Floods are among the most dangerous natural hazards affecting the development of an area. In Greece, many drainage basins are relatively small with steep slopes, configured by steep streams with braided main channel morphology. These systems are usually dry, but experience extreme flash flood events of low frequency, but high magnitude. Such exceptionally high runoff may be a source of significant damage to human infrastructure. Despite the importance of these floods, the hydrological analysis of ephemeral streams in Greece has been especially difficult due to the lack of discharge gauges.
The aim of this study is to present a flood hazard assessment and mapping methodology for the Kerinitis River drainage basin which is located in the North Peloponnese. Additionally, the simulation of a flash flood event along the main channel of the river caused by an extreme rainfall event, similar to the storm that took place on January 11th and 12th, 1997 above the nearby catchment of Xerias River, using a surface GIS-based runoff model was attempted. The application of this modeling led to the direct runoff hydrograph along the Kerinitis main channel at the outlet of the basin (the apex of the fan-delta). The proposed methodologies are based on the application of GIS with the integration of various data concerning the study area.