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Geomorphologic impact of outburst flood cycle in braided gravel-bed rivers: confluence of Colonia and Baker rivers, Patagonia, Chile

Geomorphologic impact of outburst flood cycle in braided gravel-bed rivers: confluence of Colonia and Baker rivers, Patagonia, Chile

Cascio, M., Dussaillant, A., Williams, M., Thorndycraft, V., Bertoldi, W. and Meier, C. (2014) Geomorphologic impact of outburst flood cycle in braided gravel-bed rivers: confluence of Colonia and Baker rivers, Patagonia, Chile. In: British Society of Geomorphology 2014, 1-3 September 2014, Manchester, UK.

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Abstract

Colonia River, as other glacial streams influenced by global warming, is affected by Glacial Lake Outburst Floods (OF). We present a study on geomorphologic features of Colonia River to comprehend the impact of OFs in sedimentary processes, analysing erosion and deposition linked to OF phenomena and frequency (since April 2008, more than 12 OFs have occurred). Interpolation analysis is carried out to create an elevation surface (DTM) from a set of sample measurements, given by contour line (2007 LiDAR) and rtkGPS point (2011 and 2012) data. These were used to create DTMs applying Delaunay triangulation. A comparisons between morphology during the current OF cycle that started on 8 April 2008, and the previous morphology (after 40 years without OFs, since end of previous cycle in 1968), is carried out through the creation of DEMs of Difference (DoDs) based on TINs. We created two DoDs, respectively between 2011-2007 (before/after the OFs cycle) and 2012-2011 (during the cycle, after the events of January and April 2012) to provide a high-resolution, spatially distributed surface model of topographic and volumetric change through time. The floodplain has been classified on the basis of the morphological characteristics: main and secondary channel(s), bars, braided area, island and delta fan features. The changes evidenced in the DoD are segregated according to these categories plus the geomorphic change taking place in each category (using GCD; Wheaton et al 2014). Issues regarding data quantity and quality will be discussed, and implications for the planned mega-dam that would flood the confluence.

Item Type: Conference or Conference Paper (Poster)
Uncontrolled Keywords: Outburst flood, Sediment, DEM of difference, Hydropower
Faculty / Department / Research Group: Faculty of Engineering & Science
Related URLs:
Last Modified: 15 Nov 2017 10:28
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
URI: http://gala.gre.ac.uk/id/eprint/13560

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