Investigating the Relationship between the Spreading of Human Settlements and Instability of Agricultural Water resources in the Zayandeh-Rud Basin

The Zayandeh-Rud Basin, placed in the center of Iran, is one of the areas with water instability problems. In the last decade, the water resources of the basin have decreased. Thus, that part of the length of the river in the middle and downstream of the water flow has dried or temporarily turned off, and the allocation of agricultural water to the agricultural lands of these sectors has decreased significantly. In this study, ground-level land use changes were analyzed through Landsat satellite imagery analysis in 2000, and 2014. These periods coincided with the periods before and after the occurrence of the instability of water resources in the basin. The researchers specified the research area and then divided it into three parts, naming upper, middle, and downstream. At the next step, these parts were compared in the form of 6 categories of use. According to the results, during the period, along with the occurrence of water resource instability, construction and residential land use across the rangelands has increased, and land use of pasture has decreased. Agricultural coverage has increased in the upstream, but it has decreased in the middle and lower parts. Besides, the empty and blank land use on the upstream has decreased, and it has increased in the lower parts. Regarding the results, some of the instability of agricultural water resources in the basin could be attributed to the expansion of settlements, increase in water consumption throughout the area, and increase in agricultural activities in the upstream basin.