The impact of a major Quaternary river capture on the alluvial sediments of a beheaded river system, the Rio Alias SE Spain
AffiliationUniversity College Chester ; University of Liverpool ; University College Chester
MetadataShow full item record
AbstractThis article discusses a major river capture event within the Sorbas Basin (c.70 ka) which created a situation whereby the Rio Alias abruptly lost c. 70% of its drainage area and this led to a significant modification of the fluvial system in both upstream and downstream zones on the capturing stream, and downstream on the beheaded system.
CitationGeomorphology, 2007, 84(3-4), pp. 344-356
DescriptionThis article is not available through ChesterRep.
SponsorsThis article was submitted to the RAE2008 for the University of Chester - Geography & Environmental Studies.
Showing items related by title, author, creator and subject.
Impact of large instream logs on river bank erosionZhang, Nuosha; Rutherfurd, Ian; Marren, Philip M.; University of Melbourne (Zhang, Rutherfurd); University of Chester (Marren) (11th International Symposium on Ecolhydraulics / asn events, 2016-02)There has been abundant research into the effect of tree roots on stabilizing river banks, and also on the effect of trees on bed-scour after they have fallen into the stream, but there is little research into the effect of instream logs on bank erosion. Here we develop the hydraulic theory that predicts local and reach scale bank erosion associated with instream logs with various configurations and distributions and conclude that individual log can increase local bank erosion, but multiple logs can reduce overall reach erosion. Where there is consistent bank strength, the local erosion varies in a non-linear way with the angle, size and position of the log. The reach scale effect of multiple logs depends on the distribution of logs and the proportion of the reach occupied by logs. Erosion effects of instream logs are difficult to measure. We are testing the above theory of erosion associated with instream logs in a series of anabranches of different sizes that experience consistent irrigation flows each year (on the Murray River in SE Australia). These channels have high erosion rates, abundant logs, and are like a giant flume that allows us to measure erosion processes, as well as hydraulics, in a controlled setting.
The Potential for Dams to Impact Lowland Meandering River Floodplain GeomorphologyMarren, Philip M.; Grove, James R.; Webb, J. Angus; Stewardson, Michael J.; University of Melbourne (Hindawi Publishing Corporation, 2014-01-22)The majority of the world’s floodplains are dammed. Although some implications of dams for riverine ecology and for river channel morphology are well understood, there is less research on the impacts of dams on floodplain geomorphology. We review studies from dammed and undammed rivers and include influences on vertical and lateral accretion, meander migration and cutoff formation, avulsion, and interactions with floodplain vegetation.The results are synthesized into a conceptual model of the effects of dams on the major geomorphic influences on floodplain development.This model is used to assess the likely consequences of eight damand flow regulation scenarios for floodplain geomorphology. Sediment starvation downstream of dams has perhaps the greatest potential to impact on floodplain development. Such effects will persist further downstream where tributary sediment inputs are relatively low and there is minimal buffering by alluvial sediment stores.We can identify several ways in which floodplains might potentially be affected by dams, with varying degrees of confidence, including a distinction between passive impacts (floodplain disconnection) and active impacts (changes in geomorphological processes and functioning). These active processes are likely to have more serious implications for floodplain function and emphasize both the need for future research and the need for an “environmental sediment regime” to operate alongside environmental flows.
Channel pattern of proglacial rivers: topographic forcing due to glacier retreatMarren, Philip M.; Toomath, Shamus C.; University of Melbourne (Wiley, 2014-03-06)Glacier retreat leads to changes in channel pattern during deglaciation, in response to changing water, sediment and base level controls. Recent ongoing retreat at Skaftafellsjökull, Iceland (c. 50m per year since 1998) has resulted in the formation of a sequence of river terraces, and several changes in river channel pattern. This paper compares widely used models of river channel pattern against the changes observed at Skaftafellsjökull. Doing this reveals the role of topographic forcing in determining proglacial channel pattern, whilst examining the predictive power and limitations of the various approaches to classifying river channels. Topography was found to play a large role in determining channel pattern in proglacial environments for two reasons: firstly, glacier retreat forces rivers to flow through confined moraine reaches. In these reaches, channels which theory predicts should be braided are forced to adopt a single channel. Secondly, proximal incision of proglacial rivers, accompanied by downstream aggradation, leads to changes in slope which force the river to cross channel pattern thresholds. The findings of this work indicate that in the short term, the majority of channel pattern change in proglacial rivers is due to topographic forcing, and that changes due to changing hydrology and sediment supply are initially relatively minor, although likely to increase in significance as deglaciation progresses. These findings have implications for palaeohydraulic studies, where changes in proglacial channel pattern are frequently interpretedas being due to changes in water or sediment supply. This paper shows that channel pattern can change at timescales faster than hydrological or sediment budget changes usually occur, in association with relatively minor changes in glacier mass balance.