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  • 标题:Characteristics of Point-Bar Development under the Influence of a Dam: Case Study on the Dráva River at Sigetec, Croatia
  • 作者:Tímea Kiss ; Márton Balogh
  • 期刊名称:Journal of Environmental Geography
  • 电子版ISSN:2060-467X
  • 出版年度:2015
  • 卷号:8
  • 期号:1-2
  • 页码:23-30
  • DOI:10.1515/jengeo-2015-0003
  • 出版社:Walter de Gruyter GmbH
  • 摘要:

    Before the extensive engineering works the Dráva River had braided pattern. However in the 19-20th centuries river regulation works became widespread, thus meanders were cut off, side-channels were blocked and hydroelectric power plants were completed. These human impacts significantly changed the hydro-morphology of the river. The aim of the present research is to analyse meander development and the formation of a point-bar from the point of view of indirect human impact. Series of maps and ortho-photos representing the period of 1870-2011 were used to quantify the longterm meander development, rate of bank erosion and point-bar aggradation. Besides, at-a-site erosion measurements and grain-size analysis were also carried out. As the result of reservoir constructions during the last 145 years floods almost totally disappeared, as their return period increased to 5-15 years and their duration decreased to 1-2 days. The channel pattern had changed from braided to sinuous and to meandering, thus the rate of bank erosion increased from 3.7 m/y to 32 m/y. On the upstream part of the point-bar the maximum grain size is 49.7-83.4 mm and the mean particle size is 7.6 mm, whilst on the downstream part the maximum grain size was only 39.7-39.9 mm and mean sediment size decreased to 6.1 mm. Due to the coarse sediment supply and the decreasing stream energy the point-bars develop quickly upstream and laterally too.

  • 关键词:point-bar ; meander development ; gravel-bar ; grain-size distribution ; effects of dams
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