Document Type : Research Article
Authors
Mazandaran Regional Water Company, Water Resources Management Company, Ministry of Energy, Sari, Iran
Abstract
Introduction
Water is a primary and fundamental need for survival, industrial development, and economic prosperity. In other words, the key to development depends on the expansion of water resources and their optimal use. To achieve this, the correct allocation of water resources to different uses based on priorities is of great importance (Loucks and Van Beek, 2017). Any management planning to control water consumption in the agricultural sector requires a correct understanding of the mutual influence of variables controlling water resources and consumption on each other in order to ensure optimal provision of agricultural water needs and also to ensure the improvement of the economic situation of farmers (Veysel, 2024). The purpose of this study is to examine and compare available water resources and uses, including agricultural, drinking, industrial, and environmental needs, for the Tajan River basin, including the two parts of the Tajan Plain and the river basin up to the entrance to the plain during the exploitation season, in order to determine the possible shortage of water supply in different months. It is worth mentioning that the results presented in the report on the study of water resources and needs of the Tajan River Basin (Pandam Company, 1402) were used to prepare this article.
Materials and Methods
The Tajan River is one of the important rivers of Mazandaran Province, which originates from the Hezar Jarib Mountains and flows into the Caspian Sea after passing through the city of Sari in Farahabad. The enJulye catchment area of this river up to the entrance to the plain with an area of about 4050 square kilometers and the Tajan Plain with an area of about 800 square kilometers, has been considered as the study area to investigate water resources and uses. In this study, long-term statistical data from hydrometric stations of the Zaremroud (Garm Rud Station), Lajim (Vastan Station), Chahardangeh (Varand Station), and Tajan (Kordkheil Station) rivers, as well as the inflow and outflow statistics of Shahid Rajaee Dam (during the ten-year operation period of 1390-1400) as the main source of water supply for the Tajan basin, have been used. For groundwater resources (wells), information obtained from the Mazandaran Regional Water Company in 1400 and basic water resource studies have been used. Regarding water ponds, the results of the interpretation of new satellite images in the form of a land use map have been used.
Results
The results of the surveys show that in the entire study area, including the Tajan River basin to the entrance to the plain and the lands of the Tajan Plain, there are about 119,800 hectares of pure agricultural land in the form of irrigated and dry-land cultivation, of which 74,500 hectares are irrigated and the rest are dry-land cultivation. There are fish farming ponds with a total area of 550 hectares in the Tajan Plain, which are generally related to warm-water fish. Also, some of the ponds located in the area are used for aquaculture. The total water requirement of the Tajan Plain area (agriculture and aquaculture) is 492 million cubic meters, and in the upstream lands (the Tajan basin to the entrance to the plain), this requirement is estimated to be 106 million cubic meters. The total drinking, industrial and tourism drinking needs of the region (Sari, Miandoroud and Kiasar counties) are 7.68 million cubic meters per year. The estimated environmental demand of the Tajan River is also equivalent to 100 million cubic meters per year. Available water resources for various uses include the regulated water flow of the Shahid Rajaee Dam, the seasonal flow of the rivers in the middle basin, dam water storage, and groundwater resources. To compare uses with available water resources, three comparison levels including normal, dry, and very dry water years have been used. The volume of water that can be extracted from the Shahid Rajaee Dam in the first six months of the year for normal, dry, and very dry water years is 231, 194, and 122 million cubic meters, respectively. The volume of water that can be extracted from ponds and wells located in the area are estimated to be 12.8 and 176 million cubic meters per year, respectively.
Discussion and Conclusion
A comparison of water needs and available resources indicates that the total water shortage in the Tajan Basin is 166, 231, and 324 million cubic meters in normal, dry, and very dry years, respectively. Similarly, in the Tajan Plain area, the shortages are estimated at 147, 212, and 305 million cubic meters for the same conditions. In other words, in a normal or normal water year, there is a water shortage of about 150 million cubic meters in the irrigation network and the Tajan Plain area. The reduction in available water resources, including decreased outflow from the Shahid Rajaee Dam, leads to resource constraints and consequently causes water shortages in the lands of the Tajan Plain. In the dry water year, the water shortage was mainly due to the decrease in discharge from the Shahid Rajaee reservoir dam and the rivers of the middle basin. Therefore, in addition to the necessity of managing water distribution and scheduling, as well as improving the Tajan irrigation network, which will partially reduce the amount of damage caused by water shortage, the construction of the planned dams on the Zaremroud and Chahardangeh rivers is very important in regulating the monthly discharge.
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