World’s Soil Resources

Figure 13.4 Rate of water erosion in Iran. Source: Soil Conservation and Watershed Management Research Institute.
Water erosion
In Iran about 40 percent of the country experiences a low erosion rate (less than 10 tonnes ha -1 ), 25 percent
of the area has a moderate rate of water erosion (10 to 20 tonnes ha -1 ), 23 percent area of the country has a
high erosion rate (20 to 50 tonnes ha -1 ), and 12 percent has a very high erosion (more than 50 tonnes ha -1 ).
Figure 13.4 shows the erosion rates in different regions of Iran.
Results of recent research conducted in the watersheds of the country in recentyears suggest an increased
rate of erosion according to various models used (Hosseinkhani, 2013; Kavian et al., 2014; Karam, Safarian
and Hajjeh Froshnia, 2010; Zomorodian and Rahimi, 2012; Bayat et al., 2011; Naderi, Karimi and Naseri, 2010;
Zare Bidaki and Badri, 2014). Land-use change is one of the most important factors that exacerbate erosion in
basins (Mohamadzade, Charm and Eskandari, 2014; Ajami, Khormali and Ayoubi, 2012).
Wind erosion
In Iran’s deserts and arid areas, rapid changes in temperature cause pressure gradients in different parts
which result in constant strong winds. Due to these strong winds and to the lack of moisture and vegetation,
both small and large soil particles are transported, leading to soil erosion and deposition (Mehrshahy and
Nakoonam, 2009). Sand dunes are estimated to cover 12 million ha. Half of these dunes are active or semiactive
(Refahi, 2004). The density of air deposits measured over a 40year period shows a growing trend in
wind erosion in recent years. Sediment textures have also changed, with a significant increase in evaporated
deposits such as salts and gypsum.
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in the Near East and North Africa