Bed disturbance below dams: observations from two Mediterranean rivers
| Autor: | Ramon J. Batalla, Francisco Vallés, Ignacio Andrés-Doménech, Damià Vericat, Gemma Lobera, José Andrés López-Tarazón, Pedro Millán-Romero |
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| Rok vydání: | 2017 |
| Předmět: |
Hydrology
Mediterranean climate River ecosystem 010504 meteorology & atmospheric sciences Flood myth 0208 environmental biotechnology Soil Science Fluvial Sediment 02 engineering and technology Development 01 natural sciences 020801 environmental engineering Habitat Temperate climate Environmental Chemistry Environmental science Sedimentary rock 0105 earth and related environmental sciences General Environmental Science |
| Zdroj: | Land Degradation & Development. 28:2493-2512 |
| ISSN: | 1085-3278 |
| DOI: | 10.1002/ldr.2785 |
| Popis: | River bed disturbance and associated sedimentary processes such as particle mobility are central elements to assess river ecosystem functioning. Dams change river dynamics affecting the magnitude and frequency of biophysical elements that depends on them. This paper examines the effects of two dams different in size, management and location, on the flow regime, flood competence and bed disturbance in two contrasting Mediterranean rivers, the Esera and the Siurana. For this purpose, two reaches on each river were monitored upstream and downstream from reservoirs. Several monitoring and modelling techniques were used to characterize flow competence, particle entrainment, and the volumes of sediments eroded and deposited after floods. The flow regime of the Esera has been modified from nivo-pluvial regime, typical of humid mountainous environments, to that observed in dry-semiarid regions, in which high magnitude but low frequency floods are the dominant processes. Oppositely, the flow regime of the Siurana has changed from a typical Mediterranean stream to a regime observed in more temperate environments, with more permanent and stable flows. Both rivers show notably physical changes, with channels clearly less dynamic below the dams. The lack of competent flows together with the sediment deficit associated with the dams has led to less active fluvial environments (reduced particle mobility and bed scour dynamics), a fact that affects instream habitat structure (more uniform grain size distribution, less physical heterogeneity, more stable flows), overall contributing to the degradation of the stream corridor and the subsequent environmental deterioration of the whole fluvial landscape. |
| Databáze: | OpenAIRE |
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