مهار بيابان‌زايي

1.                       History of drought and desertification control

   in Ancient Iran:

   Reviewing the history of Iran, one comes across with recognitions and experiences of Iranians regarding drought and desertification that will be explained briefly:

1.1.                 Examples of doctrines

   Based on archeological studies and evidences, Iranians seemed to be familiar with soil degrading factors and attempted to control them. For example, approximately 3000 years ago, the ancient Iranians (Aryans) introduced aqueducts, a proper, sustainable and low cost technique for exploitation of invisible underground water, to the world which boosted their resistance to water shortage during dry seasons and droughts. Even earlier, the North Eastern habitats of Iran had probably found that building dams not only improved their agricultural practices but also recharged the underground waters by irrigation of alluvial fans, as a result of which the signs of desertification was postponed. Therefore, these two coordinated irrigation methods were complementary to each other; while a flooded land in Sarab was recharging the water table of aqueducts, the water current of the same aqueduct irrigated a field in downstream; the drainage water of this aqueduct provided some parts of the discharge of the aqueduct at the downstream (Kowsar, 1993). Although there is not much information on the traditional methods of flood water collection and other irrigation systems, but wise exploitation of soil and water resources by traditional irrigation methods was found in Sistan & Balouchestan, Khorasan, Hormozgan, Boushehr, Fars and Azerbaijan provinces, which is an evidence to the Iranians profound understanding of rules of nature (Farhadi, 2001).

   More than 2500 years ago, the Achaemenian Government created a complex network of irrigation installation to prevent the flooding of rivers and recharge the water resources for the time of drought. According to Herodotus, in that time, the water resources belonged to the Government and by controlling the 20 billion cubic metres of water resources, the Government had succeeded in irrigation of 1.5 million hectares of agricultural lands (Rahmanian, 1999). There is a famous inscription in Persepolis now, on which a sentence from the establisher of Achaemenian dynasty, Cyrus is written as follows: “God protect this country against enemies, drought and mendacities”. This sentence shows how our ancestors were aware of the outcomes of drought and put it at the same level as the unknown enemies; they had experienced its penalties. Even the architecture (overarches and vents, water reservoirs, natural refrigerators, and taking advantage of the heat and light properties of geographic directions) together with the building materials show that our ancestors tried hard to conform with the warm and arid environment of Central and Eastern Iran.

   More than 700 years ago, the people of Tabas, Khorasan province, built a 56 metere high dam in Karit village to control runoff water and floods, and used the reserved water for irrigation of their lands and orchards. This arch dam, uniqe in its kind until 600 years after its construction, still exists 17 kilometeres from Tabas (Fadaiee, 1997). Finally, based on a 600 years old evidence, habitats of Central and Southern Iran, covered the soil with clay, gravel and ceramic mulches to control wind erosion of soil and prevent sand dune movements, and also by building hedges of reed and date palm tree leaves and low earthen walls around the fields, they practically invented and used a kind of vent (Yekom Consulting Engineers Co., 1998).