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Structural and functional connectivity as a driver of hillslope erosion following disturbance.
Williams, C.J., Pierson, F.B., Robichaud, P.R., Al-Hamdan, O.Z., Boll, J., and Strand, E.K. 2016
Structural and functional connectivity as a driver of hillslope erosion following disturbance.
International Journal of Wildland Fire 25(3), 306–321.
http://dx.doi.org/10.1071/WF14114
Keywords: ecohydrology, fire effects, infiltration, risk assessment, runoff, soil erosion, vegetation transition,
wildfire, woodland encroachment
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Abstract:
Hydrologic response to rainfall on fragmented or burnt hillslopes is strongly influenced by the ensuing
connectivity of runoff and erosion processes. Yet cross-scale process connectivity is seldom evaluated in field studies
owing to scale limitations in experimental design. This study quantified surface susceptibility and hydrologic response
across point to hillslope scales at two degraded unburnt and burnt woodland sites using rainfall simulation and hydrologic
modelling. High runoff (31–47 mm) and erosion (154–1893 g m 2) measured at the patch scale (13 m2) were associated
with accumulation of fine-scale (0.5-m2) splash-sheet runoff and sediment and concentrated flow formation through
contiguous bare zones (64–85% bare ground). Burning increased the continuity of runoff and sediment availability and
yield. Cumulative runoff was consistent across plot scales whereas erosion increased with increasing plot area due to
enhanced sediment detachment and transport. Modelled hillslope-scale runoff and erosion reflected measured patch-scale
trends and the connectivity of processes and sediment availability. The cross-scale experiments and model predictions
indicate the magnitude of hillslope response is governed by rainfall input and connectivity of surface susceptibility,
sediment availability, and runoff and erosion processes. The results demonstrate the importance in considering cross-scale
structural and functional connectivity when forecasting hydrologic and erosion responses to disturbances.
Moscow FSL publication no. 2016e
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