Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Source of suspended-sediment within a tropical catchment recovering from selective logging.
AU - Chappell, Nick A.
AU - Douglas, Ian
AU - Hanapi, Jamal Mohd
AU - Tych, Wlodek
N1 - The dataset of high-frequency sediment flux from rainforest micro-catchments analysed here is unique within the tropics. It is leading to revision of the assessment of commercial logging impacts on erosion and landsliding. The idea was Chappell's; the external collaborators helped with data collection. RAE_import_type : Journal article RAE_uoa_type : Earth Systems and Environmental Sciences
PY - 2004/3
Y1 - 2004/3
N2 - Quantification of the source of suspended sediments generated by selective forestry activities is central to the development of sustainable forestry guidelines. This assessment is hampered by a dearth of available studies, particularly from the tropics. This study involved the monitoring (at 10 s intervals) of surface discharge and turbidity from 15 contributory areas of a 44 ha catchment. The catchment is located within lowland dipterocarp rain forest on Borneo Island, in a region recovering from the first episode of selective timber removal that took place some 5 years previously. Both the within-storm dynamics of the sediment flux and the time-integrated sediment yields were analysed to link the source landforms to the catchment behaviour. A 10 year rainfall event of 167 mm occurred during the monitoring period and triggered a debris slide and several log-culvert collapses along the area's main timber haulage road. The sampling design captured this event's dynamics and allowed lumped catchment response to be traced to the new landforms. During the 1 day period of the 10 year event, some 33 t of suspended sediment were transported from one debris slide, comprising a significant proportion of the 105 t discharging from the whole catchment, which itself constituted 40% of the annual yield of 592 t km-2. The contributory areas with only ephemeral waterflows, including former haulage roads and tracks, generated relatively little sediment during this 10 year event or in other storms. This work suggests that though some sediment sources recover from the impacts of forest road construction and harvesting, collapse of roadfill materials or more local log-culvert failure persists for several years after harvesting. Sustainable forestry guidelines that do not focus on ameliorating these persistent instabilities may not significantly mitigate the geomorphic impacts of conventional, selective harvesting. Copyright © 2004 John Wiley & Sons, Ltd.
AB - Quantification of the source of suspended sediments generated by selective forestry activities is central to the development of sustainable forestry guidelines. This assessment is hampered by a dearth of available studies, particularly from the tropics. This study involved the monitoring (at 10 s intervals) of surface discharge and turbidity from 15 contributory areas of a 44 ha catchment. The catchment is located within lowland dipterocarp rain forest on Borneo Island, in a region recovering from the first episode of selective timber removal that took place some 5 years previously. Both the within-storm dynamics of the sediment flux and the time-integrated sediment yields were analysed to link the source landforms to the catchment behaviour. A 10 year rainfall event of 167 mm occurred during the monitoring period and triggered a debris slide and several log-culvert collapses along the area's main timber haulage road. The sampling design captured this event's dynamics and allowed lumped catchment response to be traced to the new landforms. During the 1 day period of the 10 year event, some 33 t of suspended sediment were transported from one debris slide, comprising a significant proportion of the 105 t discharging from the whole catchment, which itself constituted 40% of the annual yield of 592 t km-2. The contributory areas with only ephemeral waterflows, including former haulage roads and tracks, generated relatively little sediment during this 10 year event or in other storms. This work suggests that though some sediment sources recover from the impacts of forest road construction and harvesting, collapse of roadfill materials or more local log-culvert failure persists for several years after harvesting. Sustainable forestry guidelines that do not focus on ameliorating these persistent instabilities may not significantly mitigate the geomorphic impacts of conventional, selective harvesting. Copyright © 2004 John Wiley & Sons, Ltd.
KW - erosion • forest roads • Malaysia • sediment budget • sediment delivery • turbidity
U2 - 10.1002/hyp.1263
DO - 10.1002/hyp.1263
M3 - Journal article
VL - 18
SP - 685
EP - 701
JO - Hydrological Processes
JF - Hydrological Processes
SN - 0885-6087
IS - 4
ER -