Particle Size Distribution and Mean Diameter Characterization of Beach Sand from Haffa, Salalah, Oman

Particle size distribution is an important physical characteristic of coastal sediments, influencing sediment transport, depositional behavior, permeability, packing characteristics, and particle–fluid interactions. The present study investigates the particle size characteristics of beach sand collected from Haffa Beach, Salalah, Sultanate of Oman, using sieve analysis and moment-based particle diameter calculations. A sand sample with an initial mass of 100 g was subjected to particle size separation using sieves with nominal apertures of 2.000, 1.000, 0.710, 0.500, 0.355, and 0.250 mm. The representative particle diameter of the pan fraction was taken as 0.180 mm based on the Tyler method. The recovered sample mass was 99.51 g, corresponding to a mass recovery of 99.51%. The particle size distribution revealed that the fractions retained on the 0.250 and 0.355 mm sieves accounted for approximately 83.08% of the recovered mass, indicating a pronounced concentration of particles within the intermediate size classes. Several moment-based mean particle diameters were evaluated, including the number–length mean (\(D_{10}\)), surface mean (\(D_{20}\)), volume mean (\(D_{30}\)), volume–surface mean (\(D_{32}\)), and volume–mass mean (\(D_{43}\)). Their corresponding values were 0.2405, 0.2480, 0.2567, 0.2751, and 0.3078 mm, respectively. The cumulative particle size distribution was further analyzed to estimate characteristic percentile diameters. Logarithmic interpolation yielded \(d_{30}\), \(d_{50}\), \(d_{60}\), and \(d_{90}\) values of 0.2865, 0.3355, 0.3640, and 0.4749 mm, respectively. The median particle diameter corresponded to medium sand according to the Wentworth grain-size classification. The findings provide a quantitative characterization of the investigated beach sand and demonstrate the relevance of different mean particle diameter definitions for engineering and sedimentological applications. Further analysis of finer particle fractions and grain morphology is recommended to improve sediment sorting assessment and support interpretation of coastal sediment transport processes.