Determining the effects of large dams and urbanization on soil salinity and surface temperature using satellite images in a Middle Eastern country

Abstract

Land use and land cover (LULC) changes affect natural ecosystems, and surface temperatures have become a major concern for environmentalists and land use planners. Understanding the extent of these changes at the ground level is crucial. Numerous dam constructions in Khuzestan province have significantly influenced LULC, normal difference salinity index (NSDI), and land surface temperature (LST). This study aims to explore these changes and the broader effects of big dam construction on soil salinity and surface temperature. We used satellite images from Landsat 5 and 8 for 1987, 1998, and 2022 to achieve this. The results showed that shrublands, irrigated agriculture, residential areas, and salty and dune lands expanded, with shrublands increasing by 4%. A closer look at the big dams revealed that the Karkheh Dam and its surroundings experienced the most significant temperature change, with a 15 °C difference before and after its construction. Urban areas, however, showed a 6 °C rise in temperature over the past 30 years due to climate change, industrial growth, increased vehicle use, and fossil fuel consumption, contributing to urban heat islands. Also, the NDSI maps indicate increased soil salinity downstream of Gotvand Dam and a significant and increasing trend in EC, indicating a marked rise in soil and water salinity levels. These findings highlight the significant impact of human activities, such as big dam construction and urban expansion, on land cover and surface temperatures. Understanding these changes is essential for developing sustainable land use strategies that mitigate environmental degradation and help manage climate-related challenges.