@article{4b5639bdc0d24ec29bc8c5285b8fafaa,
title = "The active layer in gravel-bed rivers: An empirical appraisal",
abstract = "The vertical position of the streambed–water boundary fluctuates during the course of sediment transport episodes, due to particle entrainment/deposition and bedform migration, amongst other hydraulic and bedload mechanisms. These vertical oscillations define a topmost stratum of the streambed (i.e. the {\textquoteleft}active layer or active depth{\textquoteright}), which usually represents the main source of particles entrained during long and high-magnitude bedload transport episodes. The vertical extent of this layer is hence a capital parameter for the quantification of bedload volumes and a major driver of stream ecology in gravel-bed rivers. However, knowledge on how the active depth scales to flow strength and the nature of the different controls on the relation between the flow strength and the active depth is still scarce. In this paper we present a meta-analysis over active depth data coming from ~130 transport episodes extracted from a series of published field studies. We also incorporate our own field data for the rivers Ebro and Muga (unpublished), both in the Iberian Peninsula. We explore the database searching for the influence of flow strength, grain size, streambed mobility and channel morphology on the vertical extent of the active layer. A multivariate statistical analysis (stepwise multiple regression) confirms that the set of selected variables explains a significant amount of variance in the compiled variables. The analysis shows a positive scaling between active depth and flow strength. We have also identified some links between the active depth and particle travel distances. However, these relations are also largely modulated by other fluvial drivers, such as the grain size of the bed surface and the dominant channel macro-bedforms, with remarkable differences between plane-bed, step-pool and riffle-pool channels.",
keywords = "active depth, active layer, bed scour, bedload, flow strength, grain size, particle entrainment, river morphology",
author = "D. V{\'a}zquez-Tarr{\'i}o and {PIQUE ALTES}, GEMMA and D. Vericat and Batalla, {R. J.}",
note = "Funding Information: The present work has been possible thanks to the financial support provided by the grant ACB17‐44, co‐funded by the postdoctoral {\textquoteleft}Clar{\'i}n Program‐FICYT{\textquoteright} (Government of the Principality of Asturias) and the Marie Curie Co‐Fund. This research was partly undertaken and benefitted from the results and discussions provided in the background of the MorphPeak (CGL2016‐78874‐R) and MorphHab (PID2019‐104979RB‐I00) projects funded by the Spanish Ministry of Economy and Competitiveness, Science and Innovation, and the European Regional Development Fund Scheme. The authors acknowledge the support of the Economy and Knowledge Department of the Catalan Government through the Consolidated Research Group {\textquoteleft}Fluvial Dynamics Research Group{\textquoteright}‐RIUS (2017SGR‐0459) and the CERCA Program. Dami{\`a} Vericat is funded through the Serra H{\'u}nter Programme (Catalan Government). We would like to thank Daniel Grace for his review of the English version of the manuscript. We finally thank the Managing Editor, the Associate Editor, and the two anonymous reviewers for their comments that substantially improved the final version of the manuscript. Funding Information: The present work has been possible thanks to the financial support provided by the grant ACB17-44, co-funded by the postdoctoral ?Clar?n Program-FICYT? (Government of the Principality of Asturias) and the Marie Curie Co-Fund. This research was partly undertaken and benefitted from the results and discussions provided in the background of the MorphPeak (CGL2016-78874-R) and MorphHab (PID2019-104979RB-I00) projects funded by the Spanish Ministry of Economy and Competitiveness, Science and Innovation, and the European Regional Development Fund Scheme. The authors acknowledge the support of the Economy and Knowledge Department of the Catalan Government through the Consolidated Research Group ?Fluvial Dynamics Research Group?-RIUS (2017SGR-0459) and the CERCA Program. Dami? Vericat is funded through the Serra H?nter Programme (Catalan Government). We would like to thank Daniel Grace for his review of the English version of the manuscript. We finally thank the Managing Editor, the Associate Editor, and the two anonymous reviewers for their comments that substantially improved the final version of the manuscript. Publisher Copyright: {\textcopyright} 2020 John Wiley & Sons, Ltd. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.",
year = "2021",
month = feb,
doi = "10.1002/esp.5027",
language = "English",
volume = "46",
pages = "323--343",
journal = "Earth Surface Processes and Landforms",
issn = "0197-9337",
number = "2",
}