ASSESSMENT OF THE DYNAMICS OF CHANGES IN THE COASTLINE OF THE AZERBAIJAN SECTOR OF THE CASPIAN SEA BASED ON SATELLITE IMAGES

ABSTRACT

The coastline is the most dynamic part of the earth's surface, constantly adapting to the effects of weather, tides , seasons and climate change. Coastal zones cannot withstand overuse; they are inherently unstable and subject to change by (coastal waves and currents, wind). The speed and intensity of erosion processes depend on the morphological, geographical and hydrodynamic characteristics of the coastal zone. Change detection helps analyze shoreline trends and predict their future. The main goal of this study is to assess the dynamics of changes in the coastline on the southeastern coast of the Caspian Sea of the Absheron Peninsula  object methods based on satellite images during 2019-2024.

АННОТАЦИЯ

Береговая линия является самая динамичная часть земной поверхности, постоянно адаптирующаяся к воздействию погоды, приливов, сезонов и изменения климата. Прибрежные зоны также не могут выдержать чрезмерного использования, и поэтому они своей природе не стабильны и подвержены изменениям (прибрежные волны и течения, ветер). Скорость и интенсивность эрозионных процессов зависят от морфологических, географических и гидродинамических характеристик прибрежной зоны. Обнаружение изменений помогает провести анализ тенденций береговой линии и прогнозировать их будущее. Основной целью данного исследования является оценка динамики изменения береговой линии на юго-восточном побережье Каспийского моря Апшеронского полуострова   объектными методами на основе космических снимков в течение 2019-2024 годов.

Keywords: Caspian Sea, hydrological regime, coastline, climate change, remote sensing, object-based methods.

Ключевые слова: Каспийское море, гидрологический режим, береговая линия, изменение климата, дистанционное зондирование, объектными методами.

The most important features of the Caspian Sea include the variability of its level, which experiences long-term seasonal fluctuations, which often become the cause of natural disasters and catastrophes in the Caspian region. The sea level is constantly changing, which significantly complicates the activities of a number of sectors of the region’s economy: fishing and agriculture, the oil industry, sea and river transport, the construction of hydraulic structures, etc. [1-3].

The main factor influencing the level regime of the Caspian Sea in historical times and in recent centuries is the change in climatic factors in the sea's drainage basin. It has been proven that (Fig. 1) both the high sea level in 1900–1929 and the decrease in its level in 1930–1977 , the increase in 1978–1995, and also its recent decrease in 2005–2021. , are caused by changes in hydrometeorological factors [4].

 Instrumental observation curve;  ........ Level trend

 Figure 1. Fluctuations in the level of the Caspian Sea over the past 100 years (the graph is based on data from the Baku Futushtok, based on long-term average sea level values)

Advances in the digital processing of satellite images in recent decades, especially improvements in sensor performance, have created the possibility of more accurately detecting changes in land cover in territories [6]. Because remote sensing data has high temporal resolution, digital computation, and spectral resolution, it serves as a primary source of information in space exploration. Use of this data includes compiling a geographic report of changes that have occurred, determining the type and quantity, and assessing the accuracy of the results.

Peninsula of the Azerbaijan sector on the western coast of the Caspian Sea was taken as the object of study . Satellite images of Landsat-8 OLI and Landsat-9 were compared OLI made on 11/06/2019 and 04/21/2024 .

The Normalized Difference Vegetation Index (NDVI) takes negative values for hydrographic features. NDVI indices are used to assess the vegetation of the coastal zone of the Azerbaijani sector of the Caspian Sea, the dynamics of vegetation and the coastline in connection with sea level changes. Band 5, Band 4 are taken for NDVI.

Using Landsat-8 and Landsat-9 satellite images taken in different years (2019 and 2024), changes in the level of the Caspian Sea were determined and mapped. The images are presented in GeoTiff format and have 16-bit radiometric resolution. The resolution of the infrared sensor of the Landsat-8 satellite is 30 meters, and the resolution (panchromometric) in the 8th band is 15 meters. In addition, it has two thermal ranges separated by a distance of 100 meters. During the research, the coastline of the Caspian Sea for part of the Absheron Peninsula for 2019 and 2024 was deciphered and mapped. Vegetation indices were calculated based on the satellite images we used. Coastline The Caspian Sea was studied and mapped for each year of research. Then, based on satellite images, dynamic changes over different years were identified and mapped. It is known that through vegetation indices, in addition to vegetation, clouds, water or snow cover reflect light better in the visible range than in the near-infrared range. High positive NDVI values indicate that the plants are healthy and well developed. For sushi, the index value approaches zero. The NDVI index values fluctuate in the range [-1.1].

The coastline of the Absheron Peninsula was vectorized for 2 years and changes were detected. Satellite images of bands 2,3,4 were combined to obtain multispectral images. Since georeferencing is not required, Landsat satellite images are available on the website usgsearthexplorer.com ( Fig. 2) with coordinates as source material [6-8 ]. Thus, all the work done was transferred to the map using ArcGIS 10.6. (Fig. 3,4).

Figure 2. Earthexplorer.usgs.gov website window 2019

Figure 3. Map of changes in the coastline of the Caspian Sea of the Absheron Peninsula for 2019

Figure 4. Map of changes in the Caspian Sea coastline of the Absheron Peninsula for 2024

Thus, in this work, a study was conducted to assess changes in the coastline on the southeastern coast of the Caspian Sea of the Absheron Peninsula during 2019-2024. Using Earth remote sensing data based on the object-based method, it has been studied in Geographic Information System ( GIS ) dynamics of changes in the state of the coastline of the Absheron Peninsula of the Azerbaijan sector of the Caspian Sea and the areas of the coastal zones of the sea. These changes were detected based on an object-oriented method. By comparing the results obtained using the pixel method, the coastline of the area where the change occurred was determined. As a result of the research, it became possible to assess the trend of changes in objects and processes that shape the dynamics of the coastline in the future, and to make predictive proposals.

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