Le programme Base de Données des Analyses de Terre (BDAT) regroupe depuis vingt ans les résultats... more Le programme Base de Données des Analyses de Terre (BDAT) regroupe depuis vingt ans les résultats d'analyses d'horizons de surface de sols cultivés, effectuées sur l'ensemble du territoire national, à la demande d'agriculteurs, par des laboratoires agréés par le Ministère en charge de l'agriculture. Cet article a pour objectif de présenter les derniers résultats produits par ce programme. Il aborde successivement la présentation de l'organisation du programme, des développements méthodologiques connexes et des principaux résultats sur le statut et l'évolution des propriétés des horizons de surface des sols cultivés. A ce jour, la BDAT recense 22 830 147 résul-tats analytiques provenant de 1 962 238 échantillons récoltés sur la période 1990-2009. L'analyse de ces données permet par exemple de mettre en évidence à l'échelle nationale une forte hétérogénéité spatiale de la richesse en phosphore assimilable, des baisses des teneurs en carbone des sols...
Le projet Websol est une interface Web qui permet de promouvoir et de faciliter la mise à disposi... more Le projet Websol est une interface Web qui permet de promouvoir et de faciliter la mise à disposition et la valorisation des connaissances sur les sols (RRP 1 notamment) auprès des nombreux utilisateurs potentiels régionaux (techniciens, conseillers, administrations, etc.) et territoriaux (collectivités, contrats de rivières, etc.), ainsi que, pour partie de ces données, auprès du grand public. Cette interface est maintenant finalisée dans sa première version 2 dans le cadre du projet CASDAR 3 2007-2010. La plateforme a pour vocation la valorisation aussi bien des données pédologiques que des applications réalisées à partir de ces données. Le développement de nouveaux modules élargira encore le champ des valorisations. Pour aider à son implantation chez les partenaires impliqués dans le programme IGCS 4 , et veiller à son évolution en la dotant de nouvelles fonctionnalités, la plateforme Websol est mise à disposition (droits de propriété et codes sources) du RMT « Sols et Territoire...
Knowledge of the spatial distribution of wetlands within landscapes is needed for a number of dif... more Knowledge of the spatial distribution of wetlands within landscapes is needed for a number of different purposes as non-point pollution control, aquatic life, flood protection or sediment traps or sources. The purpose of this paper was to propose and to test a parsimonious method for predicting wetlands in small catchments across a wide range of geological, topographic and climatic conditions. A climato-topographic index has been derived from the topographic index-taking into account the local slope and the upslope drainage area, first proposed by Beven and Kirkby [Hydrol. Sci. Bull. 24 (1979) 43]. This new index takes into account the effective rainfall, in addition to topographic factors, in order to achieve a prediction of wetland occurrence for places with different rainy conditions. The two indexes were compared. Six study areas were selected representing a wide range of climate, geology and geomorphology across Europe. The wetland area ranges from 1 to 30% of the total area for the different catchments, and the annual effective rainfall from 67 to 592 mm. The climato-topographic index seems able to predict the structure and general areal extent of wetlands without any local calibration of the model, except where the permeability of the soil surface is important and very different from the other sites considered. The climato-topographic index gives a classification of wetland occurrence similar to the field data. The exact location of the wetland is often poorly predicted, but this is mostly due to the current poor quality of the Digital Terrain Model. Thus, there is currently a technical limitation to the use of the approach advocated here.
Des éléments sont proposés pour l'élaboration d'une méthode d'évaluation d'un ris... more Des éléments sont proposés pour l'élaboration d'une méthode d'évaluation d'un risque parcellaire de contamination des eaux superfi-cielles par les pesticides. Cette méthode suit les étapes suivantes : (1) une liste hiérarchisée de facteurs de risque est établie, faisant pour partie suite à une consultation d'experts régionaux et nationaux ; (2) chaque facteur de risque est traduit en un critère mesurable à l'échelle de la parcelle, plusieurs critères étant évaluables directement sous système d'information géographique à partir du parcellaire, des données d'occupation du sol et d'un modèle numérique de terrain ; (3) chaque facteur est subdivisé en deux, trois ou quatre moda-lités, les limites entre ces modalités s'appuyant là aussi pour partie sur l'avis des experts ; (4) la technique de combinaison des facteurs de risque choisie est une technique hiérarchique de rang, la méthode SIRIS, déjà utilisée pour classer les molécules de pesticides...
The proposal in this paper is to make accessible the hydrology analysis tools that were developed... more The proposal in this paper is to make accessible the hydrology analysis tools that were developed by our research team in the past years through an interoperable Spatial Data Infrastructure. To this aim we chose to develop add-ons for the geOrchestra OGC-compliant platform. Such add-ons trigger algorithms and retrieve their output in real time through OGC standard WPS. We then introduce a watershed WPS add-on and its functioning modes. In so doing we exemplify the fact that the use of OGC standards make it straightforward (and transparent to the user operating a common web browser) to remotely trigger a process on a distant server, then apply it to distant data present on a remote cartographic server, and drop the outcome onto a third-party cartographic server while visualizing it all on a browser. Key words OGC standards; Web Processing Service; add-on; Spatial Data Infrastructure; geOrchestra; hydrological modelling; watershed; MNTSurf.
In France, farmers commission about 250,000 soil-testing analyses per year to assist them managin... more In France, farmers commission about 250,000 soil-testing analyses per year to assist them managing soil fertility. The number and diversity of origin of the samples make these analyses an interesting and original information source regarding cultivated topsoil variability. Moreover, these analyses relate to several parameters strongly influenced by human activity (macronutrient contents, pH...), for which existing cartographic information is not very relevant. Compiling the results of these analyses into a database makes it possible to re-use these data within both a national and temporal framework.A database compilation relating to data collected over the period 1990-2009 has been recently achieved. So far, commercial soil-testing laboratories approved by the Ministry of Agriculture have provided analytical results from more than 2,000,000 samples. After the initial quality control stage, analytical results from more than 1,900,000 samples were available in the database. The anonymity of the landholders seeking soil analyses is perfectly preserved, as the only identifying information stored is the location of the nearest administrative city to the sample site.We present in this dataset a set of statistical parameters of the spatial distributions for several agronomic soil properties. These statistical parameters are calculated for 4 different nested spatial entities (administrative areas: e.g. regions, departments, counties and agricultural areas) and for 4 time periods (1990-1994, 1995-1999, 2000-2004, 2005-2009). Two kinds of agronomic soil properties are available: the firs one correspond to the quantitative variables like the organic carbon content and the second one corresponds to the qualitative variables like the texture class. For each spatial unit and temporal period, we calculated the following statistics stets: the first set is calculated for the quantitative variables and corresponds to the number of samples, the mean, the standard deviation and, the 2-,4-,10-quantiles; the second set is calculated f [...]
Models were usually developed to understand non point source pollution by pesticides in cultivate... more Models were usually developed to understand non point source pollution by pesticides in cultivated catchments. These models whose purpose is often to estimate transfers towards the river, highlight the role of agricultural practices and managements. These models are generally based on a space discretization per pixel, pixel whose size varies according to the scale of integration. However, managements, farming and
To-date, the commonest way to deal with geographical information and processes still appears to c... more To-date, the commonest way to deal with geographical information and processes still appears to consume local resources, i.e. locally stored data processed on a local desktop or server. The maturity and subsequent growing use of OGC standards to exchange data on the World Wide Web, enhanced in Europe by the INSPIRE Directive, is bound to change the way people (and among them research scientists, especially in environmental sciences) make use of, and manage, spatial data. A clever use of OGC standards can help scientists to better store, share and use data, in particular for modelling. We propose a framework for online processing by making an intensive use of OGC standards. We illustrate it using the Spatial Data Infrastructure (SDI) GéoSAS which is the SDI set up for researchers' needs in our department. It is based on the existing open source, modular and interoperable Spatial Data Architecture geOrchestra.
ABSTRACT The prediction of wetlands at the national scale is fundamental to design and implement ... more ABSTRACT The prediction of wetlands at the national scale is fundamental to design and implement consistent national policies in order to preserve these fragile but essential ecosystems involved in the production of many fundamental ecosystem services. Depending on the topographic situation, the occurrence of potential wetlands is mostly driven by geomorphology and rainfall and the vertical distance to the channel network. This study aims to test for France the nationwide implementation of a method based on a topo-climatic index in combination with the vertical distance to the channel network to predict the spatial distribution of potential wetlands. Following the PEEW approach used in this study (based on potential, existing, and efficient wetland functional assessment), potential wetlands include all geographical situations where geomorphological and/or climatic criteria may entail high probability of wetland occurence. Potential wetlands include therefore former wetlands areas destructed by artificial drainage and river straightening for example. Topo-climatic index and the vertical distance to the channel network were calculated nationwide. To determine the threshold of these indices, France was stratified in hydroecoregions, based on geology, climate, topography, vegetation and channel network density. Within each hydroecoregion, cumulative frequencies of the topo-climatic index were calculated and a threshold was determined according to pedological data (percentage of hydromorphic soils) available in the area and using a probabilistic approach, whereas the threshold of the vertical distance to the channel network was computed alongside the potential flood zone. Both were combined according to a decision tree based on permeability of the soil surface and topographic situations in order to get a national prediction of the location of potential wetlands. Results were validated against point-specific soil data and detailed soil maps. Combination of climato-topographic index and the vertical distance to the channel network was better at predicting the nationwide spatial distribution of wetlands with a highly improved accuracy by comparison with monofactorial modelling. The first validation test using point-specific soil data were satisfactory, the overall accuracy of validation equaled 67.8%, the accuracy for potential wetlands equaled 54.6% and the Kappa index amounted to 0.17. The accuracy seems to be poor for areas where few soil data were available to determine the threshold, thus stressing the need for further acquisition of soil data. The potential of this strategy to predict wetlands over large areas was therefore confirmed.
A topological representation of a rural catchment is proposed here in addition to the generally u... more A topological representation of a rural catchment is proposed here in addition to the generally used topographic drainage network. This is an object-oriented representation based on the identification of the inlets and outlets for surface water flow on each farmer's field (or plot) and their respective contributing areas and relationships. It represents the catchment as a set of independent plot outlet trees reaching the stream, while a given plot outlet tree represents the pattern of surface flow relationships between individual plots. In the present study, we propose to implement functions related to linear and surface elements of the landscape, such as hedges or road networks, or land use, to obtain what we call a landscape drainage network which delineates the effective contributing area to the stream, thus characterizing its topological structure. Landscape elements modify flow pathways and/or favour water infiltration, thus reducing the area contributing to the surface yield and modifying the structure of the plot outlet trees. This method is applied to a 4Ð4-km 2 catchment area comprising 43 955 pixels and 312 plots. While the full set of 164 plot outlet trees, with an average of 7 plots per tree, covers 100% of the total surface area of the catchment, the landscape drainage network comprises no more than 37 plot outlet trees with an average of 2 plots per tree, accounting for 52 and 7% of the catchment surface area, when taking account of linear elements and land use, respectively. This topological representation can be easily adapted to changes in land use and land infrastructure, and provides a simple and functional display for intercomparison of catchments and decision support regarding landscape and water management.
Le programme Base de Données des Analyses de Terre (BDAT) regroupe depuis vingt ans les résultats... more Le programme Base de Données des Analyses de Terre (BDAT) regroupe depuis vingt ans les résultats d'analyses d'horizons de surface de sols cultivés, effectuées sur l'ensemble du territoire national, à la demande d'agriculteurs, par des laboratoires agréés par le Ministère en charge de l'agriculture. Cet article a pour objectif de présenter les derniers résultats produits par ce programme. Il aborde successivement la présentation de l'organisation du programme, des développements méthodologiques connexes et des principaux résultats sur le statut et l'évolution des propriétés des horizons de surface des sols cultivés. A ce jour, la BDAT recense 22 830 147 résul-tats analytiques provenant de 1 962 238 échantillons récoltés sur la période 1990-2009. L'analyse de ces données permet par exemple de mettre en évidence à l'échelle nationale une forte hétérogénéité spatiale de la richesse en phosphore assimilable, des baisses des teneurs en carbone des sols...
Le projet Websol est une interface Web qui permet de promouvoir et de faciliter la mise à disposi... more Le projet Websol est une interface Web qui permet de promouvoir et de faciliter la mise à disposition et la valorisation des connaissances sur les sols (RRP 1 notamment) auprès des nombreux utilisateurs potentiels régionaux (techniciens, conseillers, administrations, etc.) et territoriaux (collectivités, contrats de rivières, etc.), ainsi que, pour partie de ces données, auprès du grand public. Cette interface est maintenant finalisée dans sa première version 2 dans le cadre du projet CASDAR 3 2007-2010. La plateforme a pour vocation la valorisation aussi bien des données pédologiques que des applications réalisées à partir de ces données. Le développement de nouveaux modules élargira encore le champ des valorisations. Pour aider à son implantation chez les partenaires impliqués dans le programme IGCS 4 , et veiller à son évolution en la dotant de nouvelles fonctionnalités, la plateforme Websol est mise à disposition (droits de propriété et codes sources) du RMT « Sols et Territoire...
Knowledge of the spatial distribution of wetlands within landscapes is needed for a number of dif... more Knowledge of the spatial distribution of wetlands within landscapes is needed for a number of different purposes as non-point pollution control, aquatic life, flood protection or sediment traps or sources. The purpose of this paper was to propose and to test a parsimonious method for predicting wetlands in small catchments across a wide range of geological, topographic and climatic conditions. A climato-topographic index has been derived from the topographic index-taking into account the local slope and the upslope drainage area, first proposed by Beven and Kirkby [Hydrol. Sci. Bull. 24 (1979) 43]. This new index takes into account the effective rainfall, in addition to topographic factors, in order to achieve a prediction of wetland occurrence for places with different rainy conditions. The two indexes were compared. Six study areas were selected representing a wide range of climate, geology and geomorphology across Europe. The wetland area ranges from 1 to 30% of the total area for the different catchments, and the annual effective rainfall from 67 to 592 mm. The climato-topographic index seems able to predict the structure and general areal extent of wetlands without any local calibration of the model, except where the permeability of the soil surface is important and very different from the other sites considered. The climato-topographic index gives a classification of wetland occurrence similar to the field data. The exact location of the wetland is often poorly predicted, but this is mostly due to the current poor quality of the Digital Terrain Model. Thus, there is currently a technical limitation to the use of the approach advocated here.
Des éléments sont proposés pour l'élaboration d'une méthode d'évaluation d'un ris... more Des éléments sont proposés pour l'élaboration d'une méthode d'évaluation d'un risque parcellaire de contamination des eaux superfi-cielles par les pesticides. Cette méthode suit les étapes suivantes : (1) une liste hiérarchisée de facteurs de risque est établie, faisant pour partie suite à une consultation d'experts régionaux et nationaux ; (2) chaque facteur de risque est traduit en un critère mesurable à l'échelle de la parcelle, plusieurs critères étant évaluables directement sous système d'information géographique à partir du parcellaire, des données d'occupation du sol et d'un modèle numérique de terrain ; (3) chaque facteur est subdivisé en deux, trois ou quatre moda-lités, les limites entre ces modalités s'appuyant là aussi pour partie sur l'avis des experts ; (4) la technique de combinaison des facteurs de risque choisie est une technique hiérarchique de rang, la méthode SIRIS, déjà utilisée pour classer les molécules de pesticides...
The proposal in this paper is to make accessible the hydrology analysis tools that were developed... more The proposal in this paper is to make accessible the hydrology analysis tools that were developed by our research team in the past years through an interoperable Spatial Data Infrastructure. To this aim we chose to develop add-ons for the geOrchestra OGC-compliant platform. Such add-ons trigger algorithms and retrieve their output in real time through OGC standard WPS. We then introduce a watershed WPS add-on and its functioning modes. In so doing we exemplify the fact that the use of OGC standards make it straightforward (and transparent to the user operating a common web browser) to remotely trigger a process on a distant server, then apply it to distant data present on a remote cartographic server, and drop the outcome onto a third-party cartographic server while visualizing it all on a browser. Key words OGC standards; Web Processing Service; add-on; Spatial Data Infrastructure; geOrchestra; hydrological modelling; watershed; MNTSurf.
In France, farmers commission about 250,000 soil-testing analyses per year to assist them managin... more In France, farmers commission about 250,000 soil-testing analyses per year to assist them managing soil fertility. The number and diversity of origin of the samples make these analyses an interesting and original information source regarding cultivated topsoil variability. Moreover, these analyses relate to several parameters strongly influenced by human activity (macronutrient contents, pH...), for which existing cartographic information is not very relevant. Compiling the results of these analyses into a database makes it possible to re-use these data within both a national and temporal framework.A database compilation relating to data collected over the period 1990-2009 has been recently achieved. So far, commercial soil-testing laboratories approved by the Ministry of Agriculture have provided analytical results from more than 2,000,000 samples. After the initial quality control stage, analytical results from more than 1,900,000 samples were available in the database. The anonymity of the landholders seeking soil analyses is perfectly preserved, as the only identifying information stored is the location of the nearest administrative city to the sample site.We present in this dataset a set of statistical parameters of the spatial distributions for several agronomic soil properties. These statistical parameters are calculated for 4 different nested spatial entities (administrative areas: e.g. regions, departments, counties and agricultural areas) and for 4 time periods (1990-1994, 1995-1999, 2000-2004, 2005-2009). Two kinds of agronomic soil properties are available: the firs one correspond to the quantitative variables like the organic carbon content and the second one corresponds to the qualitative variables like the texture class. For each spatial unit and temporal period, we calculated the following statistics stets: the first set is calculated for the quantitative variables and corresponds to the number of samples, the mean, the standard deviation and, the 2-,4-,10-quantiles; the second set is calculated f [...]
Models were usually developed to understand non point source pollution by pesticides in cultivate... more Models were usually developed to understand non point source pollution by pesticides in cultivated catchments. These models whose purpose is often to estimate transfers towards the river, highlight the role of agricultural practices and managements. These models are generally based on a space discretization per pixel, pixel whose size varies according to the scale of integration. However, managements, farming and
To-date, the commonest way to deal with geographical information and processes still appears to c... more To-date, the commonest way to deal with geographical information and processes still appears to consume local resources, i.e. locally stored data processed on a local desktop or server. The maturity and subsequent growing use of OGC standards to exchange data on the World Wide Web, enhanced in Europe by the INSPIRE Directive, is bound to change the way people (and among them research scientists, especially in environmental sciences) make use of, and manage, spatial data. A clever use of OGC standards can help scientists to better store, share and use data, in particular for modelling. We propose a framework for online processing by making an intensive use of OGC standards. We illustrate it using the Spatial Data Infrastructure (SDI) GéoSAS which is the SDI set up for researchers' needs in our department. It is based on the existing open source, modular and interoperable Spatial Data Architecture geOrchestra.
ABSTRACT The prediction of wetlands at the national scale is fundamental to design and implement ... more ABSTRACT The prediction of wetlands at the national scale is fundamental to design and implement consistent national policies in order to preserve these fragile but essential ecosystems involved in the production of many fundamental ecosystem services. Depending on the topographic situation, the occurrence of potential wetlands is mostly driven by geomorphology and rainfall and the vertical distance to the channel network. This study aims to test for France the nationwide implementation of a method based on a topo-climatic index in combination with the vertical distance to the channel network to predict the spatial distribution of potential wetlands. Following the PEEW approach used in this study (based on potential, existing, and efficient wetland functional assessment), potential wetlands include all geographical situations where geomorphological and/or climatic criteria may entail high probability of wetland occurence. Potential wetlands include therefore former wetlands areas destructed by artificial drainage and river straightening for example. Topo-climatic index and the vertical distance to the channel network were calculated nationwide. To determine the threshold of these indices, France was stratified in hydroecoregions, based on geology, climate, topography, vegetation and channel network density. Within each hydroecoregion, cumulative frequencies of the topo-climatic index were calculated and a threshold was determined according to pedological data (percentage of hydromorphic soils) available in the area and using a probabilistic approach, whereas the threshold of the vertical distance to the channel network was computed alongside the potential flood zone. Both were combined according to a decision tree based on permeability of the soil surface and topographic situations in order to get a national prediction of the location of potential wetlands. Results were validated against point-specific soil data and detailed soil maps. Combination of climato-topographic index and the vertical distance to the channel network was better at predicting the nationwide spatial distribution of wetlands with a highly improved accuracy by comparison with monofactorial modelling. The first validation test using point-specific soil data were satisfactory, the overall accuracy of validation equaled 67.8%, the accuracy for potential wetlands equaled 54.6% and the Kappa index amounted to 0.17. The accuracy seems to be poor for areas where few soil data were available to determine the threshold, thus stressing the need for further acquisition of soil data. The potential of this strategy to predict wetlands over large areas was therefore confirmed.
A topological representation of a rural catchment is proposed here in addition to the generally u... more A topological representation of a rural catchment is proposed here in addition to the generally used topographic drainage network. This is an object-oriented representation based on the identification of the inlets and outlets for surface water flow on each farmer's field (or plot) and their respective contributing areas and relationships. It represents the catchment as a set of independent plot outlet trees reaching the stream, while a given plot outlet tree represents the pattern of surface flow relationships between individual plots. In the present study, we propose to implement functions related to linear and surface elements of the landscape, such as hedges or road networks, or land use, to obtain what we call a landscape drainage network which delineates the effective contributing area to the stream, thus characterizing its topological structure. Landscape elements modify flow pathways and/or favour water infiltration, thus reducing the area contributing to the surface yield and modifying the structure of the plot outlet trees. This method is applied to a 4Ð4-km 2 catchment area comprising 43 955 pixels and 312 plots. While the full set of 164 plot outlet trees, with an average of 7 plots per tree, covers 100% of the total surface area of the catchment, the landscape drainage network comprises no more than 37 plot outlet trees with an average of 2 plots per tree, accounting for 52 and 7% of the catchment surface area, when taking account of linear elements and land use, respectively. This topological representation can be easily adapted to changes in land use and land infrastructure, and provides a simple and functional display for intercomparison of catchments and decision support regarding landscape and water management.
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Papers by H. Squividant