## 4 Conclusions  
SPPs are important precipitation data alternatives, particularly in high mountain watersheds, where measurement gauge stations are poorly distributed or absent. These products will mainly help in the simulation of river flows, flood forecasting, and water resources management in arid to semi-arid regions. This study conducted a complete performance evaluation of two satellite products--the TRMM (3B42 V7) and the GPM--(IMERG V05) using observations (sub-hourly, daily, monthly, and yearly) collected from the only gauge station of the Zat basin, named Taferiat station, and located at the downstream of the watershed. The watershed is characterized by a Mediterranean climate and mountainous topography, and the study was analyzed over 3 years, from 1 September 2014 to 31 August 2017. To evaluate the accuracy of 3B42 V7 and IMERG V05 satellite precipitation products, several quantitative, categorical, and statistical measurements were used: (R, RMSE, Bias) were used to quantitatively analyzed the accuracy of satellite precipitation products, and (POD, CSI, FAR, and FBI) were used to evaluate the precipitation detection capability of satellite precipitation products, and to simulate satisfactorily the flooding events in hydrological model. The conclusions resulting from this study are summarized as follows:  
1. 3B42 V7 and IMERG V05 products performed well in estimating sub-hourly, daily, monthly, and annual precipitation compared to observed data from the Taferiat station. 3B42V7 underestimated low precipitation events but well estimated heavy precipitation with small time step. However, the monthly and annual precipitation were well captured. While IMERGYV05 overestimates heavy precipitation episodes and has a good ability to detect low precipitation in small time step, the monthly and the yearly precipitation are well estimated by this product. Figure 9: Validation of the episode of 16 December 2016, of 3B42V7 and IMERG V05 rainfall products and observed runoff data as input using the means calibration parameters of the gauge precipitation calibration. 2. Compared to the ground applications, 3B42V7 and IMERG V5 showed acceptable correlation results at the sub-hourly and daily time scales. However, IMERG V05 performed slightly better than 3B42 V7 for the detection of sub-hourly and daily precipitation at the measuring station. The categorical statistical measures values showed high values of POD and CSI, as well as reasonably high values of FAR and FBI, noting that the results of the categorical measures are good. In general, IMERG V05 is better at detecting precipitation events, in particular at capturing precipitation traces and solid precipitation at a 3-hourly and daily scale, while 3B42 V7 can estimate precipitation on a large time scale. 3. The hydrological calibration and validation were performed according to two different scenarios; scenario 1 aims to simulate and calibrate events using rainfall from both satellite products with observed flows, while scenario 2 of validation uses the leave-one-out resampling approach; for the n flood events, in order to find the relationship between the root-soil moisture measured and the most sensitive model parameters (CN calibration, and time of concentration \"TC\"). The obtained results are satisfactory for all calibration and validation parts, the NSE coefficients ranging between 74.75% and 63.31%, respectively. The main point to remember is that the 3B42V7 product does not have a good ability to capture small rainfall events in a short time step, in fact, it underestimates the rainfall. On the other hand, the IMERG V05 product has an excellent capacity to record small rainfall events, which is well demonstrated in the validation graphs. Therefore, it is recommended to use this product for flood modeling and forecasting. The proposed method is an interesting approach to apply for solving the problem of insufficient observed data in the Mediterranean regions.