{"id":242,"date":"2018-04-24T08:35:33","date_gmt":"2018-04-24T06:35:33","guid":{"rendered":"http:\/\/wp.unil.ch\/alpenv\/?page_id=242"},"modified":"2018-04-24T08:46:38","modified_gmt":"2018-04-24T06:46:38","slug":"sedfate","status":"publish","type":"page","link":"https:\/\/wp.unil.ch\/alpenv\/home\/our-projects\/sedfate\/","title":{"rendered":"Sediment fate in a changing watershed during the Anthropocene (SEDFATE)"},"content":{"rendered":"

UNIL staff: Maarten Bakker<\/a>, Stuart Lane<\/a><\/strong><\/p>\n

SEDFATE was a 4 year project (2014-2018) that quantified changes in sediment flux in the Swiss Rh\u00f4ne basin, in the central European Alps, during the late Anthropocene to answer<\/p>\n

    \n
  1. what are the precise timings, amplitudes and patterns of change in sediment flux, if any?;<\/li>\n
  2. where are the sources responsible for the change?; and<\/li>\n
  3. what are the mechanisms responsible for change, including the role of human activities in this context?<\/li>\n<\/ol>\n

    These questions were addressed through four subprojects, involving a collaboration between the Universities of Geneva, Lausanne and Berne and the ETH at Z\u00fcrich:<\/p>\n

    A<\/em><\/strong> (lead, UniGE) focused on the quantification of the pattern of sediment flux to Lake Geneva within a detailed chronological framework for the past ca. 100 years;<\/p>\n

    B<\/em><\/strong> (lead, UniBE) identified the relative sources of sediment in selected sub-basins of the Rh\u00f4ne River using dating and provenance tracing techniques;<\/p>\n

    C<\/em><\/strong> (lead, UniLA) assessed the effects of primary (water abstraction, sluicing and flushing) and secondary (climate change) human impacts on the sediment production, sorting and redistribution downstream in the system; and<\/p>\n

    D<\/em><\/strong> (lead, ETHZ) applied a physically-based basin-scale model to upscale work C<\/em><\/strong> to consider flow regulation and sediment flux in the entire Rh\u00f4ne basin and its main river course.<\/p>\n

    There were 4 key findings<\/p>\n

    First,\u00a0<\/strong>On the basis of carefully-designed sampling of sediment cores, higher rates of sediment supply to Lake Geneva (D<\/strong>) and rapid sedimentation rates in Lake Geneva (A<\/strong>) correlate with climatically warmer periods suggesting that, and contrary to what was expected, even in a very heavily modified river basin climate change signals may propagate through to the depositional record.<\/p>\n

    Second<\/strong>, this climate signal relates predominantly to the effects of climate warming on the release of sub-glacially stored material, confirmed through sediment fingerprinting (<\/span>B<\/strong>), analysis of hydropower company records combined with reach-scale hydraulic modelling (<\/span>C<\/strong>) and by basin scale statistical modelling (<\/span>D<\/strong>) (e.g. Figure 1).\u00a0<\/span><\/p>\n

    \"\"<\/p>\n

    Figure 1. Changes in suspended sediment concentration close to the mouth of the Swiss Rh\u00f4ne showing a statistically significant increase in sediment concentration since the mid 1980s, but primarily in summer<\/em> months. Further research showed that this was due to greater rates of ice melt during a period of rapid climate warming (Costa et al., 2018<\/a>).<\/p>\n

    Third<\/strong>, human impacts, notably associated with hydropower do not necessarily disconnect sediment flux from source areas to downstream (C<\/strong>) but they may increase the sensitivity of sediment flux to climate variability and climate warming, but also to slight changes in how hydropower is managed (C<\/strong>, Figure 2), with consequences that can be detected in sediment provenance (B<\/strong>), measured sediment flux (D<\/strong>) and the size of fine sediment deposited in Lake Geneva with increase in size over the last 20 years attributed to the changing water management regime (A<\/strong>). These conclusions appear to hold more strongly for sediment transported in suspension than they do for bed sediment transport (D<\/strong>).<\/p>\n

    \"\"<\/p>\n

    Figure 2. Volumes of sediment flux through an upstream series of reaches, A through D, reconstructed from archival digital photogrammetry and intake operation data (Bakker et al., 2018<\/a>). Reach A has become a net sediment sink due to water abstraction for hydropower (that maintains sediment flux) but there is still substantial downstream flux of sediment (sediment transfer does not return to zero).<\/p>\n

    Fourth<\/strong>, in addition to these substantive scientific findings, the project made a number of important but more specific methodological developments, including: questioning the use of Be for estimation of denudation rates associated with glacial erosion (B<\/strong>); the development of a new provenance proxy (B<\/strong>); archival image analysis for reconstructing long-term sediment budgets (C<\/strong> Figure 3); influence of spatial patterns of bedload transport using application of the two-dimensional form of the Exner equation (C<\/strong>); new rating curve and conceptual models for predicting fine and coarse sediment flux through large and complex basins under both climate and human forcing (D<\/strong>).<\/p>\n

    \"\"<\/p>\n

    Figure 3. Erosion and deposition in the Borgne d\u2019Arolla between 1959 (before the onset of hydropower activities) and 2014, reconstructed using archival digital photogrammetry (Bakker and Lane, 2017<\/a>)<\/p>\n

    Published project results from the entire\u00a0SEDATE project <\/strong>(copies can be provided upon request to stuart.lane@unil.ch)<\/strong><\/p>\n

    Antoniazza, G., Bakker, M. and Lane, S.N., in review. Revisiting the morphological method in two-dimensions to quantify bed material transport in braided rivers. Submitted to Earth Surface Processes and Landforms<\/em>.<\/p>\n

    Bakker, M. Costa, A., Silva, T. A. Stutenbecker, L., Girarclos, S., Loizeau, J.-L., Molnar, P., Schlunegger, F. and Lane, S. N., 2018. Combined flow abstraction and climate change impacts on an aggrading Alpine river. Water Resources Research<\/em>, 54, 223\u2013242<\/a>.<\/p>\n

    Bakker, M. and Lane, S.N., 2017. Archival photogrammetric analysis of river-floodplain systems using Structure from Motion (SfM) methods. Earth Surface Processes and Landforms<\/em>, 42, 1274\u20131286<\/a>.<\/p>\n

    Costa A., Molnar P., Schmitt R.J.P., Burlando,P., (in review) Flow Regulation in Alpine Rivers: a Network-Based Model to Investigate the Impacts on Bedload and Grain Size Distribution, Water Resources Research<\/p>\n

    Costa A., Anghileri D., Molnar P. (2018b) Hydroclimatic control on suspended sediment dynamics of a regulated Alpine catchment: a conceptual approach, HESS Discussion, doi.org\/10.5194\/hess-2018-5<\/a>.<\/p>\n

    Costa A., Molnar P., Stutenbecker L., Bakker M., Silva T. A., Schlunegger F., Lane S. N., Loizeau J.- L., and Girardclos S. (2018a), Temperature signal in suspended sediment export from an Alpine catchment, Hydrol. Earth Syst. Sci., 22, 509-528<\/a><\/p>\n

    Lane, S.N., Bakker, M., Gabbud, C., Micheletti, N. and Saugy, J-N, 2017. Sediment export, transient landscape response and catchment-scale connectivity following rapid climate warming and Alpine glacier recession. Geomorphology<\/em>, 277, 210-27<\/a><\/p>\n

    Silva, T.A., Girardclos, S., Stutenbecker, L, Bakker, M., Costa, A., Schlunegger, F., Lane, S.N., Molnar, P., and Loizeau, J.-L., (in review) The sediment budget and dynamics of a delta-canyon-lobe system over the Anthropocene timescale: the Rh\u00f4ne River delta, lake Geneva, Sedimentology.<\/p>\n

    Stutenbecker, L., Costa, A., Schlunegger, F. (2016) Lithological control on the landscape form of the upper Rh\u00f4ne basin, Central Swiss Alps. Earth Surf. Dynam., 4, 253-272<\/a>.<\/p>\n

    Stutenbecker, L., Berger, A., and Schlunegger, F., (2017) The potential of detrital garnet as a provenance proxy in the Central Swiss Alps. Sediment. Geol., 351, 11-20<\/a>.<\/p>\n

    Stutenbecker, L., Delunel, R., Silva, T.A., Schlunegger, F., \u0160egvi?, B, Loizeau, J.-L., Bakker, M., Costa, A., Lane, S.N., Girardclos, S., Molnar, P., Ak\u00e7ar, N., Christl, M (2018). Reduced sediment supply in a fast eroding landscape? A multi-proxy sediment budget of the upper Rh\u00f4ne basin, Central Alps. Sediment. Geol., in press<\/a>.<\/p>\n

    Stutenbecker, L., Costa, A., Bakker, M., Anghileri, D., Molnar, P., Lane, S.,N and Schlunegger, F., (submitted). Disentangling the influence of human impact from natural controls of the sediment dynamics of an Alpine catchment. In review at Earth Surface Processes and Landforms<\/em><\/p>\n

     <\/p>\n

     <\/p>\n","protected":false},"excerpt":{"rendered":"

    UNIL staff: Maarten Bakker, Stuart Lane SEDFATE was a 4 year project (2014-2018) that quantified changes in sediment flux in the Swiss Rh\u00f4ne basin, in the central European Alps, during the late Anthropocene to answer what are the precise timings,<\/p>\n","protected":false},"author":1001734,"featured_media":0,"parent":107,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"class_list":["post-242","page","type-page","status-publish"],"_links":{"self":[{"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/pages\/242","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/users\/1001734"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/comments?post=242"}],"version-history":[{"count":0,"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/pages\/242\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/pages\/107"}],"wp:attachment":[{"href":"https:\/\/wp.unil.ch\/alpenv\/wp-json\/wp\/v2\/media?parent=242"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}