Introduction

The Hashemite Kingdom of Jordan is about 100 km from the south-eastern coast of the Mediterranean Sea, between latitudes 29º-33º N and longitudes 35º-39º E. It borders Syria to the North, Iraq to the east, Saudi Arabia on both eastern and southern borders, and Palestine to the west (see Figure 1), and has a land area of about 89 200 km2, of which arable land is less than five percent

Modified from: M. Abusetta Al-Jalaudy

Physical geography

There are four main physiographic regions:

1) Jordan Rift Valley and Wadi Araba. The rift valley extends from Lake Tiberias in the north to the Gulf of Aqaba in the south. It is the Jordanian part of a continental shelf extending from Aqaba in the South to the Adasiyyah in the North. This zone is divided into three areas:

- The Jordan Valley, lies between 200-400 m below sea level, extending from Lake Tiberias in the North to the Dead Sea, with a length of 104 km and a width of between 4-16 km; it is surrounded in the east and west by high mountains. Rainfall decreases from approximately 300 mm in the north to 102 mm in the South.

- The Southern Ghor, this also lies below sea level to the South of the Dead Sea. Annual rainfall is less than 100 mm.

- The Wadi Araba, this area extends between the Southern Ghor and Aqaba on the Red Sea. It is extremely dry, with limited cultivated areas using underground water. The Jordan Valley and the Southern Ghor are among the most important agricultural areas, as there is a permanent source of water from the Yarmouk River and side dams for the former, and from surface water for the latter. Due to their position below sea level and high temperatures (microclimate), these two are the most important winter vegetable producing areas.

2) The Highlands. These extend from the Yarmouk River in the north passing through the Ajloun mountains, the hills of Ammon and Moab, and the Edom mountains. Many creeks and wadis drain from the east to the Jordan River, Dead Sea, and Wadi Araba. The average altitude ranges from 600 m in the north to 1,000 m in the middle and 1,500 m in the south. The highlands, which are a succession of catchment and sub-catchments, comprise: a semi-arid zone (350-500 mm annual rainfall) and a small sub-humid zone (over 500 mm annual rainfall).

3) The Arid Zone (Plains). This comprises the plains between the Badia (semi desert) and the Highlands. Rainfall ranges between 200 mm in the East and 350 mm in the West. More than 50 percent of the arable land is in this zone, the rainfed crops are mainly barley (areas of 200-300 mm of rainfall) wheat and fruit trees (where rainfall ranges between 300 and 350 mm).

4) The Badia (Eastern Desert). This covers about 8 090 000 ha or 90 percent of the Kingdom. It is characterized by a very sparse vegetation cover and an annual rainfall of less than 200 mm. In the past it was only used for grazing. In the last two decades, however, 20 000 ha have been irrigated, using underground water, to grow vegetables (especially tomatoes, watermelon and potatoes), plus fruit trees and cereals, especially wheat.

The actual cultivated area in 1997 totaled around 290,000 ha, of which 130,000 are planted with olives and fruit trees, 50,000 with vegetables and 110000 with field crops. About 90 percent, or 80,771 km2, of the Kingdom is grazing land; 69,077 km2 of which receive under 100 mm of rainfall, and 1 000 km2 of marginal grazing with 100-200 mm annual rainfall. Natural and man-made forests cover 760 km2, out of 1,300 km2 registered as forests. There are also about 500 km2 of state-owned land used for grazing in mountainous areas.

Modified from: Jordan Country Study on Biological Diversity, 1998

Climate

Jordan is on the eastern margins of the Mediterranean climatic zone of the eastern Mediterranean. This climate is characterized by hot, dry summers and cool, wet winters. More than 90 percent of the country receives less than 200 mm annual precipitation (precipitation map). There is a maximum annual rainfall of 600 mm in the north-west corner of the country. Average temperatures show a reverse pattern: they increase rapidly from the dissected plateaus to the very low level graben, increase gradually from the dissected plateau to the eastern margins of the eastern desert, and decrease gradually from north to south in line with increasing altitude. The highest annual and monthly values for evapotranspiration are in the desert with an annual total of 2,427 mm for Ma´an and 2,325 mm for Rweishid in the northeast. In the highlands, values vary from 1,485 mm at Rabba to 1,343 mm at Shoubak.
Highest monthly precipitation values occur in July and the lowest in January for all the country.

Bioclimatic zones

There are four bioclimatic subdivisions in Jordan (Long, 1957):

1) Mediterranean. This region is restricted to the highlands extending from Irbid in the north to Ras En-Naqab in the south. The altitude ranges from 700-1750 m above sea level. The rainfall ranges from 300-600 mm. The minimum annual temperature ranges from 5-10 ºC. Soil type is dominated by the red Mediterranean soil (terra rosa) and the yellow Mediterranean soil (rendzina). This region comprises the most fertile part of the Kingdom and contains 90 percent of the population.

2) Irano-Turanian. A narrow strip of variable width that surrounds all the Mediterranean ecozone except in the north. It is characterized by being treeless. The vegetation is mainly small shrubs and bushes such as Artemisia herba-alba,and Anabasis syriaca. Altitudes range from 500-700 m, and rainfall ranges from 150-300 mm. Mean annual minimum temperatures range from 5-2 ºC, and mean annual maxima range from 15-25 ºC. Soils are mostly calcareous or transported by wind. The vegetation is dominated by chamaeophytes.

3) Saharo-Arabian. This is the eastern desert or Badia and comprises the largest part of Jordan encompassing almost 80% of its total area. It is flat except for a few hills or small mountains, the result of volcanic eruptions. Altitude ranges between 500-700 m. The mean annual rainfall ranges from 50-200 mm, mean annual minimum temperatures range from 15-2 ºC. Soil is mostly poor, either clay, hammada, saline, sandy or calcareous. Vegetation is dominated by small shrubs and small annuals in the wadi beds.

4) Sudanian. : It starts from the northern part of the Dead Sea and ends at the tip of the Gulf of Aqaba in the south along the Dead Sea depression and Wadi Araba. The most important characteristic of this region is the altitude, considered the lowest point on earth (396 m below sea level near the Dead Sea). Rainfall ranges from 50-100 mm, the mean annual minimum temperature ranges from 10-29 ºC, and mean annual maximum temperatures range from the minimal 20 to 35 ºC. Soils are mostly alluvial, saline, sandy and granitic. The only inland sand dunes are in this region. The vegetation is characterized by a tropical tree element such as Acacia sp. and Ziziphus spina-christi in addition to some shrubs and annual herbs.