Title: Hydrogeology and chemo-isotopic characteristics of the deepest qanat in the World, Qasabeh Qanat, East of Iran

Authors: Hojat Mirani Moghadam; Gholam Hossein Karami; Rahim Bagheri

Addresses: Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran ' Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran ' Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran

Abstract: Qasabeh Qanat is the oldest and deepest qanat of the world, has two major branches including Kalat Branch and Kakhk Branch. The water types of Kakhk and Kalat Branches are Mg⁺²-HCO₃^- and Na⁺-Cl^- respectively which after mixing change to Na⁺-Cl^-. Due to the direct cation exchange, the amount of calcium and magnesium deficit in the samples is proportional to their excess sodium. The deuterium (δD) and oxygen (δ¹⁸O) isotopes signatures demonstrate the meteoric origin of the groundwater of this qanat and the flow mechanism is direct infiltration of precipitation through fractures in the limestone and sandstone formations at the south of the catchment and infiltration of surface water in the coarse grain alluvial cones at the south border of the plain. The variation of δ¹⁸O content of precipitation with altitude (-0.3‰/100 m) allows the main recharge areas to be determined above 1,850 m.a.s.l. in Kalat Branch and above 2,050 m.a.s.l. in Kakhk Branch.

Keywords: Qasabeh Qanat; hydrograph; cation exchange; saturation indices; stable isotope; Gonabad; Iran.

DOI: 10.1504/IJHST.2022.120630

International Journal of Hydrology Science and Technology, 2022 Vol.13 No.2, pp.236 - 254

Received: 26 Sep 2019
Accepted: 27 Jul 2020
Published online: 31 Jan 2022 *

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