H. Squividant

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 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...

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 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 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 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

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.

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 technical systems which monitor runoff mecanisms are mainly managed at the plot scale. For better visualization and understanding of the influence of agricultural practices and managements on water and pesticides transfers by runoff mecanisms, a drainage model based on plot relationships was developed. plots are divided in several contributory areas which make it possible to follow runoff water ways through plots : inlets and outlets of plot and their associated contributory surfaces are identified. This model of drainage is calculated taking in account a digital elevation model (DEM) and spatial informations imported from a geographical information system (GIS) and describing the plot system, land use, landcover, soil surface condition, hedges and grass strip, ditches and hydrographic network. In a first stage, the flow direction is calculated in a traditionnal way, taking in account slope direction calculated from the DEM. In a second stage, calculated run-off flow direction is modified taking in account surface managements (mainly hedges and ambankment, ditches and hydrographic network). And in a third stage, plot outlets are linked together using a tree structure and plots are themselves linked together using a graph structure. Pesticides run-off flows are calculated using the outlet tree structure and then summerized from plot to plot using the plot graph. This model is tested on a catchment area of 17 km2 including a few hundreds of field.