Hidrología: investigaciones actuales

Achieving Ground Water Sustainability in Iran through Qanat Rejuvenation

Abstract

Mehrdad Rahnemaei, Fardin Boustani, and Sayyed Ahang Kowsar

Iran is the land of drought, floods and qanats. The ancient Persians discovered that the best place to store water was under ground, and the most appropriate method for its delivery was qanat. Their groundwater resources were sustainable before the importation of motor pumps and construction of large dams. The pumps enabled them to mine water from aquifers a few hundred meter deep and transporting it to mountain summits. The dam builders were either not aware of our geological and climatological settings, or ignored them. Enormous sedimentation, abundant evaporation, large leakage and astronomical costs make dams the most inappropriate technology for the Land of Iran and other dry lands of the world. Floodwater spreading for spate irrigation and the artificial recharge of groundwater (ARG) provides a low cost technology which is environmentally sound, financially viable and socially acceptable. The ARG on 14.9 million ha of our rain-fed farm fields and rangelands not only saves our groundwater for the future generations, but also rejuvenates about 30,000 desiccated qanats. Maintaining a rather constant flow in qanats is tantamount to groundwater sustainability. Our findings in Iran could be safely copied in other water-short regions of the world were wasted floodwater and suitable potential aquifers are available. We summarize results from a long-term ARG project and contrast them with detailed considerations of problems with the current practice of dams. Our results suggest that the rejuvenation of qanats is the better way to a sustainable water use in Iran.