the basic modes of particle motion are rolling motion, sliding motion and saltation motion. Many researchers attempted to predict the rate of bed load transport. The first successful development was proposed by P.F.D. du Boys in 1879. Although his model of sediment transport was incomplete, the proposed relationship for bedload transport rate (Table 10.1) proved to be in good agreement with a large amount of experimental measurements The sediment transport rate may be measured by weight (units: N/s), by mass (units: kg/ s) or by volume (units: m3 /s). In practice the sediment transport rate is often expressed per unit width and is measured