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Irrigation inIran covers 89,930 km2 making it the fifth ranked country in terms of irrigated area.[1]
TheAbadan Island (Fig. 1) inKhūzestān Province is situated between the Arvand andBahmanshir rivers. TheArvand river (in Arabic:Shatt al-Arab) forms the boundary betweenIran andIraq and collects the waters from theEuphrates andTigris rivers. On the islandorchards ofdate palm are found ontidal irrigation in thedesert climate, although many date palms were destroyed during theIran–Iraq War.
The palm tree belt stretches along the Arvand River from Abadan south-east over a distance of about 40 km and is bounded in the interior by a road.
A sketch of the system of tidal canals[2] is shown in figure 2. They are 2 to 6 km long depending on the topography and spaced at 50 to 60 m.
The tidal canals cut through and serve thelevee soils along the river (Fig. 3) and they stop where thebasin soils of thebackswamps begin.
Field channels originate from the lateral ditches at a spacing of 10 to 12 m and the date palms are planted along these (Fig. 4).
The typical properties of thelevee soils are shown in figure 5.
Thetidal movements are 2 m on average. A simulation of tidal fluctuations in the ditches is shown in figure 6 for an average and a high river discharge at various distances from the sea. The simulations were made with the Duflow[3] model.
Reference:Irrigation, groundwater, drainage and soil salinity control in the alluvial fan of Garmsar[4]
Theirrigation system for thealluvial fan ofGarmsar is quite well developed (Fig. G1, below), to the extent that lined canals have been made and a belt-canal crosses the fan through its middle.
An estimated average annual water balance is shown in Fig. G2 (below). It is seen that the storage of irrigation losses in theaquifer plays an important role. In thedry season thegroundwater is used for irrigation by pumping from deep wells. A cross-section of the groundwater situation is shown in Fig. G3 (below).
Thewater rights are expressed insang, a measure of continuous flow of about 10 L/s, but in practice it varies from 10 to more than 15 L/s. The water is delivered to about 100 tertiary units (often a village), within which the water is distributed by 12-day rotations amongst the farmers who each are entitled to receive the authorizedsangs for a fixed number of hours during each rotation period. The village communities are, at the same time,water-user associations who take care of thewater-distribution within the tertiary unit and they maintain the tertiary canals.
At present, the distribution of surface irrigation water to the villages is determined by the Garmsar Water Authority on the basis of the water rights and verbal agreements and communications with the water users in the absence of a written manual. The fair distribution of the irrigation water is not an easy job as the average annual river discharge is quite variable in the range of 5 to 20 m3/s (see graph at the right).
The deep tube-wells are privately owned. The drilling of wells is subject tolicense. Recently, the licensing has stopped for fear ofover-exploitation of the aquifer. It appears that no operational rules are applied to the wells. In the fringe lands, the water table is shallow.
To stabilize the agriculture in the fringe lands, which are threatened bysoil salinization, a method of strip-cropping (Fig. G4) can be recommended forsoil salinity control.
As of 2021,Pipeline transport lines links (usingdesalination techniques)Persian Gulf toYazd in central Iran. Other similar projects have been launched linking Isfahan, Mashhad or Zahedan to littoral water sources.[6]
According to the plan, water will be transferred fromSari to the city ofSemnan within 24 months (starting April 2012). The plan aims to providecentral provinces with water for industrial and agricultural purposes at a cost of $1.5 billion. Once the plan comes on stream, some 500 million cubic meters of water will be transferred per annum.[7] Afterdesalination at the point of origin in theCaspian Sea, it will be transported through a 500-kilometer-long (300 mi) pipeline to the centralKavir desert, bringing about 200 million cubic meters (7,062 cubic feet) of water per year.[8]
Nearly 14 percent Iran's territory is desert and suffers from prolonged droughts.[8]
The Caspian Sea is shared by Iran, Russia, Kazakhstan, Azerbaijan and Turkmenistan. Its salinity is about a third of that of sea water.[8]