# Experiments on Longitudinal and Transverse Bedload Transport in Sine-Generated Meandering Channels
## 3 Results
### Point Bar Composition  
In our flumes, during the formation of point bars, the B\({}_{2}\) bends continuously receive D\({}_{1}\), D\({}_{2}\) and D\({}_{4}\) grains and lose D\({}_{3}\) grains. The white grains are relatively rare; therefore, they can be neglected. Table 4 summarized the proportions of D\({}_{1}\), D\({}_{2}\) and D\({}_{4}\) grains in the point bars in the B\({}_{2}\) bends of the 30\({}^{\circ}\) and 110\({}^{\circ}\) flumes. Our statistics show that there are 15.9 \(\times\) 10\({}^{-4}\) m\({}^{3}\) of D\({}_{1}\), 5 \(\times\) 10\({}^{-4}\) m\({}^{3}\) of D\({}_{2}\), and 7.1 \(\times\) 10\({}^{-4}\) m\({}^{3}\) of D\({}_{4}\) that contribute to the B\({}_{2}\) bend point bar of the 110\({}^{\circ}\) flume. It indicates that for the point bars of highly curved channels, most building material (about 73% in this case) comes from upstream bend. Compared to D\({}_{2}\), D\({}_{1}\) (i.e., the material of the outer side of the upstream bend) makes a much larger contribution (about three times in quantity) to shaping the point bar of the B\({}_{2}\) bend. Besides, about 40% D\({}_{1}\) and 30% D\({}_{2}\) grains were transported toward the concave bank of the B\({}_{2}\) bend, compensating for the local grain loss and maintaining the bed elevation. Figure 4: Accumulated SV of the colored grains (**a**) along the B\({}_{2}\) bend of the 110\({}^{\circ}\) flume; (**b**) along the B\({}_{3}\) bend of the 110\({}^{\circ}\) flume. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline  & & \multicolumn{4}{c}{**30\({}^{\circ}\)**} & \multicolumn{4}{c}{**110\({}^{\circ}\)**} \\ \cline{3-11} \multirow{2}{*}{**Bend**} & \multirow{2}{*}{**Section**} & \multicolumn{2}{c}{**D\({}_{1}\)**} & \multicolumn{2}{c}{**D\({}_{2}\)**} & \multicolumn{2}{c}{**D\({}_{1}\)**} & \multicolumn{2}{c}{**D\({}_{2}\)**} \\ \cline{3-11}  & & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Section**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} \\ \cline{3-11}  & & & & & & & & & & & \\ \hline B\({}_{1}\) & 5–13 & \(-\)3.5 & 1.0 & 0.6 & \(-\)5.5 & 13–37 & \(-\)34.9 & 9.8 & 2.6 & \(-\)18.1 \\ B\({}_{2}\) & 13–21 & 0.9 & 0.9 & 2.9 & 2.3 & 37–61 & 15.9 & 11.3 & 5.0 & 2.0 \\ B\({}_{3}\) & 21–29 & 0.8 & 0.4 & 0.3 & 0.8 & 61–85 & 2.7 & 2.4 & 0.2 & 0.2 \\ \hline \multirow{3}{*}{**Bend**} & \multicolumn{4}{c}{**30\({}^{\circ}\)**} & \multicolumn{4}{c}{**110\({}^{\circ}\)**} \\ \cline{3-11}  & & \multicolumn{4}{c}{**D\({}_{3}\)**} & \multicolumn{4}{c}{**D\({}_{4}\)**} & \multicolumn{4}{c}{**D\({}_{3}\)**} & \multicolumn{4}{c}{**D\({}_{4}\)**} \\ \cline{3-11}  & & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} \\ \cline{3-11}  & & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Right Bank**} & \multicolumn{2}{c}{**Bank**} \\ \cline{3-11}  & & \multirow{2}{*}{**Left Bank**} & \multicolumn{2}{c}{**Bank**} & \multicolumn{2}{c}{**Bank**} & \multicolumn{2}{c}{**Left Bank**} & \multicolumn{2}{c}{**Bank**} & \multicolumn{2}{c}{**Left Bank**} & \multicolumn{2}{c}{**Bank**} \\ \hline B\({}_{2}\) & 13–21 & \(-\)5.2 & 0.5 & 0.6 & \(-\)3.1 & 37–61 & \(-\)14.0 & 11.3 & 5.0 & 2.0 \\ B\({}_{3}\) & 21–29 & 2.7 & 0.5 & 1.2 & 0.7 & 61–85 & 4.1 & 2.8 & 10.4 & 12.5 \\ \hline \end{tabular}
\end{table} 
Table 3: Gain and loss of colored grains in the B\({}_{1}\)–B\({}_{3}\) bends (unit: 10\({}^{-4}\) m\({}^{3}\), negative values means loss and positive means gain).