Nam, J.; Hong, S.; Lee, Y., and Kim, I., 2021. Correlation analysis between color and grain size of sand using a colorimeter. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 201–205. Coconut Creek (Florida), ISSN 0749-0208.
To determine the cause of coastline changes, it is necessary to monitor various parameters such as wave data, changes in water depth, seabed topography and quality, as well as sea currents. This study aims to derive a correlation between grain size and color of sand on a coast undergoing erosion in Namae 3-ri∼Sodol beach. Therefore, for a period of six years (2013 to 2018), the depths of the foam zone, the breaking band, and other factors were divided for each cross-base line (DL(±) 0.00 m, DL(-) 3.00 m, DL(-) 6.00 m, and DL(-) 9.00 m). Seabed samples were collected from four vertices, and the median particle size and color characteristics of sand were recorded. Results showed that the average D50 particle sizes for DL(±) 0.00 m, DL(-) 3.00 m, DL(-) 6.00 m, and DL(-) 9.00 m were 0.615 mm, 0.432 mm, 0.416 mm, and 0.410 mm, respectively. In addition, the color of the sand that was passed through the colorimeter is represented by L* (white-black), a* (green-red), and b* (yellow-blue); these colors were expressed as a number to present a unique value. DL(±) 0.00 m = L* 61.12082, a* 5.757663, b* 17.93326; DL(-) 3.00 m = L* 61.81803, a* 5.03382, b* 16.79151; DL(-) 6.00 m = L* 61.74719, a* 4.886109, b* 16.54382; and DL(-) 9.00 m = L* 61.70353, a* 4.815222, and b* 16.42189. Furthermore, the sand color values a* and b* were coordinated, distributed on the beach, and then a color range converted to the value of the radius of the polar coordinate (r) was presented and compared with the particle size. To compare the a* and b* values with the sand particle size, r is expressed as a first-order function. The R-square of the first-order function was 0.9411, which was found to be highly reliable, and the exponential function was found to have a reliability of 0.5573. This result shows that the a* and b* values can be inferred according to the particle size of the sand.