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1.
During the last decades, the European loess belt has been confronted with a significant increase in environmental problems due to erosion on agricultural land. Spatially distributed runoff and erosion models operating at the catchment scale are therefore needed to evaluate the impact of potential mitigation measures. Expert-based models offer an alternative solution to process-based and empirical models, but their decision rules are only valid for the local conditions for which they have been derived. The STREAM model, which was developed in Normandy (France), has been applied in two Belgian catchments having a similar soil texture, as well as in a catchment of southern France differing by soil, land use and climate characteristics. The performance of hydrological models can be assessed for instance by calculating the Nash–Sutcliffe efficiency criterion (ENS). When applied to Belgium, the model results are satisfactory to good after an adaptation of the decision rules (0.90 < ENS < 0.93 for runoff predictions and 0.85 < ENS < 0.89 for erosion predictions). Given the important environmental differences between Normandy and southern France, the model rules were also adapted for application in the latter environment. Unfortunately, the quality of runoff predictions was insufficient to simulate erosion in southern France. In conclusion, STREAM is a reliable model providing satisfactory runoff and erosion predictions in the regions where hortonian overland flow dominates. Nevertheless, an adaptation of decision rules based on local multi-scale (plot, field, catchment) data is needed, before running the model. STREAM can then serve as a decision support tool to design for instance flood control measures.  相似文献   
2.
Journal of Soils and Sediments - Erosion and its spatial distribution in three agricultural headwater catchments were assessed in the border of the volcanic plateau in Southern Brazil. We analyzed...  相似文献   
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4.
This study examines the level of mercury contamination for different components of the biosphere in French Guiana. The spatial variability of the contamination of the waters, soils and sediments in the catchment area of the Sinnamary River is studied. The contamination of the trophic chain isdiscussed by analysis of the flesh of fish for the principal species represented in nine Guianese rivers, especially species consumed by human populations. The mercury contamination of sediments and soils, is extremely heterogeneous and that of fish is generalised. For carnivorous fish, the average mercury content is 0.48 μg g-1 (±0.28) (fresh weight) and for non-carnivorous species, 0.05 μg g-1 (±0.07). The concentrationsmeasured are greater than the European standards forconsumption for 4.7% of the carnivorous individuals.  相似文献   
5.
Mapping and monitoring linear erosion features (LEFs) over large areas is fundamental for a better understanding of the main erosion processes and for planning suitable protection measures. The advent of very high‐resolution satellite imagery has expanded the range of satellite LEF identification to moderate‐size elements. After determining the relationship between satellite imagery resolution and the ability to detect LEFs, we discuss a highly automated method for extracting such LEFs from a very high spatial resolution image (0.61 m resolution). The method is based on a two‐stage strategy: (1) extraction of all linear features visible on the satellite image using filters and photo‐interpretation; (2) filtering these linear features according to geometric criteria (e.g. orientation relative to slope, sinuosity, position in landscape, etc.) so as to retain only those relative to linear erosion. A series of three images with increasing spatial resolution (10.5 and 0.61 m) was prepared for an area on the Cap Bon peninsula (Tunisia). This predominantly agricultural area has a high density of LEFs with very varied geometric characteristics. The area's problems are both onsite for the agriculture itself, and offsite with the silting up of hillside reservoirs. Respectively 22 per cent, 37 per cent and 73 per cent of the site's LEFs, with respective average widths of 2.8, 3.0 and 2.2 m, are visible on the 10, 5 and 0.61 m resolution images. Gully identification should help to identify the most threatened areas to help land use planning and management or to validate erosion models whether at regional or local (drainage basin) scale. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
6.
Water erosion of cropland constitutes an issue for natural environments along runoff flowpaths due to property damage by soil-laden water and the associated transfer of nutrients and pesticides. In the Pays de Caux region of northwestern France, the silty soils with crusting properties induce a high risk of runoff and erosion. Changes in agricultural practices, land use and landscape patterns appear to have increased the occurrence of erosion and mud flows over the past few decades.A runoff and erosion model called STREAM, applicable to single rainfall events at catchment scale, has been developed to simulate the impacts of land-use modifications. The model takes into account processes that degrade surface states when calculating infiltration rates, as well as agricultural aspects when computing the runoff circulation network. STREAM is based on an expert-system approach that focuses on the dominant processes whilst having only a few input parameters: three of these are used to determine the runoff circulation network, and the other four to calculate infiltration rates. Input nevertheless requires field observations, which restricts application of the model to small catchments.Satellite data covering large areas is considered as an alternative input for such a model, the main objectives being to adapt STREAM accordingly, and to compare the obtained results with field data. In view of previous work involving the extraction and validation of roughness indices using RADARSAT data, this study is based on RADARSAT and LANDSAT TM data collected during the winter of 1998.After adaptation to receive remote-sensing data, the resulting STREAM-TED model requires less input, namely (1) slope and orientation, (2) land-use classification from optical remote-sensing data, (3) roughness indices from radar remote-sensing data, and (4) previous rainfall.Runoff volumes at a gauged catchment outlet (Bourville in Upper Normandy, France) are simulated by four successive versions of the model ranging from the original STREAM to the adapted STREAM-TED. Predictions of the four versions are compared, and performance of the successive simulations is assessed in relation to measured values and according to five statistical indices.Predictions of runoff volume at the catchment outlet using STREAM-TED are similar to those using the original STREAM model, but with a tendency towards overestimation. The final STREAM-TED version is capable of identifying areas sensitive to runoff within a group of catchments and could be used as a planning decision tool in the implementation of conservation practices.  相似文献   
7.

Background, aim, and scope  

Sediment fluxes within continental areas play a major role in biogeochemical cycles and are often the cause of soil surface degradation as well as water and ecosystem pollution. In a situation where a high proportion of the land surface is experiencing significant global land use and climate changes, it appears important to establish sediment budgets considering the major processes forcing sediment redistribution within drainage areas. In this context, the aim of this study is to test a methodology to estimate a sediment yield index at a large spatial resolution for European river basins.  相似文献   
8.
This study was conducted in Champagne vineyards in France, and the objectives were to compare the main cultivation practices in Champagne vineyards and to specify the conditions required for the optimum effect of inter‐row grass cover on runoff and erosion in experimental plots of 0.25 m² under simulated rainfall. Three types of ground cover were studied. In the bark‐and‐vine‐prunings plots, the runoff coefficient (RC) ranged from 1.3 to 4.0% and soil losses were <1 g/m2/h. In the bare soil (BS) plot, the highest RC of the study was found (80.0%) and soil losses reached 7.4 g/m2/h. In the grass cover plots, the RC and amount of eroded soil were highly variable: the RCs ranged from 0.4 to 77.0%, and soil losses were between less than 1 and 13.4 g/m2/h. Soil type, soil moisture, slope and agricultural practices did not account for the variability. In fact, the density of grass cover in the wheel tracks explained a portion of this variability. The lack of grass in the centre of the inter‐row allowed for a preferential flow and created an erosion line in the wheel tracks where the soil was compacted. This study showed that grass cover in a vineyard was not necessarily sufficient to reduce surface runoff and prevent soil erosion. To be effective, the grass cover must be dense enough in the wheel tracks of agricultural machinery to avoid RCs close to the RC achieved with BS.  相似文献   
9.
This paper gives a brief synthesis of the information obtainable from remote-sensing data and how it can be related to two significant functions of catchment hydrology, namely, the processes of production and transfer. After presenting examples of the type of information that can be derived from remote sensing (characterisation of soil surface by different wavelengths, temporal changes of surface states, incision and geometry of possible water pathways on the surface, etc.), we examine how this information can provide parameters for input into runoff and erosion models. Finally, we assess the progress in assimilating remote-sensing data into deterministic models of storm runoff.  相似文献   
10.
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