Tuesday, November 15, 2011

Ancient irrigation methods an admirable innovation

Water has always played a key role in  the  long history of  IRAN. Iranians are credited for qanats and the invention of  Persian wheel, two ancient irrigation systems which are well known in the world. According to hereto  the Greek  historian, Qanat digging technique  was  documented   and   was   practiced    in   the achaemenids era (550_330 BC) 2500 years ago. Remains of   reservoirs   have  been  discovered   along   with  water intakes, spilwaysand  outlets  and   the   sewage  systems belonging to pre_achamenids and Assyrians (1500-600 BC).
The  archaeological  surveys  suggest  that  Iranians enjoyed advanced  culture  and  civilization  some 7000  years  ago. The civilization of  in  the  western  part of  Iranian plateau flourished 5000  years  ago  and  they  invented   cuneiform writing . Discoveries  prove that Iranian were peaceful and ingenious  people  in  third  millennium  BC  who cultivated cultivated land and raised crops and livestock.
1-Khaju bridge & diversion dam, Isfahan province, Age 354 years
In  general , there   have  been  four  methods  of   in irrigation in Iran .
These four  methods  are  listed as cisterns or  water reservoirs, channels, canals, weirs and dams. Conventional wells were drilled vertically by  means of  manual tools and equipment's and  the water content  of   these wells was discharged  for utilization by  men  or   through the use of  herbivorous animals . Ancient  Iranian  perceived the process by which artesian well originated knew how they could be brought under subjugation. 

However full  utilization of  the aforementioned well was  not accomplished  in  the  past, Furthermore excess precipitation was stored in certain locations known as cistern or water reservoirs, in the form of covered structured ,filled with water ,can be observed in vicinity of salt desert , and hot arid plains in south of Iran which are utilized for provision of water demands of villages and caravans.
Dam construction in Iran dates back to sassanian era, at the time of king shapur I. The dams made at that period are 1300 –1700 years old. A regulating dam and a bridge diversion dam(500 meters long with 4 spans) in shushtar are among these dams.
Amir dam constructed by buyids dynasty 35 km north of shiraz is 1000 years old. this three-purpose dam (irrigation ,bridge and mill) still exist and functions. During the safavids empire (1501-1736) water engineering developed significantly and many storage and diversion dams and bridges were constructed in Esfahan and Mashad of which some still exist.

1- Bahman weir dam, Fars province, Age 2000 years

4- Fariman weir dam, Khorasan province, Age 400 years
General characteristics of old dams in Iran:
As proved by the recent studies , Iranian carefully considered   the three basic  factors i.e. site selection , foundation  condition and  construction materials . In all cases they  fully observed all design and technical  requirements  and circumstances in the dam site and site selection. Topography, river  regime, material  availability and river diversion during construction were also profoundly attended to. Types  of  Ancient  Dams:
All  Iranian   ancient   dams   are   considered  of  following  masonry  types. Gravity  dams:
Studies   indicates   that    all  the   design  criteria considered in the  recent design  of  gravity dams  were taken  into  the consideration  in  the design of   Iranian  ancient  dams. saveh and  sheshtaraz dams  which are over  700 and 900  years   respectively  are  examples of   this  type. Arch dams:
Iranian   perceived   the  high  bearing  of   arches  before Romans . Kebar  and  Kerrit  dams  over 700 and  400 years    old  respectively  are  both   arch  dams. Buttress dams:
Akhlemad  dam  with a crest  length  of  230m , height of 12 m and reservoir capacity of 3 million  cubic meters and Fariman dam, 400 years old , are  both  buttress  dams.  Both  dams  are  still under operation.

3- Golestan weir dam, Khorasan province, Age 300 years

2- Amir dam, Fars province, Age 1000 years
The under ground water channels , the so called "Qanat"  was by the large the most  important method Of  irrigation in many  parts of  Iran.
In view of the scarcity of rivers in  many  regions of  the  country  and  With  consideration  that  the number  of  perpetual rivers was highly scanty the ancient   Iranian   chivied an admirable innovation known as "QANAT" or "CAREEZ"  approximately  3000  years  ago.
This highly  important and  incomparable initiative was transferred  from middle east later transferred  From  middle east to north Africa , Spain and Cecil for further exploitation. The records on the  Iranian's "QANAT" in  the achaemenian period can  be  found  in  the  writings of  Greek  historian . Consequently ,  it  can   be  asserted that   this irrigation technique  dates  back  to the prechaemenian period . There also   exist   historians  records in Qanat   in   the  parthians  and  sassanids.
Qanat (3000 year ancientness)
A symbol of Iranian Identity and National skill in Irrigation
Name : Fahraj Qanat (Subterranean Canal)
Length(km) : 20
Depth(m) : 50
Location: Yazd Province


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