# Hydrological Analysis of Extreme Rain Events in a Medium-Sized Basin
## 5 Conclusions
The peak hydrograph of W1460 was also better approached with the HBV-light model, despite the HEC-HMS model producing a more effective NSE coefficient. In the event of 7-15 April 2013, the total rainfall was less than the corresponding of the 30 April-7 May 2017 event, and at the same time, the intensity of the rain was higher during the second hydrological peak and not during the first. For these reasons, we believe that the warm-up period of the HBV-light model was crucial for achieving an obviously better fit of the flow hydrographs of the sub-basins than with the HEC-HMS model. Specifically, all sub-basins showed better indices by using the HBV-light model, except for the W790 sub-basin in which the volume error index was slightly raised in comparison to the one resulting from the HEC-HMS model. Apart from that, a few low temperatures for a certain period indicated that the precipitated water for the particular time was modeled as snow, which was also a significant factor showing that HBV-light performed better. On the other hand, the high-intensity 4-10 July 2013 event, having at the same time very high total water volume in each of the studied sub-basins, was fitted more appropriately with the HEC-HMS model. Both rural sub-basins, as well as W800, produced better indices via the HEC-HMS; however, W900 was better fitted through the HBV-light. The urban sub-basin had a better Nash-Sutcliffe index with the HBV-light model, thus a decreased volume error-index with the HEC-HMS. The volume error-index was notably decreased with the HEC-HMS model also in the W1020 sub-basin, with both models producing similar Nash-Sutcliffe index. Therefore, in general, the HEC-HMS model performed better for the higher intensity event. In the 30 April-7 May 2017 event, the total rain was higher than the relevant 7-15 April 2013 event, but with lower values of the corresponding maximum precipitation intensities. When comparing the two hydrological peaks of the 30 April-7 May 2017 event, the rain intensity was higher during the first hydrological peak rather than the second. Regarding the rural sub-basins (W1460, W790) and the rural with fairly or some urban development (W800, W900), respectively, the sub-basins with similar land uses but with smaller areas (W790, W900) fitted better with the HEC-HMS model, whereas the corresponding bigger areal extent (W1460, W800) matched more appropriately with the HBV-light model. The urban sub-basin produced a more satisfactory Nash-Sutcliffe index with the HBV-light model, but a rather higher volume index error; the volume index error was more satisfied with the HEC-HMS model. On the other hand, the semi-urban and semi-rural sub-basin in which the sub-basins W1460, W790, W800, and W900 also outflow resulted in a better fit of both indices by using the HBV-light model. The overall result was that both models performed similarly well. The 22-25 June 2017 event which was of higher total precipitation volume, higher maximum precipitation intensity in most of the sub-basins (W1460, W790, W800, W900), but of shorter duration, compared with the relevant 26-30 June 2010 event, produced more fitted examined indices with the HEC-HMS model concerning the W790 and W900 sub-basin. Concerning the W1460 and W790, the Nash-Sutcliffe indices were higher with the HBV-light model, but the volume error indices were lower with the HEC-HMS model. The urban sub-basin produced better Nash-Sutcliffe also with the HBV-light model, but the volume error-index was lower with the HEC-HMS model too, however, with the peak hydrograph fitting better with the HBV-light model. The W1020 sub-basin produced a more appropriate NSE coefficient with the HBV-light model, but the volume error-index was slightly raised in comparison with the HEC-HMS model. Therefore, the approach of both models was rather satisfactory, and neither model was distinguished from the other.