عنوان مقاله [English]
Some freshwater resources available in certain watersheds of the world have seasonal limitations and depend on the ability to store water in dry periods. In other areas, restrictions affect the rate at which groundwater aquifers re-feed, the snow melting rate, or the capacity of forest soils to store water. Qarachai watershed is one of these sources in Markazi, Hamedan and Qom provinces, originating from the two main provinces and flowing into Qom Lake. According to the purpose of this project, which is to study the discharge and physicochemical parameters of Qarachai River in order to protect and rehabilitate this source, sampling was performed in four shifts in 68 stations and includes physical, chemical, biological parameters, heavy metals, chlorine toxins, phosphorus, detergents and petroleum hydrocarbons. Results illuminated that the water streams of Tafresh, Bazneh Shazand have an essential role in the flow of Qarachai river during the sampling periods. Mohajeran and Tafresh water treatment plants are of poor quality in terms of biological parameters and also have a high salinity level within Boyaychi bridge stations to the river water station.
“Qarachai River”, “Physicochemical”, “Flow”
Protection and optimal use of water resources is one of the principles of sustainable development of any country. Current surface water or rivers are the most important water resources that play an important role in supplying water required for various activities such as agriculture, industry, drinking and production electricity.
Awareness of water quality is one of the important requirements in planning and development of water resources and their protection and control. It is obvious that in order to be aware of the quality of water resources and produce the required information, the quality of water resources should be monitored. Because having comprehensive, accurate and reliable information with appropriate time periods can be an important factor in decisions and policies (Ministry of Energy, 2009) Monitoring the quality of water resources, various issues such as parameters to be measured, station location. Water shortage in Iran is an inherent issue and to a large extent depends on the climatic and natural features of Iran. But over the past decades, the issue of population growth and consumerism, inefficient agriculture and other factors have increased the severity of water shortages in Iran, and this is also true in Markazi province. Therefore, in addition to the inherent and physical shortage of water resources in Markazi province, the shortage due to some ill-considered measures due to the lack of systemic and forward-looking approach in policy-making and macro-management of water resources in this province have also been involved.
What can be easily deduced from the study of the Qarachai River is that this river has a vital role in the central and western regions of the country, on which the lives of millions of people directly and indirectly depend, and an important role in the ecological balance of this region. Therefore, considering the key role of Qarachai river, especially in Markazi province, where most of its route passes in this province, without having a protection and realistic plan, it will not be able to withstand this amount of pressure in the medium term and without a doubt with many problems. Therefore, the Qarachai River protection program in Markazi province will be an important step in reviving and reducing the pressures on this important river in the country.
Qarachai River watershed is one of the sub-basins of Namak Lake in the central provinces of Hamedan and Qom, and its most important Qarachai River passes through the cities of Astana, Shazand, Arak, Hamedan, Tafresh, Saveh and Qom. In field surveys, it begins with the identification of different uses in the region that can have water abstraction, including rural and urban settlements, agricultural lands, industrial units, aquaculture units, tourist sites and so on. The most important factor in determining the choice of parameters is determining the purpose of the monitoring program. In other words, by determining the objectives of the monitoring program, the parameters to be measured can also be determined.
In general, three environments of water, particles (suspended matter and sediment) and living organisms can be considered to monitor water quality, but monitoring activities are mainly performed on water samples. Water quality and particles (suspended matter and sediment) They are usually determined by physical, chemical, and biological analyzes. Water quality can often be measured by one variable or a set of more than a hundred different variables. The range of chemical, physical, and biological variables is well described.The variables selected in the monitoring programs depend on the objectives of the monitoring program and the existing and projected water uses. Drinks and household uses, agricultural land irrigation, industrial and recreational uses of each Requires a specific water quality The simplest combination of variables to be measured in monitoring discussions can include temperature, electrical conductivity, pH, dissolved oxygen, and total suspended solids.
The best time interval for sampling is monthly, which in the present plan, according to the agreements made, is to be sampled from the river in four (seasonal) seasons.
If possible, the number of samples taken from each sampling station for a period should be between 3 and 5, in the present plan, one sample is taken from each station. But in this sample, all the conditions for that sample to be representative in the desired station, such as the distance from the side and the middle depth of the current will be observed.
In the present study, 65 sampling stations in 7 study areas including Shazand, Astana, Nahrmian, Shara Block, Komijan, Razan-Qahvand, Khanajin, Tafresh and Saveh in Qarachai basin have been selected for sampling.
Among the tributaries of Qarachai River (Azna Astaneh, Toure Nahrmian, Bazneh Shazand, and Abkamard Tafresh (which have a hydrometric station), Toure Nahrmian branch with an average discharge of 2309 liters per second in sample periods Sampling has more discharge than other tributaries. Also the tributaries of Kamard Tafresh, Bazneh Shazand and Azna Astaneh with an average discharge of 1122, 1194 and 1096 liters per second during the sampling periods, respectively, play an important role in the river flow. They have coffee.
Diversion dams along the Qarachai River from Poldoab water station to Joshirvan station, especially in low water seasons, use a large part of the river water for agricultural purposes, so that in agricultural seasons, water flow is usually In the Qarachai River downstream, Joshirvan decreases and causes the river to dry up in the downstream stations.
The important point in the flow of Qarachai river is the decrease or stability of the flow of Qarachai river along the route outside Markazi province. This point is also confirmed by examining the measured flow in Omarabad hydrometric station located on the branch of Hamedan province in recent years. In other words, Hamedan province not only does not have a share in increasing the flow of Qarachai river, but also in some sampling periods such as April 2016, the flow between the outlet of the province was equals 7290 liters per second (47% reduction).