Large wood and flash floods: Evidence from the 2007 event in the Davča basin (Slovenia)

Abstract

This paper presents the evidence gathered during a post-flood survey in a Slovenian mountain basin (Dava basin, drainage area of 32 km) following the catastrophic flood of September 2007. Channel avulsion, debris flows and landslides delivered large volumes of wood into the channel, and massive wood accumulations were found at the basin outlet. Wood-induced dam-break flows were therefore hypothesised to be responsible for most of the damages. Field observations and approximate discharge estimations indicate that the damages suffered in the Dava basin can be attributed to excessive wood load only to a limited extent, and that the critical factors were narrow road crossings which acted as traps for sediment and wood.