*3.2. Mean, Minimum and Maximum Basin Precipitation*

In order to compare the performances of the precipitation products in each individual basin within the three flood events that occurred from March to April 2019, the mean, minimum, and maximum precipitations were plotted, as shown in Figure 7. The first flood event occurred in the Gorganrud Basin in northeastern Iran. As Figure 7a shows, in terms of mean, maximum, and minimum precipitation, the ECMWF and UKMO models performed approximately the same and well forecasted the min, max, and mean of precipitation. The NCEP model also forecasted less precipitation than the observations with respect to mean precipitation. However, the maximum in situ observations in this basin was higher than all the NWP and IMERG satellite products. Although all evaluated precipitation products were rather close to the in situ measurements, it is evident that ECMWF and UKMO, followed by IMERG, compared well with the corresponding in situ measurements in terms of mean precipitation through the first event.

Figure 7b shows the mean, min, and max value of precipitation obtained from all products and in situ observations over the southwest of Iran within the Karkheh and Karun Basins. The mean precipitation values indicated that generally all of the models and satellite well estimated the mean areal precipitation with a slight underestimation during this event over the Karkheh Basin. However, in terms of maximum precipitation, the UKMO overestimated, while the satellite and other models showed underestimation over the Karkheh Basin during the second flood event. This might be due to high moisture in the atmosphere and the occurrence of small scale precipitation systems that were dominant during this event [23]. Additionally, from the median and the 25th and 75th percentiles of the box-plots, one can infer that the precipitation estimated by IMERG, followed by ECMWF, was more accurate than the other products in both basins, while the UKMO whiskers extended to the highest extreme data points in comparison to the other products.

According to Figure 7c, the mean areal precipitation values of all products were rather close to the in situ observations over the Karkheh Basin, while the box-plots confirmed that the IMERG and NCEP values were in a larger and smaller precipitation ranges in comparison to the in situ observations, respectively. However, in the Karun Basin, the UKMO greatly overestimated the precipitation, while IMERG, followed by NCEP, showed improvement in heavy daily precipitation in comparison with the in situ observations.

**Figure 7.** Mean, maximum, minimum precipitation amounts and box-plots in the (**a**) Gorganrud, Karkheh, and Karun Basins for the a) first, (**b**) second, and (**c**) third flood events. The center-line of each boxplot depicts the median value (50th percentile) and the box encompasses the 25th and 75th percentiles of the sample data, while the whiskers represent the extreme values, respectively.
