RESEARCH ON THE DISTRIBUTION OF PARTICLE SIZE ON COASTAL BARCHAN: A CASE STUDY OF CHANGLI GOLD COAST

Changli Gold Coast in Hebei Province is a coastal dune region with diversified dune type, large dune area and typical dune shapes in China. At Changli Gold Coast, 42 samples of particle size were collected on a coastal barchan, which was a typical coastal barchan chosen from all the barchans in this research region. All the samples of particle size were analysed and the particle-size parameters of various samples were figured out. The results showed grain size on the coastal barchan was middle sand of good sorting, symmetrical skewness and middle degree kurtosis. It was also found that the mean particle size at different sites of the typical coastal barchan showed an obvious change. The distribution characteristics of particle size on the coastal barchan showed that the particle size became coarse from windward slope base to dune crest, but became fine on the leeward slope and then became coarse again at the leeward slope base, and the dune crest had coarsest particle size and leeward slope had finest particle size. The particle-size distribution of barchan in the Changli Gold Coast exhibited a model with coarsest sand materials occurring at the dune crest. The distribution pattern of particle size on the coastal barchan at Changli in Hebei Province mainly resulted from the combined effects of alternating variation of the regional prevailing wind directions and strong wind direction and wind fore difference, asymmetry on both sides of the dune, and concave shape of windward slope.