Identifying land use/land cover changes using remote sensing and gis techniques in upper, middle and lower reaches of zayandeh-rud basin in central Iran

The Zayandeh-Rud River basin, located in central Iran, has been one of the areas suffering from water instability problems. The water resource of the basin has diminished in the last decade, and consequently, the middle and downstream reaches of the river have temporarily dried or stopped flowing. Furthermore, there has been a serious decrease in water allocation to agricultural sector in these areas. In this study, ground-level land use changes were analyzed through Landsat satellite imagery analysis at two time periods, i.e., 2000 and 2014, which coincided with a period of instability in water resources of the Zayandeh-Rud River basin. The study area was divided into the upper, middle, and downstream reaches, and the results depicting areas under six land uses during 2000 and 2014 were compared to find changes in the land use. The results indicated that during these two periods of water resource instability, built-up and residential land uses all along the basin increased by 66.00 km²; therefore, the pasture land area decreased by 80.0 km²;. Agricultural coverage in the upper reach increased by 108.85 km²; however, it decreased by 328.00 km²; in the middle reach and by 147.00 km²; in the lower reach. Conversely, barren land without cover decreased by 86 km²; in the upper reach, by 320.00 km²; in the middle reach, and by 183.00 km²; in the lower reach. According to the results of this study, some of the instability of agricultural water resources in the basin may have been intensified by the expansion of residential settlements, increase in agricultural land in the upper reach of the basin and generally mismanagement of land and water resources in the basin.