Fjölrit RALA - 05.12.1999, Blaðsíða 78

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Desertification in Ethiopian highlands
are susceptible and prone to desertification processes as defined by the UN: “land deg-
radation in arid, semi-arid and dry sub-humid areas resulting from various factors, in-
cluding climatic variations and human activities” (UN CCD 1994).
Table 1. Data on rainfall, evapo-transpiration, and aridity index for 250 stations in Ethiopia.
No. of stations - Eievation, m Rainfall, mm/yr Evapo- transpiration mm/yr Aridity index Land area
Zone (Total=250) Range Mean Range Mean Range Mean Range Mean km2xiooo
Humid (moist) 138 425-3000 2205 910-2448 1679 1043-1681 1362 0.67-1,83 1.25 350
Dry sub-humid 37 1200-2700 2000 642-1117 900 1312-1790 1510 0.50-0.65 0.596 300
Semi-arid 50 625-2550 1639 411-897 656 1284-2138 1700 0.2-0.50 0.377 207
Arid 20 175-1000 510 83-406 266 1630-2950 2213 0.05-0.2 0.124 300
Hyper-arid 5 0-660 300 28-113 70 2830-2832 2831 <0.05 0.025 53
i
i
Figure 1. Dryland areas in Ethiopia delineated on the bases of RR/PET
ratio. (Based on the information from NMSA, FAO and de Pauw).
Legend:
Hyper-arid
Arid
Semi-arid
Dry sub-humid
Humid
= RR/PET<0.02
= 0.02<RR/PET<0.20
= 0.20<RR/PET<0.50
= 0.5<RR/PET<0.65
= RR/PET>0.65
EXTENT OF LAND DEGRADATION 1N ETHIOPIA
The Ethiopian highland studies revealed that the Ethiopian highlands, which cover
44% of the country’s total land area are seriously threatened by soil and biological
degradation. Some 27 million ha representing approximately 50% of the highlands are