1 to 58Ð76 g l 1 for the 1-5 cm roughness class). The implication of this work may bring perspective for erosion prediction modelling and give references for the development of interrill erosion equation.
CATENA, 2005
Over the last 30 years, European agricultural policy has influenced agricultural practices. These... more Over the last 30 years, European agricultural policy has influenced agricultural practices. These have led to an increase in numerous environmental issues such as the erosion and runoff risk, which have reached an alarming level in loamy soils of Upper Normandy. To control runoff and erosion at catchment scale, public authorities need tools in order to obtain a better knowledge of present or future pressure on the environment. With such information, it will be easier to act locally on a problem by avoiding negative impacts elsewhere in the area.
CATENA, 2005
Global climate has changed over the past century. Precipitation amounts and intensities are incre... more Global climate has changed over the past century. Precipitation amounts and intensities are increasing. In this study we investigated the response of seven soil erosion models to a few basic precipitation and vegetation related parameters using common data from one humid and one semiarid watershed. Perturbations were made to inputs for rainfall intensities and amounts, and to ground surface cover and canopy cover. Principal results were that: soil erosion is likely to be more affected than runoff by changes in rainfall and cover, though both are likely to be significantly impacted; percent erosion and runoff will likely change more for each percent change in rainfall intensity and amount than to each percent change in either canopy or ground cover; changes in rainfall amount associated with changes in storm rainfall intensity will likely have a greater impact on runoff and erosion than simply changes in rainfall amount alone; changes in ground cover have a much greater impact on both runoff and erosion than changes in canopy cover alone. The results do not imply that 0341-8162/$ -see front matter D .gov (M.A. Nearing).
CATENA, 2005
Extensive soil surface observations and measurements were conducted in Normandy on loess soils pr... more Extensive soil surface observations and measurements were conducted in Normandy on loess soils prone to surface crusting in order to understand the spatial distribution and temporal variability of soil surface characteristics involved in erosion processes. A database composed of more than 5000 soil surface observations at the field or plot scale was analysed. We classified these observations according to combinations of three dominant factors: crusting stage, roughness and crop cover. Frequency analysis showed that three combinations of these factors accounted for more than 50% of the total observations. Eight other combinations accounted each for more than 2% of the observations. These dominant and secondary combinations are considered as breference surface conditionsQ. Their potential range of the infiltration capacity and sediment production were estimated from field measurements under natural and simulated rainfall. For the loess soils in our study, mean field infiltration capacity ranged between 2 mm/h and 50 mm/h while mean sediment concentration ranged between 0.5 g/l and 30 g/l for the different combinations of soil surface and rainfall characteristics. This work, based on a local case study, allowed the development of a new approach for erosion prediction modelling (STREAM) which could be transferable to other areas where Hortonian processes are dominant. D
CATENA, 2003
This paper describes a new erosion model to predict the location and volume of ephemeral gullies ... more This paper describes a new erosion model to predict the location and volume of ephemeral gullies within the main runoff collector network of agricultural catchments. This model, using an expert-based approach, combines field experiment results and knowledge about erosion processes and agricultural practices. It takes into account slope gradient, parameters reducing runoff flow velocity or increasing soil resistance (land use, plant cover percentage, roughness and soil surface crusting stage), the hydrological structure of catchments and the runoff volume. The model is used to calculate the soil sensitivity to ephemeral gully erosion at any point in four small cultivated catchments.