Visible and near — infrared reflectance of beach sands: A study on the spectral reflectance/ grain size relationship

The general theory which relates how the grain sizes of particulates influences spectral reflectance has been extended to account for such environmental factors as variable moisture content and iron staining. Utilizing regression analysis, a preliminary grain size predictor model has been developed from the visible and near-infrared reflectance of iron stained quartz beach samples. The model achieved a multiple correlation coefficient squared ($\text{R}{}^2$) of 0.950. It was found to be independent of moisture content and was in complete agreement with the theory. When samples from a non-iron stained beach were used, regression analysis failed to find any significant correlations. This failure can be partly attributed to the lack of an adequate grain size distribution for the non-iron stained samples collected.