# Estimation of River Velocity and Discharge Based on Video Images and Deep Learning
## 3 Results and Discussion
### Experiments in the Measurement of River Velocity and Discharge
#### 3.3.2 Experiment in Natural Rivers
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Points**} & \multirow{2}{*}{\begin{tabular}{c} **Starting** \\ **Distance/(m)** \\ \end{tabular} } & \multirow{2}{*}{**Depth/(m)**} & \multicolumn{2}{c}{**Vertical Mean**} & \multicolumn{2}{c}{**Partial Mean**} & \multirow{2}{*}{\begin{tabular}{c} **Partial** \\ **Velocity/(m/s)** \\ \end{tabular} } & \multirow{2}{*}{**Partial Area/(m\({}^{2}\))**} & \multicolumn{2}{c}{**Partial**} \\  & & & & & & & \\  & 30–35 & & & 0.88 & 32.8 & 28.9 \\ No. 1 & 35 & 4.46 & 1.25 & & 1.32 & 23.9 & 31.5 \\ No. 2 & 40 & 5.10 & 1.38 & & 1.36 & 25.0 & 34.0 \\ No. 3 & 45 & 4.97 & 1.34 & & 1.18 & 25.5 & 30.1 \\ No. 4 & 50 & 5.30 & 1.03 & & 0.98 & 27.5 & 27.0 \\ No. 5 & 55 & 5.70 & 0.94 & & 0.75 & 10.4 & 7.80 \\ 57 (shore) & & & & & & & \\ \hline \multicolumn{2}{c}{Cross-section area/(m\({}^{2}\)): 145.00} & \multirow{2}{*}{\begin{tabular}{c} \\ Discharge/(m\({}^{3}\)/s): 159.00 \\ Mean velocity/(m/s): 1.10 \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} \\ \\ \end{tabular} } & \multirow{2}{*}{\
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\end{table} 
Table 8: Data of cross-section and the LS25-1 current meter in Panxi. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Indicators**} & \multirow{2}{*}{**Points**} & \multicolumn{5}{c}{**Measured Values/(m/s)**} & \multicolumn{5}{c}{**Relative Error/(\%)**} \\ \cline{3-11}  & & \multicolumn{1}{c}{**Current**} & \multicolumn{1}{c}{**GTM**} & \multicolumn{1}{c}{**FFT**} & \multicolumn{1}{c}{**FD-DIS-G**} & \multicolumn{1}{c}{**New**} & \multirow{2}{*}{**GTM**} & \multicolumn{1}{c}{**FFT**} & \multicolumn{1}{c}{**FD-DIS-G**} & \multicolumn{1}{c}{**New**} \\  & & **Meter** & & & & & & & **DIS-G** & **Method** \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Vertical \\ mean velocity/(m/s) \\ \end{tabular} } & No. 1 & 1.25 & 0.80 & 0.99 & 1.11 & 1.13 & 36.00\% & 20.80\% & 11.20\% & 9.60\% \\  & No. 2 & 1.38 & 1.16 & 1.46 & 1.04 & 1.35 & 15.94\% & 5.80\% & 24.64\% & 2.17\% \\  & No. 3 & 1.34 & 0.84 & 1.21 & 0.86 & 1.35 & 37.31\% & 9.70\% & 35.82\% & 0.75\% \\  & No. 4 & 1.03 & 0.58 & 0.84 & 0.99 & 1.07 & 43.69\% & 18.45\% & 3.88\% & 3.88\% \\  & No. 5 & 0.94 & 0.34 & 0.63 & 1.33 & 0.83 & 63.83\% & 32.98\% & 41.49\% & 11.70\% \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Comparison of measured results and errors of different methods in Panxi. Figure 12b clearly shows the time consumption of the four algorithms. Compared with the BGT, FFT, and FD-DIS-G methods, the running time of the new method is the longest. However, it can provide more reliable measurement results, and the increased time is completely acceptable in the monitoring work of hydrological stations. The above two sets of experiments demonstrate that the proposed method is well-suited for monitoring river velocity and discharge in both artificial and natural rivers, and the reliable measurement results can be obtained in complex natural environments. Further research and verification are required to establish its applicability under other river conditions. The wide universality of the proposed method is further confirmed at the Mengxing hydrological station in Lincang City, Yunnan province. The edge of the river bank is covered with vegetation and weeds, and there are standing signs and guardrails along the shore. During the measurement process, a DS-2 DC1225-I3/15 camera produced by Hikvision is installed at a location that is 39.4 m, 35.8 m, 80.3 m, and 85.6 m away from points A, B, C, and D, respectively.