Abstract
Large river systems provide many services, including water resources,
barge transport, and sand and gravel (S&G) for mining. However, unlike
damming, the impacts of channel dredging and S&G mining are poorly
monitored. We quantify these impacts on the Lower Arkansas River,
U.S.A., where anthropogenic processes are well documented. The
construction of dams caused a 98% reduction in suspended sediment
discharge (Qss). Since dam construction,
fluvially-transported Qss and suspended sand
discharge (Qsand) varied on the decadal scale,
but the average of Qss (4.4 ± 0.5
Mtyr-1) and Qsand (1.1 ± 0.1
Mtyr-1) at Van Buren are of the same order as sediment
removal rates by dredging (1.2 ± 0.1 Mtyr-1) and S&G
mining (1.7 ± 0.1 Mtyr-1). During 1975-2019, the
cumulative sediment deficit caused by dredging and S&G mining (1.7
Mtyr-1) outpaced the cumulative post-dam fluvial
sediment deficit (0.7 Mtyr-1), indicating sediment
extractions are now essential parts of rivers’ sediment balance.