Application of a confluence-based sediment-fingerprinting approach to a dynamic sedimentary catchment, New Zealand

Abstract

Fine sediment is a dynamic component of the fluvial system, contributing to the physical form, chemistry and ecological health of a river. It is important to understand rates and patterns of sediment delivery, transport and deposition. Sediment fingerprinting is a means of directly determining sediment sources via their geochemical properties, but it faces challenges in discriminating sources within larger catchments. In this research, sediment fingerprinting was applied to major river confluences in the Manawatu catchment as a broad‐scale application to characterizing sub‐catchment sediment contributions for a sedimentary catchment dominated by agriculture. Stepwise discriminant function analysis and principal component analysis of bulk geochemical concentrations and geochemical indicators were used to investigate sub‐catchment geochemical signatures. Each confluence displayed a unique array of geochemical variables suited for discrimination. Geochemical variation in upstream sediment samples was likely a result of the varying geological source compositions. The Tiraumea sub‐catchment provided the dominant signature at the major confluence with the Upper Manawatu and Mangatainoka sub‐catchments. Subsequent downstream confluences are dominated by the upstream geochemical signatures from the main stem of Manawatu River. Variability in the downstream geochemical signature is likely due to incomplete mixing caused in part by channel configuration. Results from this exploratory investigation indicate that numerous geochemical elements have the ability to differentiate fine sediment sources using a broad‐scale confluence‐based approach and suggest there is enough geochemical variation throughout a large sedimentary catchment for a full sediment fingerprint model. Combining powerful statistical procedures with other geochemical analyses is critical to understanding the processes or spatial patterns responsible for sediment signature variation within this type of catchment. Copyright © 2015 John Wiley & Sons, Ltd.

Seeking the Shore: Evidence for Active Submarine Canyon Head Incision Due to Coarse Sediment Supply and Focusing of Wave Energy

“…A wood fragment in the uppermost turbidite in core VC-157 yielded a > modern 14 C date (supporting information Table S1), suggesting recent deposition. supporting information Table S2), useful for sediment fingerprinting (e.g., Vale et al, 2016). Sediment compositions are compared using principal component analysis, which transforms multiple correlated variables into a smaller number of uncorrelated variables, or principal components (Figure 3b; cf.…”

“…Sediment compositions are compared using principal component analysis, which transforms multiple correlated variables into a smaller number of uncorrelated variables, or principal components (Figure 3b; cf. supporting information Table S2), useful for sediment fingerprinting (e.g., Vale et al, 2016). Core VC-155 was measured at 5-cm increments using pXRF, and subsamples of the two sand intervals were sieved and washed in deionized water prior to analysis to remove interstitial mud, which represents less than 10% of the sand intervals, but coats larger particles.…”

Community managed forests dominate the catchment sediment cascade in the mid-hills of Nepal: A compound-specific stable isotope analysis

“…Sediment fingerprinting has been successfully applied as a tool to gain insights into sediment dynamics at a river basin scale in catchments all over the world since the 1970s (Mukundan et al, 2012;Walling, 2013). Spatio-temporal variation of sediment source apportionment has received increasing attention (Cooper et al, 2015;Vale et al, 2016;Vercruysse et al, 2017), because primary sediment sources are site-specific and vary within a catchment (Koiter et al, 2013a;Stewart et al, 2015). In essence, changes in rainfall pattern and intensity, and land cover change in both natural (e.g.…”

“…Often the fingerprinting signature of different land uses (sources) is only weakly expressed by the applied tracer techniques (Pulley et al, 2017). A possible solution lies in alternative sampling approaches, such as (1) 'compositional evolution' (Hardy et al, 2010), whereby sources, as well as sediment, are sampled along the river, or (2) 'confluence-based sediment fingerprinting' (Vale et al, 2016), whereby upstream sediment samples are taken as a proxy 6 for sub-catchment sediment signature in order to evaluate relative source contributions for larger catchments. The former approach does not account accurately for sub-catchment contributions as well as local variability of tracers, while the latter approach lacks the ability to provide information on the specific sediment sources within sub-catchments (Vale et al, 2016).…”

Interpreting nested storm event suspended sediment‐discharge hysteresis relationships at large catchment scales

“…The Manawatū River drains a 5,850‐km 2 catchment in the lower North Island of New Zealand with a gauging station representing 3,903 km 2 of the catchment (Figure ). The river drains both the western and eastern slopes of the southern Ruahine and northern Tararua mountain ranges and hill country on the eastern boundary (Vale, Fuller, Procter, Basher, & Smith, , ). The river has the unusual property of flowing from the eastern catchments westward back through the mountain ranges it drains before crossing the Manawatū plains to the sea on the west coast (Figure ).…”