International Arid Lands Consortium Supports Improved Forecasting and Measurement of Major Flash Flooding in Arid Regions

Research leads to runoff control measures that can save lives and reduce property damage.

November 30, 2000 (Tucson, AZ)--In arid areas, flash floods constitute the majority of casualties of all natural hazards. Most cases result from localized convective showers, which are common in the Middle-East, and contribute up to 25% of the annual Negev rainfall in the form of high intensity rains. The occurrence of such rainstorms is mostly associated with tropical intrusions extending from eastern Africa toward the Middle-East.

The International Arid Lands Consortium (IALC) is supporting scientists from the Hebrew University of Jerusalem, the Open University of Israel, and the University of Arizona, who are involved in a two-year study entitled "Structure and Dynamics of Rainstorms Inducing Floods in the Negev."

The purpose of the research is to improve knowledge of what happens during floods, including the structure of weather patterns and local surface features affecting how the flood occurs in space and in time. The research sheds new light on the physical linkage between rainfall elements and the type of resulting flash floods, and how the floods are affected by the land features and catchments, or places where water collects after a rainfall.

After completing, augmenting and updating a comprehensive data base of floods in the Negev and the related conditions, and detailed analysis of selected events that induced extreme floods, researchers are attempting to define the atmospheric conditions that are favorable for occurrence of major floods. The investigation includes a systematic comparison of individual storms and recurring patterns that may allow for improved measures of control.

Researchers seek new insights on the physical relationship between certain types of rainfall systems and the conditions and moisture sources under which they developed, and local effects of abrupt topographic features, land/sea differences and other elements that make flash flooding more likely. This research contributes to the management of arid ecological systems by improving the forecasting of the potential for major flooding, and identification of the most susceptible regions. This may enable taking precautions that can save lives and prevent property damage.

In another two-year study, entitled "Radar Scaling and Runoff Prediction Models in Arid and Semi Arid Basins," two departments from the University of Arizona are cooperating to analyze new types of rainfall data to predict runoff in arid and semiarid basins in Israel and Arizona.

The lack of rainfall data, which is crucial for hydrological modeling, is one of the most serious problems confronting arid hydrological modelers. Now, when meteorological radar systems cover arid and semiarid regions and high-resolution rainfall data are available, new opportunities exist.

Radar rainfall data are essentially different from the rain gauge data in their unit area, spatial coverage and data accuracy; therefore, the radar data should be viewed as new type of rainfall data. New approaches of rainfall-runoff analysis using radar data are needed.

Researchers seek to discover the most appropriate scale to represent radar rainfall for runoff prediction. Although rainfall is highly variable in space and time, outlet runoff, which is the result of rainfall that exceeds that which can be soaked up by the ground, is not necessarily sensitive to the small scale variation. Several factors must be considered in establishing appropriate scales with which to make measurements, so that important data is not overlooked.

The implications of this research are in runoff prediction, flood control, water harvesting, road constructions, and other control measures to prevent loss of life and property damage.

Support for these projects came from the USDA Cooperative State Research, Education, and Extension Service, and the USDA Forest Service.



The International Arid Lands Consortium (IALC) is an independent nonprofit organization dedicated to exploring the problems and solutions unique to arid and semiarid regions. IALC promotes cooperative research and practical application of new knowledge to develop sustainable ecological practices. The member institutions and their affiliates share a mission to enable people of arid lands to improve the quality of life for future generations. IALC members include the University of Arizona, Desert Research Institute-Nevada, the University of Illinois, Jewish National Fund, New Mexico State University, South Dakota State University, Texas A&M University-Kingsville, and the Higher Council for Science & Technology-Jordan. The Ministry of Agriculture & Land Reclamation-Egypt is an affiliate member.

Project Addressed in this News Release:
  • 00R-11 Radar Scaling and Runoff Prediction Models in Arid and Semi-Arid Basins (The University of Arizona)

  • 00R-21 Structure and Dynamics of Rainstorms Inducing Floods in the Negev (The Hebrew University of Jerusalem, The University of Arizona, The Open University of Israel)