HR: 11:35h
AN: H51F-06    [PDF]
TI: Bedload transport in a tropical headwater catchment
AU: * Ziegler, A D
EM: ADZ@HAWAII.EDU
AF: GEOGRAPHY | NATIONAL UNIVERSITY SINGAPORE, 1 ARTS LINK | KENT RIDGE, SINGAPORE, 656777 Singapore
AU: * Ziegler, A D
EM: ADZ@HAWAII.EDU
AF: GEOGRAPHY | UNIVERSITY OF HAWAII, 2424 MAILE WAY 445 SSB, HONOLULU, HI 96822 United States
AU: Giambelluca, T W
EM: THOMAS@HAWAII.EDU
AF: GEOGRAPHY | UNIVERSITY OF HAWAII, 2424 MAILE WAY 445 SSB, HONOLULU, HI 96822 United States
AU: Sutherland, R A
EM: SUTHERLA@HAWAII.EDU
AF: GEOGRAPHY | UNIVERSITY OF HAWAII, 2424 MAILE WAY 445 SSB, HONOLULU, HI 96822 United States
AU: Nullet, M A
EM: MNULLET@HAWAII.EDU
AF: GEOGRAPHY | UNIVERSITY OF HAWAII, 2424 MAILE WAY 445 SSB, HONOLULU, HI 96822 United States
AB: Multi-year observations reveal a distinct seasonal pattern in the transport of bedload material in stream draining a 94-ha headwater basin in northern Thailand. The patterning is related to the presence of a monsoon rainy season, during which 90% of the annual 1200-1400 mm of rainfall occurs. Mean daily bedload transport during the wet season (mid-May through October) is 3-4 times greater than that during the drier months. More than 70% of the annual bedload total is mobilized during the wet season. A clock-wise hysteresis pattern characterizes the annual time series, such that more material is mobilized per unit discharge during the wet months than the drier months. This phenomenon results, in part, from two processes related to the monsoon climate regime and the current land-use: (a) large volumes of bedload are transported during a handful of short, flashy runoff events; and (b) bedload material is continually re-supplied during the wet period by runoff entering the stream from the road network. Also apparent in the annual transport pattern is a coarsening of bedload transported during the wettest months, when mean daily stream flow is 4-5 greater higher than that during the drier months. The size of material transported during storm events appears to be limited by the bed architecture (e.g., imbrication) up to a threshold discharge of about 2/3 bank full discharge (QBF = 0.5 cms). In five years of monitoring, QBF has been exceeded only once. The largest stone transported during that event was 10.65 kg; the diameter of the b-axis was 0.21 m.
DE: 1815 Erosion and sedimentation
DE: 1860 Runoff and streamflow
DE: 9320 Asia
SC: Hydrology [H]
MN: 2003 Fall Meeting