HR: 13:45h
AN: B32C-01 INVITED     [PDF]
TI: Effects of Forest Disturbance on Chronic and Episodic Hydrogeomorphic Processes
AU: * Sidle, R C
EM: sidle@slope.dpri.kyoto-u.ac.jp
AF: Kyoto University, DPRI, Gokasho, Kyoto-fu, Uji-shi, 611-0011 Japan
AB: Dominant hydrogeomorphic processes in forest environments differ in relation to climate and biogeography, but also with respect to location within drainage basins. For example, in steep headwaters, episodic geomorphic processes (e.g., landslides, debris flows) are typically the major supplier of sediment to streams, and sediment and woody debris are routed through steep channels by a combination of mass wasting and episodic fluvial processes. Tributary junctions play a key role in storing and releasing materials. In gentler reaches further downstream, such sediment and wood are typically supplied and transported by chronic processes such as surface wash, litter and tree fall, and bedload and suspended sediment transport. Additionally, subsurface flow processes often dominate in upper catchment reaches while saturated overland flow controls much of the storm runoff in lower reaches where riparian corridors are wide. Subsurface and surface hydrologic pathways are strongly affected by antecedent moisture, especially in steep headwaters. Thus, effects forest land uses, such as roads and trails, harvesting, and conversion to agriculture, exert different influences depending on when and where they occur within the catchment. Hydrogeomorphic responses to forest management in steep terrain are compared between temperate catchments, where sediment is supplied largely by landslides, and tropical catchments, where organic horizons are thin and surface erosion follows disturbance. Management effects on chronic versus episodic hydrogeomorphic processes are stressed, including feedback between these processes.
DE: 1803 Anthropogenic effects
DE: 1815 Erosion and sedimentation
DE: 1860 Runoff and streamflow
SC: Biogeosciences [B]
MN: 2003 Fall Meeting