An integrated approach of ground and aerial observations in flash flood disaster investigations. The case of the 2017 Mandra flash flood in Greece

A Multi-Platform Hydrometeorological Analysis of the Flash Flood Event of 15 November 2017 in Attica, Greece

“…Diakakis et al [51] also proposed a semi-empirical method to estimate peak discharge values based on site detailed post-surveys of flood extent and impact, which resulted to wide ranges of peak discharge values (30-40% error based on their analysis) for Soures and Agia Aikaterini streams around the values produced by the KLEM model. The XPOLbased WRF-Hydro simulation is characterized by the minimum difference about 20-30% in the estimated discharge peak with respect to [51]. This difference may be attributed to the configuration of the hydrological models which is usually based on calibration procedures using measured Diakakis et al [51] estimated a peak discharge for Soures stream about 170 m 3 /s and for Agia Aikaterini stream about 140 m 3 /s, using the same XPOL radar rainfall data to force the kinematic local excess model (KLEM; more information in [51]).…”

“…The first precipitation dataset was based on the results of the atmospheric component of CHAOS, the second on X-band dual-polarization experimental ground radar estimations and the third on GMP/IMERG satellite estimations. Post-survey and remote sensing maps were used to compare the extension of the flood [49][50][51]. The rest of the manuscript is organized as follows:…”

Evaluation of Hydrological and Hydraulic Models Applied in Typical Mediterranean Ungauged Watersheds Using Post-Flash-Flood Measurements

“…There is a strong relation between the intense urbanization of the Mediterranean coastal watersheds and the increase of the flash flood risk [59]. Respectively, Diakakis et al [11] in their research on the causes of the flood of Mandra in 2017 (Greece) indicate the influence of human interference that concerns the total alternation of the main stream dimensions and flow paths. Additionally, Segura-Beltrán et al [13] analyzed the flash flood of the Girona River (Spain) in 2007 and found that some human-induced factors, such as artificially narrow stream width, walls, and roads, caused the overbank flow.…”

“…The results revealed that the proposed methodology could be a very useful tool to researchers and policy makers for flood risk assessment of higher accuracy and effectiveness in ungauged Mediterranean watersheds.Hydrology 2020, 7, 12 2 of 24 settlements with the tolerance of the state have led to the gradual trespass of torrents, the reduction of streambed width, and in some cases to their complete disappearance. Under these circumstances, the hydraulic characteristics of streams and floodplains have been altered dramatically and have resulted in the intensification of the flood phenomena [10][11][12][13]. The protective role of forests from flash flood generation is questionable, and according to previous research studies is very limited, indicating that forests have negligible effects on the reduction of peak discharge during extreme rainfall events [10,12,14,15].Over the past years, considerable efforts have been made to estimate flood risk and simulate flood events, using hydrological and hydraulic models [16][17][18][19][20][21][22][23].…”

“…Hydrology 2020, 7, 12 2 of 24 settlements with the tolerance of the state have led to the gradual trespass of torrents, the reduction of streambed width, and in some cases to their complete disappearance. Under these circumstances, the hydraulic characteristics of streams and floodplains have been altered dramatically and have resulted in the intensification of the flood phenomena [10][11][12][13]. The protective role of forests from flash flood generation is questionable, and according to previous research studies is very limited, indicating that forests have negligible effects on the reduction of peak discharge during extreme rainfall events [10,12,14,15].…”