EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

The signature of extreme rainstorms properties on cliff morphology in arid areas 

Yuval Shmilovitz1, Francesco Marra2, Yehouda Enzel1, Efrat Morin1, Moshe Armon1,3, Ari Matmon1, Amit Mushkin4, Yoav Levi5, Pavel Khain5, and Itai Haviv6
Yuval Shmilovitz et al.
  • 1The Hebrew University of Jerusalem, The Fredy & Nadine Herrmann Institute of Earth Sciences, Jerusalem, Israel (
  • 2National Research Council of Italy, Institute of Atmospheric Sciences and Climate (CNR-ISAC), Bologna, Italy
  • 3Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • 4Geological Survey of Israel, 32 Yesha'ayahu Leibowitz, Jerusalem 9692100, Israel
  • 5Israel Meteorological Service, Beit Dagan, 5025001, Israel
  • 6Department of Earth and Environmental Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

Climatic impact on landscape morphology was previously demonstrated under pronounced gradients in average climatic properties such as mean annual precipitation or temperature. However, in arid areas, where both meteorological observations and rainfall measurements are scarce and the latter is meager, short-term and highly variable in space and time, the determination of meaningful “average climatic” conditions and their variability is challenging. Although it is generally acknowledged that surface processes in arid landscapes should be effected by short-duration rainfall intensities and their extremes, the topographic sensitivity to storm-scale properties were rarely quantified. Here, we attempted to bridge this gap by documenting systematic precipitation variations along a 40 km arid escarpment (Ramon crater) in the central Negev desert (Israel) and their associated topographic signature.

We used 0.5 m pixel-1 LiDAR-derived topographic data coupled with field measurements to characterize the morphology of cliffs and slopes along the entire Ramon crater. Sub-hourly rainfall intensities were characterized using an 8-year record of high-resolution, convection-permitting, numerical weather model prediction (NWP). Frequency analyses of rainfall intensity and its spatial variation were conducted using a novel statistical method and used to determine runoff and sediment transport along sub-cliff slopes, through grid-based hydrological simulations of synthetic rainstorms with different frequencies.

Our results indicate that due to a pronounced decreasing gradient in the number of rain storms per year, the mean annual rainfall decreases from ~100 mm in the southwest (SW) cliff segment to ~40 mm in the northeast (NE) segment. However, in the drier NE cliff segment, extreme rainfall intensities such as the ones occurring during a storm with a 100-year return period are higher. Topographic cliff gradients and the percentage of exposed bedrock over the cliffs increase toward the drier NE cliff section. Sub-cliff slopes in the NE are systematically straighter, shorter, and associated with a smaller clast sizes relative to the wetter (SW) part of the escarpment. Hydrological simulations reveal that under extreme storms, sediment is mobilized by sheetwash on the NE slopes but is less mobile on the wetter SW slopes. In addition, incised gullies and disconnected talus-flatirons are more frequent in the NE and correlate with the higher erosion efficiency of extreme rainstorms in this zone. Our results indicate that significant morphologic differences can be imprinted in arid landforms due to spatial gradients in the properties of extreme rainstorms.  

How to cite: Shmilovitz, Y., Marra, F., Enzel, Y., Morin, E., Armon, M., Matmon, A., Mushkin, A., Levi, Y., Khain, P., and Haviv, I.: The signature of extreme rainstorms properties on cliff morphology in arid areas , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4061,, 2022.