Subsurface dams and aqueducts have been used for many years as important sources of water in different parts of the world. Nowadays, little attention is paid to aqueducts. On the other hand, there is a great tendency for constructing and using subsurface dams in many arid and semiarid parts of the world such as Iran. A combination of these two structures was established in ancient Iran including Qanat Vazvan in Isfahan. Nowadays, new methods and techniques such as the Geographic Information System and Remote Sensing have been developed to process site selection of subsurface dams with high accuracy and in a short time. Study and research of the Qanat Vazvan structure emphasizes the idea that these two structures have been combined in a new way. Considering some main criteria and sub-criteria for subsurface dam site selection, with the existence of aqueduct, some suitable locations with a combination of aqueduct and subsurface dam in Pishkoh basin, Taft, Yazd province have been delineated. Some of the advantages of underground dams are their local use, being close to the demand sites and their capacity for gathering water in each season. These positive points when combined with reclamation of aqueducts (qanats) cause a renewable situation for qanats and their efficiency as a water resource management process. Underground dams can be built in a qanat's shaft by constructing some hatches inside the dam's wall. Hence, water can be stored during cold rainy seasons. The main and basic weaknesses of qanats can be covered through this combination. Hence, it causes a strong and optimum usage of qanat water.
Comparative study on dam site selection in the pre-feasibility stage of Shitouzhai Hydropower Station