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Inferring sediment transfers and functional connectivity of rivers from repeat topographic surveys
Author(s) -
Calle Mikel,
Calle Javier,
Alho Petteri,
Benito Gerardo
Publication year - 2020
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.4765
Subject(s) - sediment , digital elevation model , geology , channel (broadcasting) , hydrology (agriculture) , deposition (geology) , ephemeral key , erosion , sedimentary budget , fluvial , sedimentary depositional environment , sediment transport , elevation (ballistics) , bank erosion , geomorphology , remote sensing , geotechnical engineering , engineering , algorithm , structural basin , computer science , electrical engineering , geometry , mathematics
High‐resolution topographic models have revolutionized monitoring of river changes by comparing sequential river topographic surveys (i.e. change detection). Nevertheless, much more may be obtained from this innovative quantification of changes. In this paper, we enhance the interpretation of geomorphic processes by presenting a new method for understanding of sources and sinks of sediment, river sediment transfers and functional sediment connectivity. Repeat digital elevation models (DEMs) obtained by photogrammetry were used to quantify topographic change after two floods by creating a DEM of difference (DoD) of a 6.5 km‐long reach of Rambla de la Viuda stream, an ephemeral gravel‐bed river in eastern Spain. The proposed method involved dividing the channel into 10 m‐long longitudinal strips that were used to systematically draw boundaries between the erosional and depositional areas of the DoD. The analysis objectively: (i) drew a series of erosional and depositional segments, from 120 to 1360 m in length; (ii) estimated ranges of source‐to‐storage sediment transport distances, 320–670 m in the upstream and middle reaches and up to 2030 m in the lower reach; and (iii) obtained values of functional connectivity (i.e. the ratio between the sediment exported (erosion) and retained (deposition), ranging from 10 3 to 10 −3 ). The variability in these three parameters along the river was found to be related to the level of channel disturbance by in‐stream mining during the 1990s and 2000s. Additionally, this method indicates that the main process responsible for self‐adjustment of the present morphosedimentary conditions is intra‐reach erosion of banks and channel beds. Thus, this study proposes a new methodology to characterize morphological change, sediment transfer and connectivity that may serve as environmental indicators of the hydromorphological integrity of rivers with potential application to the European Water Framework Directive. © 2019 John Wiley & Sons, Ltd.