Publication Date:
2011-05-03
Description:
In this paper the spatial and temporal responses of Someşu Mic River (Romania) to natural and anthropogenic controls over the past 150 years, are analyzed, based on a series of morphometric parameters extracted from five successive sets of topographic maps and one set of orthophotos. Prior to the intensive hydrotechnical interventions of the last four decades, the river was characterised by a complex alternation of different channel types, resulting in a mixture of alluvial and mixed sinuous - meandering - sinuous anabranched - meandering anabranched reaches, each a few hundred meters to a few kilometres long. The main cause for this spatial behavior was the local geology. Its effects were intensified by a larger scale slope slightly higher than along a longitudinal profile with normal concavity, as a consequence of the presence of a 400 m elevation knick-point located in the catchment's area. Channel metamorphosis by canalisation, diminishing / elimination of overflows and medium scale avulsions by changes in flow regimes (dams) and the presence of dykes in the floodplain perimeter, channel narrowing (43%) and incision (at least after 1945) downstream from dams, along, and probably because of in-channel gravel mining, are the main anthropically induced changes along Someşu Mic River. Even if human impact is important, both at the drainage basin scale and along Someşu Mic River, it has only local impacts, subordinated to climate. The low level of human impact on this river could be the consequence of the higher general slope downstream from 400 m elevation knick-point, which probably forces the positioning of its effects under an important internal threshold of the fluvial system. This boundary condition defines Someşu Mic River as an atypical river. Also, the study supports the idea that climate has an important role in the post-LIA rivers' behavior. Copyright © 2011 John Wiley & Sons, Ltd.
Print ISSN:
0197-9337
Electronic ISSN:
1096-9837
Topics:
Geography
,
Geosciences
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