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wheat and barely as seasonal crops, and olives as tree Crops. 
Next in importance are marginal areas of rainfed cultivation, 
where the rainfall is less than 200 mm. These areas are facing 
the 3 problem of uncontrolled ploughing of land, which causes 
land degradation and the disappearance of palatable plants for 
animals. The third type of cultivation is irrigation agriculture. 
The main areas for this activity lie in the northern and 
southeastern parts of the study area, where this type of 
agriculture has been implemented since the late 1960's. In 1970 
the extent of irrigated area was estimated to be 400 hectares 
(Khalaf, 1987). Multi-temporal satellite images were used to 
assess the expansion of irrigated areas from 1983 through 1997. 
3.2 Livestock 
Many farmers depend largely on livestock production for food, 
additional income and for energy needs. Livestock is the main 
livelihood for the nomadic population. In 1997 the head of 
livestock in Jordan was estimated to be 3.15 million, whereas in 
1961 it was estimated at 0.62 million head. These statistics 
clearly show the heavy Livestock Impact (LI) on range land, 
which supports 40% of total feed requirements. The marked 
reduction in forage productivity further illustrates the state of 
degradation of the native vegetation, for while forage 
productivity is estimated to be 100 kg Dry Matter (DM)/hectare 
in steppe grassland, it is about 450 kg DM/hectare in the reserve 
range land (Nesheeiwat, 1996). Production of forage depends 
strongly on amount of precipitation and grazing management. 
4. PHYSICAL AND NATURAL FACTORS AFFECTING 
DESERTIFICATION 
4.1 Climate 
The climate of study area can be classified as semi-arid to arid. 
A Mediterranean climate of cold, mild winters and hot, dry 
summers is experienced only by the highlands in western part of 
study area. The annual average wind speed is 2.3 m/s. Wind 
speeds increase to 3.2 m/s during April, though may reach 5.7 
m/s in the southeast part. The rainy season extends from 
October to April, with the peak of precipitation occurring in 
January and February. The heaviest rainfalls are on the 
highlands of the western part of the study area, which receive a 
steady annual average of 250 mm. The potential evaporation 
rates of the study area range from about 1277 mm/year in the 
west part to 3832 mm/year in the eastern part. 
4.2 Land use and vegetation cover 
Detecting changes in land use, and monitoring of vegetation are 
very important for assessing land degradation and providing 
information for scientific decision-making. Landsat TM images 
from 1989 and 1997 were used to analyze and produce a land 
use and vegetation cover map. Landsat TM images allowed the 
discrimination of land use/cover types described in Table 1. 
The Mafraq area is well known as a supplier of stone for 
building construction. In the area southwest of the city, there are 
numerous quarries, which have destroyed an important part of 
the range land area. Figure 2 shows the land use map created 
using satellite images of 1997. ' 
4.3 Soil erosion susceptibility 
Soil erosion is caused by removal of vegetation, deforestation, 
overgrazing, etc. Which in turn results in to pollution of 
IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India,2002 
   
physical, biotic and socioeconomic environment. All soils are 
susceptible to erosion either by wind or water. 
Table 1 statistical result of land use classification 
  
  
  
  
Classes Area hectares Percentage 
Orchards 1199 0.96 
Rainfed agriculture 6216 4.99 
Rainfed-marginal agriculture 35692 28.63 
Irrigated agriculture 7178 5.76 
Woodland & scrub 2991 2.40 
Reserved rangeland 2020 1.62 
Dense steppe grassland 39182. 31.43 
Rangeland 26636 21.36 
Urban area 2171 1.74 
Quarries area 1153 0.92 
Water bodies 238 0.19 
Total 124675 100.00 
  
  
A Geographic Information System (GIS) was employed to 
produce a water erosion susceptibility map. The preparation 
involved spatial integration of data on topography, soil types, 
drainage system and the land use map (CNT, 1992). This 
process classified water erosion susceptibility into four classes 
ranging from slight to very high susceptibility to erosion. 
Desert soils generally are highly susceptible to wind erosion. 
The marginal lands (central part of the study area) were exposed 
to uncontrolled plowing, causing excessive wind erosion. The 
data layers representing geomorphic units, soil types and 
rainfall, which were used to identify marginal lands, were 
combined via the GIS tools to provide a wind erosion 
susceptibility map. This map is also divided into four classes 
varying from slightly to very highly susceptible to wind erosion. 
5. DESERTIFICATION ASSESSMENT 
5.1 Desertification causes 
The following are considered to be the most important human 
causes of desertification in the study area: 
  
  
Figure 2 Land use map created by 
Landsat TM image of 1997