A high magnitude storm and flood in a hyperarid catchment, Nahal Zin, Negev Desert, Israel

Noam Greenbaum, Adina Margalit, Asher P. Schick, David Sharon, Victor Baker

Research output: Contribution to journalArticle

79 Citations (Scopus)

Abstract

In October 1991 a high magnitude rainstorm flood, estimated return period 40 years, occurred in Nahal Zin, a 1400 km2 catchment in the hyperarid Negev Desert. The meso-scale structure of the storm was a curved squall line that developed from a thunderstorm in accordance with the topography of the catchment divide, by which it was strongly affected. Tropical moisture reached the area via the subtropical jet stream, in conjunction with a lower level northward intrusion of the Red Sea trough (RST-N) into the Mediterranean Sea. Rainfall, as measured at the few and sparse gauging stations, was much too small to account for the resulting large flood. Peak flow and other hydraulic characteristics of the flood were indirectly reconstructed. The techniques of palaeoflood hydrology used were based on sedimentological evidence of fine-grained flood sediments deposited in back-flooded tributaries, as well as on other stage indicators. The HEC-2 procedure was employed to determine water surface profiles. The spatial and temporal characteristics of the event were studied through a combination of rainstorm analysis, remote sensing, hydrological and sedimentological data; they jointly explain the magnitude and timing of tributary contributions producing the integrated flood in the main channel. The flood as reconstructed reveals a three-peak hydrograph: two peaks were generated by the same storm but had different floodwave arrival times in the main channel; the third resulted from a local rainstorm which occurred on the following day and covered only one tributary. The curved structure of the storm and its dynamics in relation to catchment orientation resulted in storm movement in tandem with the floodwave. The synchronous contribution from all main tributaries preserved evidence of the floodwave both in stage and volume by replacing the transmission losses in the sections with thick alluvium. Other high magnitude floods on record for the large Negev Desert catchments are caused by a cold upper air incursion associated with the RST-N. Most of them occur in the autumn and are caused by storms with high-intensity rainfall. This is in stark contrast with the flooding behaviour of the semi-arid zone further north, which is linked primarily to the core of the Mediterranean winter. The complexities involved in the generation of a large desert flood, as revealed by this study, illustrate the fallacy of applying routine hydrological modelling to such events, and underline the need to study the processes involved in adequate detail.

Original languageEnglish (US)
Pages (from-to)1-23
Number of pages23
JournalHydrological Processes
Volume12
Issue number1
StatePublished - Jan 1998

Fingerprint

desert
catchment
tributary
rainstorm
paleoflood
transmission loss
squall line
jet stream
hydrological modeling
peak flow
return period
arrival time
thunderstorm
precipitation intensity
hydrograph
alluvial deposit
trough
hydrology
flooding
autumn

Keywords

  • Catchment runoff
  • Desert floods
  • Negev Desert
  • Palaeofloods
  • Red Sea trough
  • Slack water deposits
  • Squall line

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

A high magnitude storm and flood in a hyperarid catchment, Nahal Zin, Negev Desert, Israel. / Greenbaum, Noam; Margalit, Adina; Schick, Asher P.; Sharon, David; Baker, Victor.

In: Hydrological Processes, Vol. 12, No. 1, 01.1998, p. 1-23.

Research output: Contribution to journalArticle

Greenbaum, N, Margalit, A, Schick, AP, Sharon, D & Baker, V 1998, 'A high magnitude storm and flood in a hyperarid catchment, Nahal Zin, Negev Desert, Israel', Hydrological Processes, vol. 12, no. 1, pp. 1-23.
Greenbaum, Noam ; Margalit, Adina ; Schick, Asher P. ; Sharon, David ; Baker, Victor. / A high magnitude storm and flood in a hyperarid catchment, Nahal Zin, Negev Desert, Israel. In: Hydrological Processes. 1998 ; Vol. 12, No. 1. pp. 1-23.
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