## 6 Conclusions
The world is diverse in topography and climate, which might influence the accuracy of SPPs at different levels in various regions. Therefore, the quality of the latest IMERG and GSMaP SPPs, as well as their hydrological utility in other regions of the world, must be assessed and compared. The assessment framework proposed in this study is expected to be applicable to other river basins. To implement this framework for assessment at sub-daily time scales, two critical issues should be addressed. First, obtaining the ground precipitation and observed streamflow data in shorter-than-daily time intervals is prerequisite. Such data might be easily accessed in most watersheds of the developed countries. However, collecting these data might be difficult in many underdeveloped regions owing to the limited local infrastructure investment for ground hydrometeorological monitoring, and this largely restricts the applicability of the assessment framework in these regions. Second, given that hydrological models generally have certain preconditions for applications, selecting a suitable model for hydrological evaluation of SPPs according to local land surface and hydrometeorological features and data acquisition conditions is an effective measure to reduce the uncertainty from hydrological model structure and improve the reliability of the assessment. This study involves large uncertainties from precipitation input, parameter calibration, and hydrological model structure. Future work will focus on reducing and quantifying these uncertainties, such as bias-correcting SPPs, extending discharge data length for parameter calibration, using the GLUE scheme to explicitly quantify the effect of parameter equifinality, employing different hydrological models, and conducting multi-model simulations and comparisons. Additionally, future work will also entail assessing more basins in Southeast Asian countries using the error decomposition scheme [85], which separates the errors of SPPs into three independent components (hit bias, missed precipitation, and false precipitation) and helps better track the error sources associated with the satellite retrieval processes. The following are available online at [[http://www.mdpi.com/2072-4292/11/2/140/s1](http://www.mdpi.com/2072-4292/11/2/140/s1)]([http://www.mdpi.com/2072-4292/11/2/140/s1](http://www.mdpi.com/2072-4292/11/2/140/s1)), Figures S1-S4: Performance of 3-hourly discharge simulations from 1 April 2014 to 31 December 2016 at the Hkamti, Homalin, Mawlaik, and Kalewa hydrological stations using the gauge-based gridded precipitation data set, 3B42 RT, 3B42V7, and IMERG-F SPPs under two simulation scenarios, Figures S5-S8: Taylor diagrams showing the comparison of the simulated discharge at the Hkamti, Homalin, Mawlaik, and Kalewa stations using the rain-gauge-based precipitation data set, 3B42 RT, 3B42V7, and IMERG-F SPPs with respect to the observed discharge data: (a) Scenario I and (b) Scenario II, Table S1: Physical meaning and sensitivity of the GXAJ model parameters and their parameter values calibrated using the gauge-based precipitation data set, 3B42 RT, 3B42V7, and IMERG-F SPPs, Table S2: Summary of previous studies regarding the hydrological utility of the GPM-era SPPs. Conceptualization, F.Y. ; methodology, F.Y. ; writing--original draft preparation, F.Y. ; funding acquisition, F.Y. and L.R. ; investigation: F.Y., L.Z., K.M.W.S., and C.Z. ; data curation: L.Z. and K.M.W.S. ; visualization, L.Z. ; writing--review and editing, L.R.,Y.Z., S.J., and Y.L. This research was funded by the National Key Research and Development Program (Grant No. 2016 YFA0601500) approved by the Ministry of Science and Technology of China; the National Natural Science Foundation of China (Grant Nos. 51779070, 41730750, and 51579066); the Natural Science Fundation of Jiangsu Province (Grand No. BK20150815), the 111 Project from the Ministry of Education and State Administration of Foreign Experts Affairs, P. R. China (Grant No. B08048); and the Fundamental Research Funds for the Central Universities (Grand No.