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- Title
Suspended sediment discharge in subsurface flow from the head hollowof a small forested watershed, northern Japan
- Authors
Kitamura, Kenzo; Nakai, Yuichiro; Sakamoto, Tomoki; Terajima, Tomomi
- Abstract
Surface flow and suspended sediment discharge from the head hollow of the Jozankei Experimental Watershed in Hokkaido, northern Japan, were measured to clarify the implications of subsurface hydrology for soil movement. Subsurface discharges during the extremely large stormsof 1993 to 1994 were measured in a V-notch weir installed at a natural spring near the bottom of the head hollow, and shallow groundwaterlevels were observed in the wells excavated in the hollow. Sediment samples whose particle size range from 07001 to 071 mm were manually and automatically collected at 15 to 60 min intervals, by use of 1 or21 polyethylene bottles. Maximum concentration and flux of suspendedsediment during the storms preceded the peak discharge of subsurfaceflow by several hours. Neither the changes in concentration (mg l-1) nor flux (mg s-1) of suspended sediment coincided with those in subsurface discharge (l s-1). Furthermore, sediment concentration was poorly correlated with the rate of change in subsurface discharge (l s-2) during the rising limb of the hydrograph. Suspended sediment flux during the acceleratory limb, however, was closely correlated with the rate of change in subsurface discharge. The relationship between suspended sediment flux and rate of change in subsurface discharge were in inverse proportion to initial subsurface discharge before the storm runoff and they represented rare seasonal variation. Subsurface hydraulic erosion and transport of suspended sediment resulting from changes in rate of change insubsurface discharge actively occur during the acceleratory rising limb of the hydrograph. Accordingly, subsurface hydraulic erosion during the acceleratory rising limb of the hydrograph can be physically understood by analysing suspended sediment flux associated with rate of change in subsurface discharge and initial subsurface discharge.
- Subjects
EROSION; GROUNDWATER flow; HYDROLOGY; MATHEMATICAL analysis; STATISTICS
- Publication
Earth Surface Processes & Landforms, 1997, Vol 22, Issue 11, p987
- ISSN
0197-9337
- Publication type
Article