Vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain area
Version of Record online: 20 JAN 2009
Copyright © 2009 John Wiley & Sons, Ltd.
Earth Surface Processes and Landforms
Volume 34, Issue 6, pages 755–767, May 2009
How to Cite
Molina, A., Govers, G., Cisneros, F. and Vanacker, V. (2009), Vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain area. Earth Surf. Process. Landforms, 34: 755–767. doi: 10.1002/esp.1747
- Issue online: 23 APR 2009
- Version of Record online: 20 JAN 2009
- Manuscript Accepted: 21 JUL 2008
- Manuscript Revised: 7 JUL 2008
- Manuscript Received: 9 MAY 2007
- sediment trapping;
- sediment budget;
Active gully systems developed on highly weathered or loose parent material are an important source of runoff and sediment production in degraded areas. However, a decrease of land pressure may lead to a return of a partial vegetation cover, whereby gully beds are preferred recolonization spots. Although the current knowledge on the role of vegetation on reducing sediment production on slopes is well developed, few studies exist on the significance of restoring sediment transport pathways on the total sediment budget of degraded mountainous catchments. This study in the Ecuadorian Andes evaluates the potential of vegetation to stabilize active gully systems by trapping and retaining eroded sediment in the gully bed, and analyses the significance of vegetation restoration in the gully bed in reducing sediment export from degraded catchments. Field measurements on 138 gully segments located in 13 ephemeral steep gullies with different ground vegetation cover indicate that gully bed vegetation is the most important factor in promoting short-term (1–15 years) sediment deposition and gully stabilization. In well-vegetated gully systems ( ≥ 30% of ground vegetation cover), 0.035 m3 m–1 of sediment is deposited yearly in the gully bed. Almost 50 per cent of the observed variance in sediment deposition volumes can be explained by the mean ground vegetation cover of the gully bed. The presence of vegetation in gully beds gives rise to the formation of vegetated buffer zones, which enhance short-term sediment trapping even in active gully systems in mountainous environments. Vegetation buffer zones are shown to modify the connectivity of sediment fluxes, as they reduce the transport efficiency of gully systems. First calculations on data on sediment deposition patterns in our study area show that gully bed deposition in response to gully bed revegetation can represent more than 25 per cent of the volume of sediment generated within the catchment. Our findings indicate that relatively small changes in landscape connectivity have the potential to create strong (positive) feedback loops between erosion and vegetation dynamics. Copyright © 2009 John Wiley & Sons, Ltd.