Geochemical Fingerprinting - Application of Geochemical Tracers to Fluvial Sediment - page 34

Fig. 2.7 a Estimated relative source contributions to suspended sediment sampled during a flood
event in 1998 within the upper Kaleya Catchment. Note intra-flood variability in sediment prove-
nance. b Load-weighted sediment source contributions for runoff events sampled in 1998 and 1999
( left ), and calculated for the entire wet periods between 1997 and 1999 ( right ) within the upper
Kaleya Catchment (adapted from Collins et al. 2001 )
samples are sensitive to the timing of sample collection, (2) the need to collect
samples during flood events; (3) the need to collect and process significant volumes
of water to obtain enough sediment for geochemical analysis, and (4) the costs and
time required for processing a large number of samples to adequately characterize
contributions during a protracted time period (e.g., season or year). More recent
studies have focused on sediment collected using passive sediment traps/samplers,
channel bed sediments, or sediments located at the surface of floodplains.
Collins et al. ( 2010a ), for example, applied geochemical fingerprinting to river
sediments obtained from the floodplain surface near the mouth of seven subcatch-
ments of the Somerset Levels in the UK (Fig. 2.8 ). These samples were assumed to
represent sediments eroded during moderate floods that transported the majority of
the sediment in the basins. The study area is part of the England Catchment Sen-
sitive Farming Delivery Initiative where Catchment Sensitive Farming Officers are