Determining the suitable site for underground dam construction on Qanat A case of study, Dahanchenar Qanat of Kalat watershed in Gonabad

Qanat or Kariz is one of the most surprising collective works of human history that is used for water supply in water shortage regions in order to provide water for drinking, agriculture and livestock in these regions. One of the main problems of Qanat is permanent exit of water. Use of underground dams on Qanat could produce a new method as a solution for this problem. Thus Qanat water is stored in alluvium behind the dam and improve groundwater reservoir of Qanat. But using this technology requires comprehensive studies to determine the suitable site of underground dam construction on Qanat. In this research in order to determine the suitable sites of underground dam construction, a case study on Dahan Chenar Qanat in Kalat watershed of Gonabad is presented. At first the suitable span of Qanat that has initial conditions for underground dams construction is identified and determined. Then in every one of the length span determined suitable sites that have best conditions for construction of underground dams were proposed. At the final stage for all proposed sites the best point for underground dam construction on Qanat via Alluvial Capacity Index was determined. The results of this study showed from total 1000 m length of surveyed Qanat there are only 2 points for construction of underground dams that are the best point determined via Alluvial Capacity Index.