IALC Peace Fellowship Report Summer 2000
Graduate Hydrologic Program
University of Nevada, Reno
Jordan Field Trip to Investigate the Potential to Conduct a Flood and
Paleoflood Study in the Dead Sea and Wadi Araba Basins
Why flood /paleoflood study in Jordan?
Jordan as well as the entire Middle East region suffers from lack of water. This is among the most limiting factors in the development and the rising standard of living in the diverse communities the region. In arid and semi-arid environment, large floods present the only hydrological processes that generate large volumes of water available for surface storage and ground water recharge. Understanding of flood frequency and magnitude in desert areas becomes vital when human expansion and development extends near the areas of potential floods. However, information about past floods (Paleoflood) can provide unprecedented data set that is essential to understand the real behavior of extreme events, their magnitude and frequency, and there relation to hydroclimatic variability and possible global climatic change House (1991).
This report presents preliminary results from a recently initiated field trip to Jordan between July 25 and August 22, 2000. The goal of this field trip was to investigate the potential to carry out a flood /paleoflood study in the Dead Sea and Wadi Araba basins.
Jordan: Location and Climate
The Hashemite Kingdom of Jordan is situated between latitudes 29° 30' and 33° 30' north, and longitudes 35° to 39° east. The total area of Jordan is (82,000 sq. km). The census of 1996 recorded a total population of approximately 4.5 million.
Jordan can be divided into four different geomorphic and climatic zones:
- Jordan Valley and Wadi Araha (Jordan Rift). It is a narrow, 660-km strip of land, ranging in elevation between 200 to 400 meters below sea level, extending from the lake of Tiberias in the north, and continue to the south through the Dead Sea, Wadi Araba and the Gulf of Aqaba in the far south.
- Highlands. A mountainous area adjacent to the Jordan Rift, known for its mountains which vary from 600 m to 1750 m asl.
- Eastern Hills. An area to the east of the highland, known for its relatively plain lands, with gradual slope to the east.
- The Badia (local term, applied for marginal desert, used in Jordan, Syria. and Iraq). An area that extends to the east of the kingdom, known for its vastness and dry climate.
There are noticeable seasonal temperature variations, with summer tending to be hot and dry and winters cool and wet. Mean annual maximum temperatures reach 35 C to 38 C. Temperatures can fall below zero degrees Celsius in winter. Annual mean temperature drop as low as 2 C to 9 C. When cold, continental air penetrates into the area, the temperature can drop as low as 1.6C. The highest and lowest recorded temperatures are 46.4 C and -12.0 C respectively.
Rainfall is subject to drastic fluctuations in place and season. The mean annual rainfall in Jordan varies from less than 50 mm/yr in the eastern Badia to more than 600 mm/yr over Ajloun Heights. Rainfall occurs mostly from November through May, with 80% of the annual precipitation coming between December and March.
Before starting the fieldwork, contact and coordination with Yarmouk University, Water Authority, and other elated department have been made to get the needed materials and clearance for fieldwork. Collection of topographic maps and aerial photos of the study area also have been made. Fieldwork logistics and transport have been prepared as well.
The intended goal of this visit was to survey the canyons within Dead Sea and Wadi Araba basins, but because of shortage of time we were able only to survey the major canyons in the Dead Sea basin.
Dead Sea Basin
Dead Sea basin is 8500 km2 in the Central west of Jordan.. It consists of three sub basins: the Northeast Dead Sea, Mojib and Hassa. Its network drains the eastern mountains (1000 m above sea level) into the Dead Sea (400 m below sea level). Mean annual rainfall ranges from 250 mm in the upper parts to 50 mm in the lower parts. Its terrain is composed of hard carbonate rocks (Upper Cretaceous) mainly in the upper parts, and sandstone rocks (Lower Cretaceous and Triassic) mainly in the lower parts. The topography of the area is highly affected by the Dead Sea Rift and it shows a general tilt to the west toward the Dead Sea. More than twelve major canyons in this basin, these canyons are oriented from east to west. The incision of these canyons in the lower parts is very high where the average of the channel depth ranges from 60 m to 80 m.
Eight out of twelve canyons were surveyed for the potential of flood/paleoflood study. Starting from the north East Side of the Dead Sea, the following canyons were surveyed: Wadi El-Mujib, Wadi Esh-Shuqeiq, Wadi Ibn Hammad, Wadi El Karak. Wadi Weida'a, Wadi Isal, Wadi Hudeira, and Wadi El-Hassa. Wadi is an Arabic term that means ephemeral stream.
Description of all canyons described in this report always starts from downstream the canyon mouth going upstream.
1. Wadi El-Mujib.
Wadi El-Mujib is a 6000 km2 catchment in the middle of the dead sea basin and is consideredm the largest canyon in the basin. The average annual rainfall on this watershed is about 200 mm in the upper parts to 50 mm in the lower parts. The base flow in this Wadi is estimated to be 1.5 m3/s.
Starting from downstream where Wadi El-Mujib flows into the Dead Sea, we hiked upstream about three kilometers till the confluence of Wadi El-Mujib with Wadi Hiedan. The lower part of Wadi El-Mujib is a bedrock channel with about 70-90 m depth and 15-25 m width dissected into hard sandstone rocks.
The surveyed part of this canyon contains numerous slack water deposits (SWD), especially at the mouth of tributaries, but also as over bank deposits. Other palaeostage indicators, mainly driftwood lines, are present as well.
[Several pages are excerpted from this extensive field report.]
Results and Evaluations
Wadi El-Mujib and Wadi El Hassa are the major canyons in the Dead Sea basin with relatively large drainage area, 6000 km2 and 2400 km respectively. Both canyons preserve recent and ancient flood deposits with good potential for detailed flood/paleoflood analysis. Also both of the canyons have bedrock channels with proper geometry for topographic survey for hydrological modeling. Also access to these canyons is relatively good.
Most of the small watershed canyons have either slack water deposits or high water marks of recent floods.
International Arid Land Consortium (IALC), generously sponsored a Field trip to Jordan which aimed to investigate the potential to conduct a flood/paleoflood study in the Dead sea basin. Also professor Yehouda Enzel from Hebrew University of Jerusalem, thankfully participated in financing this trip. Special thanks to Tamir Grodek and Judith Leckekh from Hebrew University of Jerusalem for their join and help during the field survey and for their fruitful discussion. Thanks also to my advisor Professor Stephen Wells for his join in the field and for his advice and fruitful discussion.