Document Type : Original Article
Authors
1 M.Sc. Student, Department of Water Engineering, University of Birjand, Birjand, Iran.
2 Associate Professor, Department of Water Engineering, University of Birjand, Birjand, Iran.
3 Ph.D. of Hydrogeology, Khorasan Razavi Regional Water Authority, Mashhad, Iran.
Abstract
One of the most unique qanats in the Gonabad plain is the Salaseh Qanat. It is a qanat that has a mother well and one water bearing zone is divided into 3 branches downstream. The aim of this research is to study the structure and determine the qanat catchment boundaries. For this purpose, based on satellite images and field surveys, the path of qanat’s branches in the plain was identified and mapped. Also, using topographic maps of the region, measuring the slope of the qanat tunnel, and water level data from observation wells in the plain, the depth of the mother wells of main and subsidiary branches of the qanat was estimated, and the length of the water-bearing zone of the qanat was determined. Finally, considering the length of the qanat's water bearing zone and the water bearing zone of the surrounding qanats, the hydrogeology and hydrology upstream of the qanat, the boundaries of the qanat's catchment were determined. The qanat has three main branches and one secondary branch with a total length of 36 kilometers and 514 wells. The depth of the mother wells of main and subsidiary branches of the qanat were estimated about 135 and 116 meters, respectively. The depth of the groundwater level at the main branche’s mother well was estimated to be 131 meters and at the subsidiary branch’s mother well at about 119 meters, which indicates that the subsidiary branch has been dry for several years.
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