Theoretical and experimental study of changes in channels bottoms due to sediment transport

In this study, numerous experiments are carried out in the experimental system designed and built in the Hydraulics Laboratory of Dokuz Eylül University. It involves a rectangular flume of 18.6 m length and 0.80 m width. The water supply tank has o volume of 27 m3, and water is conveyed by means of a pump whose discharge can be adjusted. The bed forms are measured in steady and unsteady flow conditions with six different steady discharges and by generating two different hydrographs. The sediment is bimodal, composed from two sands with D50 = 0.45 mm and D50 = 4.8 mm. Its median size D50 and standard deviation g are 1.03 mm and 2.62, respectively. The criteria about the inception of the motion given in the literature are compared with the experimental findings. The bed forms are identified according to the classifications established from previous studies carried out by numerous researchers and their measured values are compared with those calculated from the empirical relations given in the relevant literature.The bed loads are measured by sieves placed at the downstream end of the channel. The accumulated material is dried and weighed after each experiment. These experimental results obtained through the TÜBİTAK 106M274 project are compared with those found from various charts and end empirical formulas. The experimental findings about the inception of the motion revealed a total compatibility with existing charts and empirical relations. In the classification of bed forms, the experimental results are in excellent accord with the charts formed by Engelund and Hansen (1966), Zanke (1972) and Southard and Boguchwal (1990).The empirical relation on the height of bed forms proposed by Yalın (1972) suits better with experimental results, and the empirical relation about bed form lengths given by Van Rijn (1993) is in better accordance with the experimental findings of this study. The experimental results concerning the alternate bars are compatible with those deduced from available charts and empirical relations.