Preprints
https://doi.org/10.5194/nhess-2022-184
https://doi.org/10.5194/nhess-2022-184
 
20 Jul 2022
20 Jul 2022
Status: this preprint is currently under review for the journal NHESS.

Antecedent rainfall as a critical factor for the triggering of short-lived debris flows in arid regions

Shalev Siman-Tov1 and Francesco Marra2 Shalev Siman-Tov and Francesco Marra
  • 1Geological Hazards Division, Geological Survey of Israel, Jerusalem, 9692100, Israel
  • 2Institute of Atmospheric Sciences and Climate, National Research Council, Bologna, Italy

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.

Shalev Siman-Tov and Francesco Marra

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2022-184', Anonymous Referee #1, 18 Aug 2022
    • AC1: 'Reply on RC1', Shalev Siman-Tov, 12 Oct 2022
  • RC2: 'Comment on nhess-2022-184', Anonymous Referee #2, 22 Aug 2022
    • AC2: 'Reply on RC2', Shalev Siman-Tov, 12 Oct 2022

Shalev Siman-Tov and Francesco Marra

Shalev Siman-Tov and Francesco Marra

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Short summary
Debris flows represent a threat to infrastructures and population. In arid areas, they are observed when heavy rainfall hits steep slopes with sediments. Here, we use digital surface models and radar rainfall data to detect and characterize the triggering and non-triggering rainfall conditions. We find that rainfall intensity alone is insufficient to explain the triggering. We suggest that antecedent rainfall could represent a critical factor for debris flow triggering in arid regions.
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