「新たな環境変化に適応するための伝統的技術、カナート」
Semsar Yazdi （カナートと歴史的水利構造物の国際研究センター所長）
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要 旨：
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Global warming could have given rise to climate changes in many parts of the world to a large extent over the past decades. Some regions are struck by destructive floods and unprecedented torrential downpour, whereas some other regions are in the grip of severe droughts. In some areas, the snow coverage is shrinking, resulting in a dramatic decrease in snow melt and the amount of surface streams. Permanent streams are turning into seasonal runoffs, and seasonal runoffs are drying out over time. In such areas the demand for water is still on the rise, though their surface streams are diminishing. Therefore the residents of these areas resort to extracting groundwater which is more reliable to supply water to domestic and agricultural sectors. What may immediately flash trough our mind is that pumped well is the best way to abstract groundwater, though our past experiences in arid and semi arid regions tell that such regions are subject to over-exploitation of groundwater and depletion of aquifer accordingly. In some arid zones, groundwater used to be extracted by the system of qanat over the past centuries without causing any drawdown in water table. Qanat is a horizontal tunnel with a gentle slope that taps groundwater in an area more elevated than cultivated lands. Through this system groundwater is drained out by the force of gravity, fully compatible with nature, without bringing about environmental backlashes.
- This paper is aimed at explaining and recommending the traditional know how of qanat to the regions which turning arid and becoming short of surface streams. In fact if the regions which are affected by climate change use pumped wells in order to supplement the water they need, they would go down the path of the present arid areas where over pumping has done a great damage to groundwater reserves. Qanat never threatens groundwater resources and ensures sustainable utilization of groundwater, so it deserves to be introduced to the areas in need of groundwater.