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Fluvial system dynamics derived from distributed sediment budgets: perspectives from an uncertainty-bounded application

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The utility of sediment budget analysis is explored in revealing spatio-temporal changes in the sediment dynamics and morphological responses of a fluvial system subject to significant human impacts during the recent Anthropocene. Sediment budgets require a data-intensive approach to represent spatially-differentiated impacts adequately and are subject to numerous estimation uncertainties. Here, field and topographic surveys, historical data, numerical modelling and a representative-area extrapolation method are integrated to construct a distributed, process-based sediment budget that addresses historical legacy factors for the highly regulated Lagunitas Creek (213 km2), California, USA, for the period 1983–2008. Independent corroboration methods and error propagation analysis produce an uncertainty assessment unique to a catchment of this size. Current sediment yields of ~20,000 t a-1 ± 6,000 t a-1 equate to unit rates of ~300 t km-2 a-1 ± 90 t km-2 a-1 over the effective sediment contributing area of 64 km2. This is comparable to yields associated with early Euro-American settlement in the catchment, despite loss of sediment supply upstream of the two large dams. It occurs because ~57% of the sediment is now derived from incision-related channel erosion. Further, the highly efficient routing of channel-derived sediments in these incised channels suggests an efflux of 84% of contemporary sediment production, contrasting with the efflux of ≈10–30% reported for unregulated agricultural catchments. The results highlight that sediment budgets for regulated rivers must accommodate channel morphological responses to avoid significantly misrepresenting catchment yields, and that volumetric precision in sediment budgets may best be improved by repeat, spatially dense, channel cross-section surveys. Human activities have impacted every aspect of the sediment dynamics of Lagunitas Creek (production, storage, transfer, rates of movement through storage), confirming that, while distributed sediment budgets are data demanding and subject to numerous error sources, the approach can provide valuable insights into Anthropocene fluvial geomorphology.
Original languageEnglish
Pages (from-to)1335-1354
Number of pages20
JournalEarth Surface Processes and Landforms
Issue number6
Early online date16 Dec 2017
Publication statusPublished - 1 May 2018


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    Rights statement: This is the peer reviewed version of the following article: Downs, P. W., Dusterhoff, S. R., Leverich, G. T., Soar, P. J., and Napolitano, M. B. (2017) Fluvial system dynamics derived from distributed sediment budgets: perspectives from an uncertainty-bounded application. Earth Surf. Process. Landforms, doi: 10.1002/esp.4319, which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

    Accepted author manuscript (Post-print), 1.49 MB, PDF document

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