Analysis of river water yield concentration index (WYCI) and its spatial changes using GIS in Ardabil province

Estimating the natural flow regime of a river is crucial for water resource management. Understanding the temporal and spatial distribution of river flow can greatly assist decision-makers in water resource management. This study aims to analyze changes in the Water Year Classification Index (WYCI) at 31 hydrological stations in Ardabil province (1974 to 2018) at different time scales and its spatial changes using GIS. The WYCI index was calculated at all hydrological stations, and the map of the spatial changes of the index was prepared using the inverse distance weighting method. According to the results, the maximum and minimum median flow values were related to the spring season (3.7) and summer (0.3) cms, respectively. The median flow values in the winter and autumn seasons were 2.5 and 1.3 cms respectively. The results showed that the average values of the WYCI index in autumn, winter, spring, and summer are 11.9, 10.7, 13.8, and 15.2, respectively. The status of the index for dry and wet periods was highly irregular (21.6) and moderately irregular (14.3), respectively. Based on the research findings, the snow-fed rivers located in the southern of Sabalan (Lay, Nir, Atashgah, and Yamchi stations) have a regular regime, while rivers in the eastern part of the province become more irregular towards summer with an increase in WYCI values. Overall, the analysis of spatial changes in WYCI indicates the existence of a unique spatial pattern at different time scales, and it is necessary to consider it in water resource management planning in Ardabil province.