Are Large Magnitude Events the Norm in the sedimentary record? Learnings Modern Fluvial Fans
Abstract
Does the timescale at which humans are able to observe the world around us overly control our perception of event frequency and magnitude? Is recurrence interval the right way to approach flood events if sedimentary formations form over hundreds of thousands to millions of years? In this study we examine daily and monthly discharge data from 85 river gauging stations on 69 different fluvial fans around the world. Fluvial fans are a relatively new and somewhat controversial topic in the fluvial sedimentology world as it has been suggested that they form the bulk of the continental fluvial record (Weissmann et al., 2010). They are aerially extensive (103-105 km2), low gradient (~.03°-0.001°), fan-shaped fluvial deposits built by river avulsions. We will first discuss different ways to measure and conceptually think about river discharge variability and then test the link between discharge variability and the formation of fluvial fans. If discharge variability is needed to form fluvial fans, on what time scale does this occur? Does discharge variability on different time scales produces different styles of sedimentation in fluvial fans? What scale of event is geologically formative? Would we expect to see these large magnitude events preserved in the sedimentary record? We will finally compare these learnings to Wolman and Miller's relationship between flow-energy and sediment transport.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP51F2188H
- Keywords:
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- 1824 Geomorphology: general;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 1826 Geomorphology: hillslope;
- HYDROLOGY;
- 1862 Sediment transport;
- HYDROLOGY