Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 21, 235-249, 2017
http://www.hydrol-earth-syst-sci.net/21/235/2017/
doi:10.5194/hess-21-235-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
11 Jan 2017
Reconstructing long-term gully dynamics in Mediterranean agricultural areas
Antonio Hayas1, Tom Vanwalleghem1, Ana Laguna2, Adolfo Peña3, and Juan V. Giráldez1,4 1University of Cordoba, Dept. of Agronomy, da Vinci Bldg., Cra Madrid km 396, 14071 Córdoba, Spain
2University of Cordoba, Dept. of Applied Physics, Einstein Bldg., Córdoba, Spain
3University of Cordoba, Dept. of Rural Engineering, da Vinci Bldg., Córdoba, Spain
4Institute for Sustainable Agriculture, CSIC, Dept. of Agronomy, Alameda del Obispo, 14080 Córdoba, Spain
Abstract. Gully erosion is an important erosive process in Mediterranean basins. However, the long-term dynamics of gully networks and the variations in sediment production in gullies are not well known. Available studies are often conducted only over a few years, while many gully networks form, grow, and change in response to environmental and land use or management changes over a long period. In order to clarify the effect of these changes, it is important to analyse the evolution of the gully network with a high temporal resolution. This study aims at analysing gully morphodynamics over a long timescale (1956–2013) in a large Mediterranean area in order to quantify gully erosion processes and their contribution to overall sediment dynamics.

A gully network of 20 km2 located in southwestern Spain has been analysed using a sequence of 10 aerial photographs in the period 1956–2013. The extension of the gully network both increased and decreased in the study period. Gully drainage density varied between 1.93 km km−2 in 1956, a minimum of 1.37 km km−2 in 1980, and a maximum of 5.40 km km−2 in 2013. The main controlling factor of gully activity appeared to be rainfall. Land use changes were found to have only a secondary effect. A new Monte Carlo-based approach was proposed to reconstruct gully erosion rates from orthophotos. Gully erosion rates were found to be relatively stable between 1956 and 2009, with a mean value of 11.2 t ha−1 yr−1. In the period 2009–2011, characterized by severe winter rainfalls, this value increased significantly to 591 t ha−1 yr−1. These results show that gully erosion rates are highly variable and that a simple interpolation between the starting and ending dates greatly underestimates gully contribution during certain years, such as, for example, between 2009 and 2011. This illustrates the importance of the methodology applied using a high temporal resolution of orthophotos.


Citation: Hayas, A., Vanwalleghem, T., Laguna, A., Peña, A., and Giráldez, J. V.: Reconstructing long-term gully dynamics in Mediterranean agricultural areas, Hydrol. Earth Syst. Sci., 21, 235-249, doi:10.5194/hess-21-235-2017, 2017.
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Short summary
Gully erosion is one of the most important erosion processes. In this study, we provide new data on gully dynamics over long timescales with an unprecedented temporal resolution. We apply a new Monte Carlo based method for calculating gully volumes based on orthophotos and, especially, for constraining uncertainties of these estimations. Our results show that gully erosion rates are highly variable from year to year and significantly higher than other erosion processes.
Gully erosion is one of the most important erosion processes. In this study, we provide new data...
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