Zayanderud

The Zayanderud or Zayandehrud (Zāyanderūd ,زاینده‌رود; from زاینده "fertile" or "life giver", and رود "river"), also spelled as Zayanderud or Zayanderood, , is the largest river of the Iranian Plateau in central Iran.

The Zayandeh starts in the Zard Kuh subrange of the Zagros Mountains in Chaharmahal and Bakhtiari Province. It flows eastward before ending in the Gavkhouni swamp, a seasonal salt lake, southeast of Isfahan (Esfahan) city. The Zayandeh used to have significant flow all year long, unlike many of Iran's rivers which are seasonal, but today it runs dry due to water extraction before reaching the city of Esfahan. In the early 2010s, the lower reaches of the river dried out completely after several years of seasonal dry outs. The Zayandeh River basin has an area of , an altitude from to , an average rain fall of and a monthly average temperature of 3 °C (37 °F) to 29 °C (84 °F). There are of irrigated land in the Zayandeh River basin, with water derived from the nine main hydraulic units of the Zayandeh River, wells, qanat and springs in lateral valleys. Zayandeh River water gave life to the people of central Iran mainly in Isfahan and Yazd provinces. Before the drying out, water diverted per person was 240 litres (63 US gallons/53 imp gallons) per day in urban areas and 150 litres (40 US gallons/33 imp gallons) per day in villages. In the 1970s, the flow of the river was estimated at per annum, or per second.

People have lived on the banks of the Zayandeh for thousands of years. An ancient prehistoric culture, the Zayandeh River Civilization, flourished along the banks of the Zayandeh in the 6th Millennium BC. The Zayandeh crosses the city of Isfahan, Iran. In the 17th century, Shaikh Bahai (a scholar and adviser to the Safavid dynasty), designed and built a system of canals (maadi), to distribute Zayandeh water to Isfahan's suburbs. The Zayandeh riverbed is spanned by Safavid era bridges, and the river used to flow through parks. American archaeologists and historians of Persian art, Arthur Upham Pope and his wife Phyllis Ackerman are buried in a small mausoleum on the river bank. Richard N. Frye (an American scholar of Iranian and Central Asian Studies) has also requested to be buried there.

Until the 1960s in Isfahan Province the distribution of water followed the Tomar, a document claimed to date from the 16th Century. The Tomar divided the flow of the Zayandeh River into 33 parts which were then specifically allotted to the eight major districts within the region. At the district level the water flow was divided either on a time basis, or by the use of variable weirs, so that the proportion could be maintained regardless of the height of the flow. While the drying out of the lower reaches of the Zayandeh River has been attributed to drought, the main reasons are man made. Poor planning and populist politics have led to years of mismanagement and overuse which resulted in seasonal dry outs and ultimately caused the river to dry out completely before reaching Isfahan.

Zayandehroud River lost its permanent flow since 2006 and the people and farmers of this city faced a water shortage crisis. In addition to the lack of water due to the lack of snow and rain, the main reasons for the drying up of Zayandehroud are related to human errors, which can be summarized in the following cases:

Converting 180,000 hectares of natural resource pastures into gardens upstream of the Zayandehroud River in Chaharmahal and Bakhtiari province and Faridan region. Creating structural dams and reservoirs for the development of agriculture in the mirage of the watershed. Establishment of large industries such as Isfahan Iron Smelter, Isfahan Oil Refinery, Isfahan Petrochemical, Chemical Industries, Mobarakeh Steel Company, Sepahan Oil Company and many industries that use a lot of water, such as power plants, etc., on the banks of Zayandeh River. The dryness of the river has caused hundreds of thousands of residents down the river to become unemployed and has led to their seasonal or complete migration to other provinces or the city of Isfahan. This has caused a lot of damage to the farmers, so that during these years the farmers of Isfahan have rioted and protested at different times.

As of November 2023 a water supply tunnel Kohrang has been under development by Iranian government for more than 20 years. The government Minister of Energy said the river would be opened five years from 2024. In 2015 the government promised to fully open the river in 2018 then in 2021 promised to do it in 2023. The government had reallocated the water from the river to other provinces cities and industries from 1980s. A database for water share allocating had been proposed.

In the section of the Zayandeh River crossing Esfahan, bridges, parks, paddle boats and traditional cafes and restaurants amongst the rest of Esfahan rich cultural heritage, are major tourist attractions for Iranian as well as international visitors.