## 3 Results and Discussion
### Streamflow Simulation Scenarios and Results
#### 3.3.3 Scenario III: Comparison of Manually Controlled Ensemble Simulation for the Two River Basins  
In Scenario III, we consider merging streamflow simulations obtained by individual satellite/reanalysis precipitation datasets as another alternative. In brief, Average Streamflow 01 and 1 are arithmetic means of three selected streamflow simulations driven by each single precipitation dataset (TMPA-3B42V7, IMERG-cal, and GSMaP) under Scenario I and Scenario II, respectively. Furthermore, Average Streamflow 02 and 2 are arithmetic means of three selected streamflow simulations driven by each single precipitation dataset (TMPA-3B42 RT, IMERG-uncal, and ERA5) under Scenario I and Scenario II, respectively.  
Table 8 provides the values of four indicators (NSCE, BIAS, CC, and RMSE) of the new direct average streamflow series over these two river basins, respectively. For the Beijing River Basin, when compared with the hydrologic modeling performances in Tables 4 and 6, all the NSCE and CC values of different Average Streamflow series were nearly the same as those of their corresponding Average Rain 1 or 2 products. Meanwhile, all the BIAS and RMSE values of different Average Streamflow series were reduced slightly under Scenario III. For the Dongjiang River Basin, when compared with the hydrologic modeling performances in Tables 5 and 7, all the evaluation values (NSCE, BIAS, CC, and RMSE) for different Average Streamflow series were slightly better than those of their corresponding Average Rain products. In this section, it is suggested that merging streamflow simulations obtained by individual satellite/reanalysis precipitation datasets as well as merging precipitation datasets can represent a good alternative for hydrological applications across the study area.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Watershed** &
\begin{tabular}{c} **Streamflow** \\ **Simulation** \\ \end{tabular} & **Period** & **Merged Streamflow** & **NSCE** & **BIAS (\%)** & **CC** & **RMSE (m\({}^{3}\)/s)** \\ \hline \multirow{6}{*}{Beijing} & Under & Validation & Average Streamflow 01 & 0.77 & \(-\)11.20 & 0.89 & 739.01 \\  & Scenario I & Validation & Average Streamflow 02 & 0.74 & \(-\)8.52 & 0.87 & 793.20 \\ \cline{2-7}  & \multirow{4}{*}{Under} & Calibration & Average Streamflow 1 & 0.87 & \(-\)10.02 & 0.94 & 574.63 \\  & & Validation & Average Streamflow 1 & 0.78 & \(-\)9.59 & 0.89 & 729.99 \\ \cline{2-7}  & \multirow{2}{*}{Scenario II} & Calibration & Average Streamflow 2 & 0.85 & \(-\)12.83 & 0.92 & 635.31 \\  & & Validation & Average Streamflow 2 & 0.74 & \(-\)9.94 & 0.86 & 799.77 \\ \cline{2-7}  & \multirow{2}{*}{Under} & Validation & Average Streamflow 01 & 0.71 & \(-\)14.77 & 0.86 & 333.71 \\  & & Validation & Average Streamflow 02 & 0.70 & \(-\)12.10 & 0.85 & 335.84 \\ \cline{2-7}  & \multirow{2}{*}{Under} & Calibration & Average Streamflow 1 & 0.83 & \(-\)3.25 & 0.91 & 343.56 \\ \cline{2-7}  & \multirow{2}{*}{Under} & Validation & merged Streamflow 1 & 0.73 & \(-\)5.71 & 0.86 & 320.07 \\ \cline{2-7}  & & Calibration & Average Streamflow 2 & 0.82 & \(-\)5.30 & 0.91 & 358.63 \\ \cline{2-7}  & \multirow{2}{*}{Scenario II} & Calibration & Average Streamflow 2 & 0.71 & \(-\)11.24 & 0.85 & 334.92 \\ \cline{2-7}  & & \multicolumn{1}{c}{} & & & & \\ \end{tabular}
\end{table}
Table 8: Comparison of the averaged streamflow simulation during the calibration (1 April 2006–31 December 2010) and validation (1 January 2011–31 December 2018) periods under Scenario III for the two river basins.