Reply on RC1

Abstract

In arid regions, debris flows are occasionally observed when torrential rainfall hits steep slopes with unconsolidated materials. Despite the important related hazards, not much is yet known about the critical rainfall conditions for debris flow initiation in dryland areas. In this study, we use high-resolution digital surface models and weather radar rainfall estimates for the detection and characterization of triggering and non-triggering storms. We focus on the arid slopes of the Dead Sea north-western margins and use the differences of digital surface models to identify deposits from over 40, relatively small, short-lived debris flows (SLDFs) occurred between 2013 and 2019. We divide them into four groups based on their spatial distribution and triggering period, and identify the most likely triggering storm for each group. Using high-resolution weather radar data we show that the SLDFs were likely initiated by an intense convective cell (lasting 20 to 45 min) which was preceded by significant rainfall amounts (8–12 mm) delivered during the storm. Comparing triggering and non-triggering storms, we observed that rain intensity alone is insufficient to explain the phenomena, and discuss the possibility that antecedent rainfall could represent a critical factor for the triggering of SLDFs in steep slopes of arid environments.