Contribution of intercepted subsurface flow to road runoff and sediment transport in a logging-disturbed tropical catchment

Abstract

Hydrological and sediment fluxes were monitored for a 1 yr period in a tropical headwater catchment where a 3 yr old logging road caused substantial Hortonian overland flow (HOF) and intercepted subsurface flow (ISSF). On a 51.5 m road section, ISSF became an increasingly important component of total road runoff, up to more than 90% for large storms. The proportion of ISSF contributed by road cuts along more or less planar slopes compared with ISSF from a zero-order basin (convergent slopes) truncated by the road declined with increasing rainfall. During the monitored storms that generated ISSF along the road, on average, 28% of sediment export and 79% of runoff from the road section were directly attributable to ISSF. Estimates of total sediment export from the road surface (170 t ha-1 yr-1) and suspended sediment export from the logging-disturbed catchment (4 t ha-1 yr-1) were exceptionally high despite 3 yr of recovery. ISSF caused not only additional road-generated sediment export, but also exacerbated HOF-driven erosion by creating a poor foundation for vegetation recovery on the road surface. Copyright © 2007 John Wiley & Sons, Ltd.