Tendency of change in water quality of the main Shirvan collector over a long period

The article examines the tendency of changes in the hydrochemical regime of the water of the Main Shirvan collector over a long period of time and the suitability of the collector water for irrigation. Continuous laboratory analyzes performed between 2004 and 2019 were compared to 1986. According to experimental data, it was determined that the hydrochemical regime of the collector water is gradually improving, and the salt content is decreasing. The degree of mineralization of the collector water decreased by 2.3 times, the total hardness by 2.2 times, the number of chloride ions by 10.5 times, the number of calcium ions by 1.3 times, the number of magnesium ions by 2.8 times, the total number of cations sodium and potassium decreased by 3.9 times. For 2004-2019 biochemical oxygen consumption in collector water increased 7.9 times, chemical oxygen demand increased 7.5 times, and the number of suspended particles increased 9 times. The amount of iron ions in water decreased by 2 times, while the amount of aluminum and zinc did not change. The suitability of collector water for irrigation was determined according to 7 internationally accepted assessment criteria. Collector water is considered suitable for irrigation in accordance with 6 assessment criteria - the degree of salinity, irrigation coefficient, sodium sorption coefficient, potential salinity, water alkalinity index and percentage of sodium, as well as 1 criterion not suitable for irrigation - the percentage of magnesium. Collector water can be used to irrigate crops.