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Universiteit van Amsterdam (2008)

Multi-scale interactions between soil, vegetation and erosion in the context of agricultural land abandonment in a semi-arid environment

Lesschen, J.P.

Titre : Multi-scale interactions between soil, vegetation and erosion in the context of agricultural land abandonment in a semi-arid environment

Auteur : Lesschen, J.P.

Université de soutenance : Universiteit van Amsterdam

Grade : Doctor 2008

Résumé partiel
The objective of this thesis was to study the interactions between soil, vegetation and erosion in the context of agricultural land abandonment at multiple scales in a semi-arid environment. The research is focused on three central themes, i.e. soil erosion, scale issues and agricultural land abandonment. Soil erosion is one of the main environmental problems in Mediterranean countries which results in soil quality loss and off-site effects such as flash flooding and reservoir sedimentation. For the mitigation of soil erosion it is important to understand the mechanisms and the critical soil conditions that are necessary for maintaining and restoring soil quality. In soil erosion research the issue of scale is very important. Different processes control erosion at the various spatial as well as temporal scales, which leads to different runoff and erosion rates. The spatial scales in this research range from plot to catchment and the temporal scales from minutes to decades. Agricultural land abandonment is one of the main changes in land use in marginal areas of northern Mediterranean countries. However, not much is known about the consequences of land abandonment in terms of land degradation. On the one hand an increase in vegetation cover can decrease erosion, but on the other hand existing soil and water conservation structures are no longer maintained, which can increase erosion. To study these three themes the Carcavo basin was selected as study area. This basin is a catchment in Southeast Spain and is representative for marginal agriculture in semi-arid environments. In Chapter 2 vulnerable areas for gully erosion were identified using different scenarios of land abandonment. A field survey showed that abandoned fields are more vulnerable to gully erosion compared to cultivated fields. An explanation is the increased runoff concentration on abandoned land due to crust formation and reduced surface storage capacity. The spatial dynamics of land abandonment were simulated with a spatially explicit land use change model for the period 2004 to 2015 for four different land use change scenarios. These results were used to identify vulnerable areas for gully erosion by a simple GIS-model based on the controlling factors of gully erosion. The potentially vulnerable areas for gully erosion increased for all scenarios ranging from 18 ha to 176 ha. The results showed that most of the vulnerable areas are located around channel heads or along channel walls. The combination of a higher gully erosion risk on abandoned fields and an expected increase of land abandonment is potentially a big problem in relation to land degradation and reservoir sedimentation. The identification of vulnerable areas enables soil conservationists and engineers to mitigate gully erosion by applying preventive conservation practices.

Mots clés : Bodemerosie ; Landgebruik ; Landbouw ; 4.630 Spanje ; erosie ; landverlating ; vegetatiepatronen ; schaal

Présentation et version intégrale

Page publiée le 6 septembre 2010, mise à jour le 2 janvier 2018