Investigation of water balance in Iran; Status and challenges

The latest balance of water resources and consumption in the country is related to the water year 2018-2019, during which the balance of water resources leading to the water year 2019-2020 (average period of 45 years) was prepared by the water department of the Ministry of Energy in the form of 609 study areas of the country. The balance prepared for the spatial scales of 30 second-class watersheds, 6 first-class watersheds and finally the entire country is presented. According to this balance sheet, the three catchments of the second degree with the highest water input are: Karun Bozor, Central Desert and Salt Lake, with absolute values ​​of 41,553, 30,243 and 24,985 million cubic meters, respectively. Also, the largest deficit in the reserve has occurred in the secondary catchments of Salt Lake, Central Desert and Urmia Lake with values ​​of -1039, 1006 and -594 million cubic meters. On the scale of the Persian Gulf and the Oman Sea, the Caspian Sea, the Central Plateau, Lake Urmia, Qara Qom and Marzi Sharq, renewable water is obtained with the values ​​of 56929, 22465, 22290, 5071, 1675 and 1447 million cubic meters, respectively, which in the end total Renewable water defines the country. Also, in this scale, all the watersheds have negative changes in reserves. The most important pathological cases of the country's water balance can be listed as the lack of a specific custodian of the unit, lack of updating and long intervals of updating, inappropriate tenure structure in the executive body, and also the lack of clarity of the boundary between measurement and estimation. The aforementioned damages ultimately lead to the ineffectiveness of the balance of water resources and consumption in formulating the policies of the country. In this regard, completing and equipping the country's monitoring network and using modern monitoring and measurement technologies, standardizing the method of preparing the balance and changing to the water accounting approach are presented as some suggestions to improve the country's water balance category.