Effects of Damming on Long‐Term Development of Fluvial Islands, Elbe River (N Czechia). (14th October 2016)

• Record Type: Journal Article
• Authors: Raška, P.; Dolejš, M.; Hofmanová, M.
• Is Part Of: River research and applications. Volume 33:Number 4(2017)
• Page Start: 471
• Page End: 482
• Publication Date: 2016-10-14
• Subjects: river damming -- channel planform -- fluvial islands -- long‐term development; Rivers -- Regulation -- Periodicals; Rivers -- Periodicals; 551.483
• DOI: 10.1002/rra.3104
• Languages: English
• ISSNs: 1535-1459

Abstract

Abstract: Damming and water impoundment have fundamental influences on the geomorphology and ecological processes of lotic systems. Although these engineering projects affect all segments of the river channel, fluvial (mid‐channel, river) islands are among the most threatened features because of their link to both hydrostatic and hydrodynamic effects of damming. In this study, we used historical maps (1843, 1852) and aerial photos (1954, 2014), as well as other written and iconographic documentary sources, to document the long‐term development of the fluvial islands and channel planform in the Lower Labe (Elbe) River area (Northern Czechia) over the past ~170 years. Our results indicate the decrease of fluvial islands from 16 (1843), resp. 20 (1852) in the mid‐19 th century to eight in 1954, and finally to five in 2014. Most islands have disappeared because of the construction of dams and lock chambers for the purpose of river navigation in the first half of the 20th century. The possible processes responsible for island extinction in individual river segments include sediment starvation (downstream of the dam), erosion by overflow (near upstream of the dam) and decreased flow in inter‐island branches (far upstream of the dam). The islands most susceptible to extinction are those with a smaller size and elliptical or irregular shape. Based on visual evaluation of historical photos and survey of present day temporary islands, the medium and fine sedimentary fraction and absence of a vegetation cover seem to be another predictor of island extinction. Finally, we stress the relevance of our findings for the current discussion on the construction of new lock chambers downstream of the study area. Copyright © 2016 John Wiley & Sons, Ltd.