HR: 11:35h
AN: H42B-06    [Abstracts]
TI: Runoff Generation and Wash Sediment Transport in Semi-arid and Humid Landscapes
AU: * Kirkby, M J
EM: m.j.kirkby@leeds.ac.uk
AF: School of Geography, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT United Kingdom
AB: Although partial area concepts may be widely applicable, the increase in overland flow discharge with slope length and gradient depends strongly on the runoff generating mechanisms - infiltration or saturation excess - and seasonal or event-driven switching between them. The same power law relationship between discharge and sediment transport can lead to very different exponents for the topographic factors of slope length and gradient. Infiltration excess gives less than linear increases of discharge with distance and strong increases with gradient. Slope forms therefore show narrow convexity and long weak concavities. Saturation excess gives initially little runoff and then a strong increase with distance, with a partly inverse relationship with gradient, giving broad convexities and a sharp, narrow basal concavity. Sub-surface flow also promotes mass movements and solutional denudation, with further impacts on and interactions with landscape morphology. Switching between runoff generation styles may be seasonal, though commonly showing considerable variation from year to year, or may reflect the event history, tending towards infiltration excess for larger events and vice-versa. Evolution models should, in principle, integrate over both event sizes and runoff styles to respond properly to the hydrology in each particular landscape context.
DE: 1807 Climate impacts
DE: 1815 Erosion
DE: 1817 Extreme events
DE: 1826 Geomorphology: hillslope (1625)
DE: 1866 Soil moisture
SC: Hydrology [H]
MN: Fall Meeting 2005