Extraction of morphometric bedform characteristics from profiling sonar datasets recorded in shallow coastal waters of China |
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| Authors: | Han Huang Ya-ping Wang Shu Gao Jian Chen Yang Yang Jian-hua Gao |
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| Institution: | 1. School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, 210093, China
2. Third Institute of Oceanography, State Oceanic Administration, Xiamen, 361005, China
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| Abstract: | The morphological characteristics of small-scale bedforms were measured by means of an acoustic profiling sonar on the Dafeng tidal flat,Jiangsu,in 2009,and in the Jiulong Estuary,Xiamen,in 2010,respectively.The "multi-threshold value" method was utilized to reveal the morphological undulations along which bedforms were present.Analyses of the datasets obtained show that:(1) sand ripples can have irregular shapes,and(2) changes in bedform morphology are small within a single tidal cycle but may be significant over several tidal cycles.Fractal and variogram analyses of the seabed roughness revealed the existence of a significant relationship between current speed and the fractal dimension of the seabed roughness.As current speed increases,seabed roughness increases with a trend of smaller-scale bottom structures being replaced by larger-scale structures.Furthermore,the surface of the larger-scale bottom structures can either become smooth due to the absence of smaller-scale features or become rougher due to the presence of superimposed smaller-scale structures. |
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| Keywords: | ripple profiling sonar bedform seabed roughness fractal dimension variogram method tidal flat Jiulong Estuary |
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