• Journal of the Korean association of regional geographers
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• v.22 no.4
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• pp.887-911
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• 2016

The empirical law that transverse dunes migrate inversely with their heights leads logically to the prediction that multiple dune ridges will converse to a single huge dune by merging. This contradicts the existence of the steady state dune fields on the Earth. The recent studies have emphasized dune collisions as a key mechanism to the stability of dunefield. The roles of wind shadow aspect ratio, however, have yet to be fully explored. This research aims to investigate the potential roles of wind shadow aspect ratio in the dynamical behaviors of transverse dune field. The simplified model is established for this, based upon allometric properties of transverse dunes, wind speedup on the stoss slope and sand trapping efficiency. The derived governing equations can be transformed to the zoning criteria and vector field for dune evolution. The dynamics analysis indicates that wind shadow aspect ratios do not produce convergent areas on the behavior space; rather, they just act as one of the factors that affect the trajectories of dune evolution. Though the model cannot represent the stability of dune field, but seem to produce a reasonable exponent for dune spacing-height relations.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.608-624
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• 2010

Morphological surveys of southern Gyeonggi Bay in the Yellow Sea were conducted for2 years (2006 and 2007) by using multibeam echosounder for investigating the morphological features of bedforms. The subaqueous dunes are shown in various shapes (A~F type) and continuous spectrum of heights and lengths of transverse-to-current dunes on the wide range of sedimentary types. The height-length power-law correlation of dunes is $H_{mean}=0.0393L^{0.8984}$ (r=0.66). The comparison between Flemming (1988)'s correlation and height-length correlation of this study indicates that the subaqueous dunes in the study area are equilibrated in the present hydrological and sedimentary environment. The major controlling factors to thedevelopment and maintenance of subaqueous dunes are both strong tidal currents and the abundant availability of sand. Marine sand mining, artificial impact, changes from the original shape to an irregular shape of the subaqueous dunes with a shorter wavelength and lower height, which has influence on the development and maintenance of bedform because it causes a decrease of the availability of sediment. Water depth and sedimentary characteristics, and othercontrolling factors seem to play limited roles in the development and maintenance of subaqueous dunes.