Analysis of a Flash Flood in a Small Basin in Crete

Abstract

Climate change will have a greater impact on the severity of flash floods, since precipitation intensity is expected to increase, even in areas where a reduction of precipitation is possible. This change in climate is expected to increase flood wave speed and its flood wave area extent. A case study of a small basin in the island of Crete was conducted to examine this effect, following the calibration and validation of the flow hydrograph of a flash flood event, in order to achieve model verification with the post-flood data. It was found that the most important parameters that affect the timing and magnitude of the peak discharge are the storage coefficient, the impervious rate and the curve number, as well as the time of concentration. Rainfall distribution was examined in different time intervals in order to study the effect of the intensity of precipitation on the peak hydrograph. From the precipitation records and according to the size of the watershed, the time step of the precipitation in the simulation model is recommended to be less than an hour. In other areas around the basin of interest, severe storms known as Medicanes that pass over Crete can produce higher precipitation in shorter time intervals. The impact of climate change scenarios results in an increase on the peak discharge by creating precipitation of higher intensity. Furthermore, the intensification of precipitation due to climate change results in higher flood depths and flooded area extent, as well as wave velocities.

Earth Observation Data Synergy for the Enhanced Monitoring of Ephemeral Water Bodies to Anticipate Karst-Related Flooding

“…The recharge zones are located in a well developed epikarst zone characterized by high permeability underlying a shallow unconfined aquifer [51]. Examples of similar karst wetlands characterized by ephemeral inundations have been reported in Wales, Slovenia, Spain, Italy, Greece, Ireland, and Canada [7,[52][53][54][55][56][57][58][59][60].…”

Flood Peaks and Geomorphic Processes in an Ephemeral Mediterranean Stream: Torrent de Sant Jordi (Pollença, Mallorca)

“…In 2022 alone, 387 disasters were identified, with 176 being floods causing over 30,000 fatalities and billions in economic losses [2]. While major floods are the main cause of fatalities and damage, there are also other types of events that are comparatively smaller but not less damaging [3,4]. Climate change trends increases the expected impact of flood episodes as the frequency and severity of their occurrence grows exponentially but unevenly, as the spatiotemporal variation of floods, regarding frequency and magnitude, may increase in some areas, while in other places it may decrease [5,6].…”