عنوان مقاله [English]
The rivers are the most important supplies of fresh and agricultural water in the cities and villages. The importance of chemical quality of waters is becoming increasingly important due to the increase and diversity of Anthropogenic activities in the urban and rural environments. Therefore, the current study aimed to investigate the trend of land use changes and the chemical quality of surface water in a period of twenty years in the Qaranquchai River in Hashtrud Ccounty. The Qaranquchai is one of the sub-basins of Qezel Ozen River in the northwest of the country. In this research, Land use maps for the years 2021 and 2001 were prepared and drawn using Sentinel 2 and Landsat 7 satellite images, and were examined their changes. The chemical quality data of surface water in the hydrometric stations of the Qaranquchai basin, including Mg, Ca, EC, TDS, Cl, HCO, SO4, K and Na were obtained from the Regional Water Organization of East Azarbaijan province from 2000 to 2020. Then, their changes over 20 years were analyzed using the Mann-Kendall test. The results of the analysis of land use changes showed that in 2001, the largest area of land use was pasture, while in 2021, rainfed land had the largest area in the Qaranquchai basin. In fact, during the studied years, with the increase of rainfed agricultural land from 38% to 53.1%, pasture land decreased from 60.17% to 42.3%. The results of the investigation of the changes of the chemical quality indicators of the water in the hydrometric stations in the Qarangochai river in the studied time period, showed that the trend of changes was increasing. The result of the increasing process of each of the anions and cations in the river water has caused its quality to decrease.