New Bedform Phase Diagrams and Discriminant Functions for Formative Conditions of Bedforms in Open-Channel Flows
| Autor: | Hajime Naruse, Miwa Yokokawa, Enrica Viparelli, Koji Ohata |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Mahalanobis distance
Bedform 010504 meteorology & atmospheric sciences Hydraulics Fluvial Geometry 010502 geochemistry & geophysics Linear discriminant analysis 01 natural sciences Physics::Geophysics law.invention Sedimentary structures Open-channel flow Geophysics Discriminant law Geomorphology Geology 0105 earth and related environmental sciences Earth-Surface Processes |
| Zdroj: | Journal of Geophysical Research: Earth Surface. 122:2139-2158 |
| ISSN: | 2169-9003 |
| DOI: | 10.1002/2017jf004290 |
| Popis: | Understanding of the formative conditions of fluvial bedforms is significant for both river management and geological studies. Diagrams showing bedform stability conditions have been widely used for the analyses of sedimentary structures. However, the use of discriminants to determine the boundaries of different bedforms regimes has not yet been explored. In this study, we use discriminant functions to describe formative conditions for a range of fluvial bedforms in a 3D dimensionless parametric space. We do this by means of discriminant analysis using the Mahalanobis distance. We analyzed 3793 available laboratory and field data, and used these to produce new bedform phase diagrams. These diagrams employ three dimensionless parameters representing properties of flow hydraulics and sediment particles as their axes. The discriminant functions for bedform regimes proposed herein are quadratic functions of three dimensionless parameters, and are expressed as curved surfaces in 3D space. These empirical functions can be used to estimate paleoflow velocities from sedimentary structures. As an example of the reconstruction of hydraulic conditions, we calculated the paleoflow velocity of the 2011 Tohoku-Oki tsunami backwash flow from the sedimentary structures of the tsunami deposit. In so doing, we successfully reconstructed reasonable values of the paleoflow velocities. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text