Remote sensing analysis: A decade of water surface changes in Lake Hamrin, Iraq

Abstract

The study of Lake Hamrin is of enormous importance in understanding changes in water levels and their impact on the local environment. It helps to clarify the role of climatic and human factors in the decline of its water resources from 2013 to 2023 in order to ensure sustainable solutions. Satellite imagery from Landsat 8 is used, and processing is performed using ArcGIS Pro and ENVI. The normalized vegetation index (NDVI) is applied to show the changes in the vegetation cover and reveal the amount of change in the surface water area of the lake. It is noted that the water area changes in one year as it increases in the rainy season and decreases in the summer, and it also varies from one year to another with the difference in the amount of rainfall. In March 2019, the largest area of the water surface of Hemrin Lake appeared, as the water surface area of the lake reached 326.87190 km² due to the increase in rainfall this year. It is noted that the lake's water area decreased during the rainy season due to the lack of rain, as the lake's water area decreased to 121.52340 km² in January 2021, while the smallest area of Hemrin Lake's water surface is reached in October 2021, as the lake's water surface area reached 28.79910 km², and the surface water area became 59.23530 km² in February 2022 due to the lack of rain during this year. In 2023, a relative increase in the lake's water area began to appear due to the return of seasonal rains this year, reaching 80.88570 km² in April, which proves to us that the change in rainfall in the region is one of the main reasons for the change in the area and water level in Hemrin Lake. The values of the earth's surface temperature are also revealed, and these values varied in the study area according to the different elements of the earth's surface and differed from one season to another and from one year to another. It is natural for the surface temperature of Hemrin Lake to rise in the summer and decrease in the winter. As the smallest area of the lake's water surface is 28.79910 km², the value of the lake's water surface temperature reached 24.9°C in October 2021. It is assumed that the area and water level of the lake decrease with the rise in temperature, but in August 2023, when the lake's water surface temperature is 31.9742°C, the lake's water surface area reached 69.75360 km². The main reasons for the decline in the water levels of Hemrin Lake are the lack of rainfall in recent years due to climate change and the lack of water releases from Lake Darbandikhan due to the lack of water coming to it from the Iranian side, as well as the significant decline in the waters of the Alwend River due to its interruption by the Iranian side due to the construction of dams and the change in its course and the cessation of its flow in the summer.