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Descripción
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| Geomorphic responses to damming are primarily determined by the magnitude of 15 sediment transport and sediment supply alteration and by the resulting change in the 16 balance between the two. The former change is caused by alterations in the flow regime 17 that are caused by reservoir operations. Flow regime changes also affect the distribution 18 and amount of riparian vegetation that, in turn, also may enhance geomorphic 19 responses. The latter change is caused by sediment trapping in reservoirs and by the 20 magnitude of sediment supply from watersheds that are downstream from the dam. We 21 examined the bio-geomorphic responses to flow regulation along a Mediterranean 22 stream located in an agricultural area of southern Spain where there is significant fine 23 sediment erosion from adjacent hillsides. We measured changes in active channel width 24 and riparian corridor features during the last fifty years, based on field work and aerial 25 photographs surveys from 1956, 1984 and 2004. We assessed the hydrological 26 alteration and sediment delivery trends linked to dam operation and land use changes. 27 Channel narrowing of nearly 75% and 30% reduction in total corridor area, together with average accretion rates of 0.045 m y-1 28 and vegetation encroachment with a 305% 29 increase of mature forest occurred between 1956 and 2004. Causal linkages were 30 attributed to the strong reduction of peak flows and transport capacity of flows, together 31 with land-use changes that likely promoted increased fine sediment delivery. Vegetation 32 overgrowth favored by increased summer flows could contribute to the narrowing and 33 aggradation processes. Our results differ from channel responses to damming in 34 Mediterranean regions dominated by steep gradient gravel bed rivers, and highlight the 35 relevance of topography and land- use affecting the sediment regime downstream from 36 the dams. We argue for a more holistic approach of water resources and land-use 37 management at the catchment scale in order to understand the synergistic effects of 38 dams, sediment supply, and vegetation growth, and to design appropriate flow 39 regulation schemes to cope with irrigation demands and flood risk management in 40 Mediterranean streams | |
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Internacional
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JCR del ISI
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Título de la revista
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Journal of Hydrology |
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ISSN
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0022-1694 |
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Factor de impacto JCR
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2,693 |
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Información de impacto
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Volumen
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528 |
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DOI
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http://dx.doi.org/10.1016/j.jhydrol.2015.06.065 |
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Número de revista
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Desde la página
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751 |
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Hasta la página
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762 |
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Mes
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Ranking
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