Document Type : Original Article
Authors
1
Ph. D student in Environmental Planning, University of Tehran, Tehran, Iran.
2
Assistant, Professor of environmental faculty university of tehran
3
Department of Geology of Mineral and Water resources, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran
Abstract
Background and purpose: evaporation-transpiration is one of the essential parts of the water cycle balance. Over 0.72% of the country's water resources are unavailable due to evaporation-transpiration. These factors show the importance and necessity of optimal use of water and accurate prediction of actual evaporation and transpiration in various applications such as agriculture and water resource management, including irrigation planning and plant growth modelling. Accurate evapotranspiration estimates are essential in studies such as climate change, sustainable development and water resources control. This research aims to investigate the process of thermal changes and the rate of evaporation-transpiration of the Tabriz metropolis using remote sensing.
Materials and methods: In this research, due to the high accuracy and adaptability of the Sabal algorithm, as well as remote sensing techniques, the Sabal algorithm and Landsat satellite images were used to estimate evaporation and transpiration. For this purpose, Landsat satellite images in sensors ("OLI_TIRS") from 2013-2021 have been prepared from the website of the National Aeronautics and Space Administration (NASA). Also, in this research, the techniques of thermal remote sensing and geographic information system were used, which were combined effectively and efficiently. This study used ARC Gis 8.10 software to prepare the output and Envi 3.5 software to process, analyze and analyze Landsat images.
Results and discussion: This research showed that since 2017, the orange and red parts of LST have increased. Pixels with temperatures of 315 to 320 and 320 degrees and above have prevailed in the studied area. The NDVI index showed that yellow and red pixels (0.2-0.4) and (<0.6) have increased. The index (BT) has increased, and 310-315 pixels have been replaced by 320-315 and 320 and above. The evaporation-transpiration results showed an upward trend in evaporation-transpiration, and it increased from 2017 to 2021 in part outside the city centre.
Conclusion: According to the results of this research, evaporation-transpiration has increased outside the city centre; in the parts where the temperature increase has been recorded, the rate of evaporation-transpiration has also increased, and a significant relationship has been documented. It is also suggested that according to the results of the research in the years 2017, 2019 and 2021, visible changes have been recorded outside the city centre in evaporation-transpiration to use the daily, monthly and annual formula in future research.
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