Assessment of land use/land cover changes induced by Jizan Dam, Saudi Arabia, and their effect on soil organic carbon

Abstract

Land use change has been influenced by human activity and has altered an enormous part of the natural landscapes of developing countries. Meanwhile, as the largest pool of terrestrial organic carbon, soils interact strongly with atmospheric composition, climate, and land cover change. The objectives of this study were to assess the land cover and existing land use changes in Jizan Basin, Jizan Province, Saudi Arabia, as an aftermath when Jizan Dam started working, and, subsequently, to assess soil organic carbon distribution in different land uses in the study area. Three cloud-free Landsat MSS, ETM+, and OLI images covering the study area were employed for analysis. Images were acquired in years 1972, 2000, and 2017, respectively. All images were manipulated using ERDAS Imagine 10 software to achieve the aims of this study. The final output maps have been produced using Arc GIS 10.1. Different methods of data transformation and analysis were applied including normalized difference vegetation index (NDVI). A supervised classification approach was applied to categorize the images in different land cover classes. Five land use/land cover classes were identified: vegetation, bare soil (sand), bare soil (rocks), urban area, and water bodies. The results show that the vegetation of Jizan Basin increased between 1972 and 2017. The area increased 4% of its total area between 1972 and 2000 with an average annual increment of 0.45%. This annual rate increased to 1.05% during the period of 2000–2017. The major change has been found in the bare area (sand) cover which decreased during the period of 2000–2017 to about 42 km2 (9%). The results prevail that there is a significant increase in vegetated land in Jizan Basin which could be connected to Jizan Dam construction. It is important to mention that in conducting the present study, actual clear land cover changes took place as the result of agricultural land development. These changes in land cover influenced soil organic carbon sequestration.