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Bed‐material transport estimated from channel morphodynamics: Chilliwack River, British Columbia
Author(s) -
Ham Darren G.,
Church Michael
Publication year - 2000
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/1096-9837(200009)25:10<1123::aid-esp122>3.0.co;2-9
Subject(s) - beach morphodynamics , floodplain , hydrology (agriculture) , channel (broadcasting) , erosion , sediment transport , deposition (geology) , sediment , aerial photography , geology , physical geography , flood myth , vegetation (pathology) , bed load , environmental science , bedform , geomorphology , geography , archaeology , remote sensing , geotechnical engineering , cartography , medicine , engineering , pathology , electrical engineering
This study investigates the relation between channel changes, as mapped from aerial photography, and bed‐material transport along Chilliwack River, British Columbia. Detailed mapping of channel features was completed for five dates between 1952 and 1991 using an analytical stereoplotter. Data were transferred to a geographic information system (GIS) to analyse changes during four consecutive periods. Erosion and deposition volumes along channel reaches were estimated by multiplying measured areal changes by the bed‐material depth along each reach. Bed‐material transport rates are related to morphologic changes using a sediment budget approach. The highest rate of transport for the four study periods is estimated as 55 000 ± 10 000 m 3 a −1 between 1983 and 1991. These rates are compared with estimates from short‐term (1–2 year) changes along the lower reach to investigate variations in sediment flux that may otherwise remain undetected. Significant morphologic change occurs roughly once every 5 years when flows are large enough to erode and entrain large volumes of bed material stored within the contemporary floodplain. In the absence of large floods, transport rates decline and vegetation begins to establish new floodplain. Copyright © 2000 John Wiley & Sons, Ltd.