An indicator approach for describing the spatial variability of artificial stream networks with regard to herbicide pollution in cultivated watersheds

Abstract Artificial stream networks play a major role in water and pollutant transfer within cultivated watersheds. Since the characteristics of these artificial stream network (e.g. width, vegetation cover, presence of sediments, etc.) are highly variable in space and in time, describing their variability appears as a prerequisite for assessing environmental risk of pollution at watershed scale. In this perspective an indicator approach is presented which includes three steps: (a) collecting properties of reach (i.e. elementary stream) along an artificial stream networks by means of a field and GIS-based approach, (b) deriving from these properties a set of quantitative indicators of hydrological and chemical processes involved in herbicide transfer, (c) classifying reaches in terms of their role in herbicide transfers on the basis of these indicators. The application of this method to three different watersheds located in France – Roujan watershed (South), La Morcille (East-Centre) and Le Cetrais (North-West) – confirms that artificial stream networks of cultivated watersheds are highly spatially variable in regard to pollutant transfer. This spatial variability includes both variations between the watersheds and variations within the watersheds. Furthermore, the study reveals that the stream network properties can also be variable in time.

[1]  Christian Bockstaller,et al.  Comparison and evaluation of eight pesticide environmental risk indicators developed in Europe and recommendations for future use , 2002 .

[2]  M. Voltz,et al.  Effects of the spatial organization of agricultural management on the hydrological behaviour of a farmed catchment during flood events , 2001 .

[3]  Nadia Carluer,et al.  Assessment and modelling of the influence of man-made networks on the hydrology of a small watershed: implications for fast flow components, water quality and landscape management , 2004 .

[4]  B. Laillet,et al.  Rétention des produits phytosanitaires dans les fossés de connexion parcelle-cours d'eau , 2003 .

[5]  A. N. Strahler.  Quantitative geomorphology of drainage basin and channel networks , 1964 .

[6]  R. Grayson,et al.  Phosphorus uptake and release in surface drains , 2003 .

[7]  Marc Voltz,et al.  Oryzalin fate and transport in runoff water in Mediterranean vineyards. , 2004, Chemosphere.

[8]  P. Burrough.  Principles of Geographical Information Systems for Land Resources Assessment , 1986 .

[9]  Philippe Lagacherie,et al.  Effects of DEM data source and sampling pattern on topographical parameters and on a topography-based hydrological model , 1996 .

[10]  C. M. Cooper,et al.  Vegetative and structural characteristics of agricultural drainages in the Mississippi Delta landscapes. , 2004, Environmental pollution.

[11]  Jeffrey G. Arnold,et al.  Application of geographic information systems in hydrology and water resources management: K. Kovar and H.P. Nachtnebel (editors), Institute of Hydrology, Wallingford, UK, 1993, 694 + xii pp., US$ 80.00, ISBN 0-947571-48-5 , 1995 .

[12]  Philippe Lagacherie,et al.  Modelling Spatial Variability Along Drainage Networks with Geostatistics , 2006 .

[13]  J. Sukias,et al.  Phosphorus fractions and retention in drainage ditch sediments receiving surface runoff and subsurface drainage from agricultural catchments in the North Island, New Zealand , 2002 .

[14]  Charles M. Cooper,et al.  Transport and fate of atrazine and lambda-cyhalothrin in an agricultural drainage ditch in the Mississippi Delta, USA , 2001 .

[15]  P. Burrough,et al.  Principles of geographical information systems , 1998 .

[16]  M. Voltz,et al.  Herbicide transport to surface waters at field and watershed scales in a Mediterranean vineyard area. , 2001, Journal of environmental quality.