On-site effects of concentrated flow erosion in vineyard fields: some economic implications

• Published in: Catena (Giessen) 2005-02, Vol.60 (2), p.129-146
• Main Authors: Martínez-Casasnovas, José A., Ramos, M. Concepción, Ribes-Dasi, Manel
• Format: Article
• Language: English
• Subjects: Bgi / Prodig; Cost of erosion; DEMs; Ephemeral gully erosion; Filling; Pedology; Physical geography; Vineyards
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/j.catena.2004.11.006

Although it is well known that ephemeral gully erosion is a process of a recurrent nature and its contribution to total sediment production is far from negligible, there is a gap in the assessment of changes that the ephemeral gullying cycle produces in the fields' landscape and in the general economic balance of farms (the cost of erosion). The present paper applies a method for assessing the topographic changes produced by concentrated flow erosion, mainly ephemeral gullies, and their filling by farmers. The method is based on the comparison of multi-date detailed topographic data (digital elevation models, DEMs). In the case study, 0.20-m spatial resolution DEMs of March 2000, June 2000 and July 2002 were used to assess the changes in a vineyard field (located in the Penedès region, Catalonia, NE Spain), in which there are hillside ditches (broadbase terraces) that function as sediment traps to avoid major soil loss. The study period was divided into two, according to an extreme rainfall event that occurred on 10 June 2000, in which 214.6 mm fell in 1 day, representing 44% of the annual precipitation. This storm, with a return period in the area of 105 years, displaced 282±4 Mg ha −1 of sediment, 58% of which was due to concentrated surface runoff that caused considerable surface lowering (ephemeral gullies) of up to 0.4–0.5 m deep in some parts of the field. During the second period, about 208±3 Mg ha −1 of soil and sediment deposited in the hillside ditches was used to fill ephemeral gullies. The general sediment/soil balance at the locations where ephemeral gullies recurrently occur is negative (−74±3 Mg ha −1), indicating that recurrent concentrated surface runoff is producing a progressive surface lowering of those zones. The research also assessed the efficiency of the hillside ditches as sediment traps. A total of 113±2 Mg ha −1 was deposited in these structures during the period March 2000–June 2000 (in which the extreme rainfall event occurred), which represents 54% of the material used to fill ephemeral gullies in the period June 2000–July 2002. Finally, the cost of erosion, evaluated as the cost of the operations necessary to redistribute the sediment/soil over the field and to repair the hillside ditches, represented 5% of the income of the farms.