Updated knowledge about concentrated flow erosion in Navarre (Spain)

J. Casalí, R. Giménez, L. de Santisteban, M. A. Campo, J. Álvarez Mozos, M. Goñi, R. Gastesi

Abstract


There are few studies at a European level on concentrated flow erosion, especially with regard to gullies. In Spain, in particular, this information is still more limited. In this work, we have made a brief review of the current state of the knowledge on erosion in concentrated flows available in Navarre. For this purpose, the main results and conclusions of experimental studies carried out in different areas of the Navarre region in mini-basins and basins are presented. To locate the different experimental sites analysed, a pre-existent zone division of the territory, according to its erosive ambients, was used. In the central zone of Navarre and on a small scale, up to one hectare, the type of crop predominating (cereal and vines) seems to be a leading factor in erosion processes. So much so that the average erosion intensity per gullies and rills in vines is of around 2.5 kg m-2 year-1, that is, over double the most permissive values of soil loss tolerance. There are similarly important soil losses in cereals, especially from gullies, although the average loss values are below the tolerance threshold. In studies made on a larger scale, the complex topography and relief of the territory become highly significant factors in the control of these processes. For instance, two cerealist basins, apparently similar to each other, nevertheless show notable differences in sediment exportation: in one, the average annual production is of 1,800 kg ha-1 year-1, whereas in the other it is only 300 kg ha-1 year-1. In forested basins, however, the values are normally lower than those recorded in cerealist basins but they can sometimes exceed them, depending on the forest management carried out. The greatest erosion intensity is recorded during the winter since this is when, generally, the soils are almost bare and humid. Both the central and southern regions of Navarre are affected, sometimes seriously, by erosion in permanent gullies. To be specific, within Bardenas Reales de Navarra, the average intensity of the permanent gully head advance takes on values, depending on its different origin and typology, of between 3,000 to 94,000 kg ha-1 year-1. This paper also includes an extensive and critical review of the current definitions of the main phenomena involved in concentrated flow erosion.



DOI: http://dx.doi.org/10.18172/cig.1213

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© Universidad de La Rioja, 2013

ISSN 0211-6820

EISSN 1697-9540