Qanat system, an ancient water management system in Iran: History, architectural design and fish diversity

Ancient Iran is one of the leading civilizations that actively appear to water resources management, especially by the invention of “Qanat”, an artificial underground system/ subterranean tunnel-wells system where the water flows through gravity on a slight slope in arid and semi-arid regions at least 5000 years ago. Qanats were innovated in ancient Iran, spread throughout much of the Middle East, and extended into North Africa, Spain, Italy, and South Asia. Tools preparation, size selection, digging the first and deepest vertical shaft known as “mother-well”, digging several other vertical shafts along a line between the mother-well and Qanat outlet, and constructing a horizontal connection between vertical shafts (known as the main tunnel), which guides the water out through an outlet, are the main steps in Qanat construction. By this innovation, Iranian solved their water-related problems using the basic concepts of Hydraulics. In the same way, water-related infrastructures were built using locally available materials to make a better life for humans and other wonderful well-designed and well-adapted organisms in dry and semi-dry regions, yielding great civilization with a simple, but a fantastic architecture that provides cold water in hot summer and warm water in cold winter. By means of these ancient underground structures, water was funneled from mountainous areas and aquifers to lower lands and thus alluvial fans could be opened up to settlement, and an agrarian civilization developed and evolved. In addition, Qanat provides a continual flow suitable for many aquatic organisms, including crabs, amphipods (gamarids), freshwater shrimps, and fishes. Qantas are home and refugia to about 42 fish species (36 native and 6 exotic species) belonging to 20 genera, 7 families, and 2 orders. The Qanat ichthyofauna is dominated by Cyprinidae with 19 species (45.2 %) followed by Leuciscidae and Nemacheilidae (6 species, 14.28% each), Poeciliidae and Aphaniidae (4 species, 9.52%), and Cobitidae (1 species 2.38%). It is about 14% of the total ichthyofauna of Iran. The Qanat ichthyofauna comprises 36 natives (including 20 endemics) and 6 exotic species. Qanat fauna dominates by species that are generally of small size, are broadcast spawners, nonmigratory, and have a wide tolerance of environmental conditions.