Root properties of vegetation communities and their impact on the erosion resistance of river dikes
Vannoppen, W.; Poesen, J.; Peeters, P.; De Baets, S.; Vandevoorde, B. (2016). Root properties of vegetation communities and their impact on the erosion resistance of river dikes. Earth Surf. Process. Landforms 41(14): 2038-2046. https://dx.doi.org/10.1002/esp.3970
In: Earth Surface Processes and Landforms: the Journal of the British Geomorphological Research Group. John Wiley/Wiley: Chichester, Sussex; New York. ISSN 0197-9337; e-ISSN 1096-9837
Predicted climate change and the associated sea level rise poses an increased threat of flooding due to wave overtopping events at sea and river dikes. To safeguard the land from flooding it is important to keep the soil erosion resistance at the dikes high. As plant roots can be very effective in reducing soil erosion rates by concentrated flow, the main goal of this study is to explore the variability in root system characteristics of five dike vegetation communities along the Scheldt River (Belgium) and to assess their effectiveness in controlling soil erosion rates during concentrated flow. This study is the first one to investigate systematically the erosion-reducing potential of the root properties of representative dike vegetation communities in a temperate humid climate.
Results show that the presence of U. dioica resulted in large differences in root length density (RLD) among dike vegetation communities. Observed RLD values in the topsoil ranged from 129 to 235?km?m-3 for dike vegetation communities without U. dioica, while smaller values ranging from 22 to 58?km?m-3 were found for vegetation communities with U. dioica. The erosion-reducing effect of the dike vegetation communities was estimated based on a global Hill curve model, linking the root length density to the soil detachment ratio (SDR; i.e. the ratio of the soil detachment rate for root-permeated topsoils to the soil detachment rate for root-free topsoils). Concentrated flow erosion rates are likely to be reduced to 13 – 16% of the erosion rates for root-free topsoils if U. dioica is present compared to 22 – 30% for vegetation communities without U. dioica. Hence, to maintain a high resistance of the soil against concentrated flow erosion it is important to avoid the overgrowth of grassland by U. dioica through an effective vegetation management.
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