Service interruption on Monday 11 July from 12:30 to 13:00: all the sites of the CCSD (HAL, EpiSciences, SciencesConf, AureHAL) will be inaccessible (network hardware connection).
Skip to Main content Skip to Navigation
Journal articles

Geomorphic effects of a run-of-the-river dam in a multi-driver context: The case of the Upper Garonne (Central Pyrenees)

Abstract : In this paper, we evaluate morphological changes related to the Plan d'Arem dam (1970), a run-of-river (RoR) dam located on the Upper Garonne (central Pyrenees), and disentangle its morphological effects from other drivers (post-Little Ice Age [LIA] climate change, changes in agricultural practice, catchment afforestation, upstream damming, and bypassing). The work is based on a before-after-control-impact approach, a space-time framework that allowed the stating of four hypotheses distinguishing the effects of the considered dam from other pressures. We first examined the potential reduction to the flow regime (Q L) and bedload transport (Q S) from these pressures, then assessed planimetric changes (1942-2019), vertical evolution (1922-2014), and sediment size within the channel. The results show the river completed adjustments related to post-LIA climate change and catchment afforestation at the beginning of the study period, with channel narrowing affecting the whole study reach and ranging from 0.6% to 1.2% yr − 1. Upstream dams and catchment afforestation reduced both the frequency and magnitude of peak flows and sediment supply, resulting in an increase in the channel narrowing rate on the upstream sub-reach (− 1.2% yr − 1). However, downstream tributaries buffered these changes, and no downstream propagation was found. The effects of the Plan d'Arem started around 15 yr after its construction, with channel narrowing at a rate of 0.9% yr − 1 until the 2010s. The exceptional flood of June 2013 resulted in important channel widening followed by a new period of narrowing upstream of the Plan d'Arem dam, combined with channel stability downstream caused by a new dam management regime (flushing actions). We conclude that the before-after-control-impact approach is effective for isolating the effects of an RoR dam from those of other pressures, and that flushing actions mitigated the effects of the dam.
Complete list of metadata

https://hal.archives-ouvertes.fr/hal-03649379
Contributor : Emilie Gil Connect in order to contact the contributor
Submitted on : Friday, April 22, 2022 - 2:29:52 PM
Last modification on : Tuesday, April 26, 2022 - 3:40:14 AM

File

Bulteau et al 2022 Geomorpholo...
Explicit agreement for this submission

Identifiers

Collections

Citation

Théo Bulteau, Ramon J. Batalla, Emmanuel Chapron, Philippe Valette, Hervé Piégay. Geomorphic effects of a run-of-the-river dam in a multi-driver context: The case of the Upper Garonne (Central Pyrenees). Geomorphology, Elsevier, 2022, 408, 18 p. ⟨10.1016/j.geomorph.2022.108243⟩. ⟨hal-03649379⟩

Share

Metrics

Record views

5

Files downloads

12