## 3 Results and Discussion  
### Comparison of Rainfall from Rain Gauges and Other Precipitation Products  
Figure 4 illustrates the comparison of observed rainfall against the different precipitation products for the three stations. The dashed lines in the annual series are the extracted precipitation products, whereas the straight lines (blue coloured) are the observed annual rainfall in respective stations. The rainfall patterns are somewhat matching to each other in a particular year. The peaks and troughs are somewhat coinciding with each other for different precipitation products. However, a perfect match is not visible. Therefore, it justifies the requirement of this research in order to identify better precipitation products in the absence of observed rainfall records.  
Figure 3: Hydrograph obtained during calibration (2007 to 2010) and validation (2011 to 2014) at kh.92 [58].  
Figure 4: _Cont_.  
In addition, monthly variations of precipitation products for selected years are given for each station. The years 2005, 2011, and 2012 are selected for station 640112 deepening on the peaks and trough of the annual precipitations. Similarly, three years are presented for their monthly precipitation variation for 640122 and 640150 stations.  
The 3B42-RT and CMORPH precipitation products under-estimated the actual annual rainfall for the 640112 station. However, other precipitation products can be seen around the observed rainfall variation. The same pattern can be seen for 640122 and 640150 stations: however, with CCS and CMORPH precipitation products. The patterns of 3B42-RT and CMORPH in 640112 are merely the same with patterns of CCS and CMORPH in 640122 and 640150 stations; however, the numerical values are different from each other. In addition,  
Figure 4: Annual and monthly rainfall of different precipitation products. (**a**) For station 640112; (**b**) For station 640122; (**c**) For station 640150.  
these underestimations can be clearly seen in monthly precipitation variations. Therefore, the underestimations demonstrated by 3B42-RT, CCS, and CMORPH depict that they are incapable of simulating high rainfall events that occurred during the rainy season. Interestingly, the precipitation products other than CCS and CMORPH, overestimated the observed rainfall. Nevertheless, while considering the highly variable nature of rainfall, these precipitation products can be used for hydrological analysis.  
A previous study by [PERSON] et al. [36] showed that 3B42 and IMERG over-estimates RG measured rainfall over the Chi River Basin of the north-eastern part of Thailand. The results are somewhat similar to the results obtained in the present study. Overall, it can be observed that with over-estimations and underestimations, the different precipitation products can still capture the rainfall pattern of the area.  
In previous studies in the tropical humid Ethiopia the CMORPH product has also demonstrated significant underestimates [60]. The reason for this is that CMORPH precipitation estimates are derived from the microwave data exclusively. In addition to CMORPH, the CCS has also demonstrated significant underestimates over the tropical humid regions. Both observations might be due to the difficulty in detecting rainfall over the comparatively shallow convective clouds. In another study, it has been demonstrated that CMORPH has demonstrated underestimates rainfall in the Upper Haihe River Basin which has a transitional area of the humid zone to the semi-arid zone [61]. [PERSON] et al. [62] also obtained underestimates of CMORPH rainfall over the middle part of the Haihe River Basin. The performance of CMORPH from previous studies clearly depicts that CMORPH under-estimate RG measured rainfall over the tropical humid climatic zones.