Spectral Indicators for Detecting Hydrological Changes of Southern Iraq Using RS-GIS

Abstract

Water resources are the lifeblood of arid and semi-arid environments. They are of great interest to researchers, particularly in areas whose economies are based on agricultural activity. This contributes to optimal and effective investment of water resources, as water is a strategic resource that defines economic development. The research aims to study the hydrological changes in southern Iraq and its causes for the study area located between -29.5° 32.45°N latitude and -45.66°-48.40°E longitude, which occupies an area of (47764,63 km) and constitutes (11%) of the area of Iraq, located in the southern and southeastern part of Iraq and overlooks the head of the Arabian Gulf in its southeastern part, and is bordered to the north by Wasit Governorate, to the south by Kuwait and the Arabian Gulf, to the east by Iran and to the west by Al Qadisiyah and Muthanna governorates. In this study, multispectral bands of MSS, ETM, TM, and TIRS-OLI were downloaded to estimate the normalized water variation index from the USGU website in the United States of America, and then multispectral packages were prepared for subsequent calculations by analyzing the data. By analyzing the satellite visualization of the surface areas of the waters of southern Iraq during the period (1975 - 2024) 2024), it was found that there is a spatial change represented by a large variation at the annual level for the selected years, as the largest hydrological change was observed in southern Iraq in 2000, as the areas of the marshes shrank significantly, including Haw al-Hawiza (the marsh), and some marshes dried up completely, including Hawr al-Hammar, as only a part of Hawr al-Sanaf remained, as well as the central marshes and the marshes southeast of Gharaf. Only part of Hoor Al-Sanaf remains, as well as the central marshes and the marshes southeast of Al-Gharaf dried up, as the area amounted to (662,75 km2), after the water area occupied large areas in 1975 (6596 km2), as shown by the NDWI index maps installed in the body of the research, then the water areas returned to occupy large areas in 2005, as it reached (6596 km2). Large areas in 2005, reaching (2085 km2) as a result of the revitalization of the marshes that occurred after 2003, but soon the water areas began to decline in 2010, reaching (1029 km2) as a result of the drought that occurred in this year and the lack of water income and the cutting of some tributaries feeding the rivers, then the water areas returned to occupy large areas in 2020 as a result of the increase in water income reaching the study area, and the year 2024 witnessed a decline in water areas due to the drought that occurred, thus the hydrological situation in southern Iraq has seen a stark contrast between water abundance and scarcity Therefore, hydrological changes are among the most dangerous and complex problems facing the study area due to the multiple causative factors, including drought resulting from high temperatures and consequently a decrease in total rainfall and its fluctuations, and a decrease in the water supply of the study area, which led to a decrease in water areas, in addition to poor planning and management represented by weak management of water supply (dams and reservoirs) and water demand (water consumption for various types of use).