R.V. Borovskaya, S.S. Smirnov
Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”), RF, Kerch, Sverdlov St., 2
This article presents one of the possible methods to solve the problems of water bodies’ detection and estimation of their surface area using data received from the satellites of Sentinel-2 series.
To identify water bodies, the Modified Normalized Difference Water Index (MNDWI), which employs the data of the green range of the visible spectrum and the middle infrared (MIR) range, was applied to multi-spectral satellite images. Using a raster image with MNDWI values as a basis, detection of water bodies was conducted. The described method of water surface area calculation utilized SNAP v 7.0 software package.
The proposed method was tested through estimation of the surface areas of 14 Crimean hypersaline lakes most of which are of fisheries importance signification. As a result, it was found out that the surface areas of Maloye (Small) Yaly-Maynak Lake of Eupatoria group, and Aktash and Kirkoyash Lakes of Kerch group underwent the greatest seasonal changes, while Kirleut and Krugloye (Round) Lakes of Perekop group, Yarylgach Lake of Tarkhankut group, and Oybur Salt and Moynak Lakes of Eupatoria group were shown to undergo the least seasonal changes. Average long-term values of the surface areas of the investigated lakes were lower in comparison with 2004 values, excluding Yarylgach Lake. The largest decrease was recorded for Aktash Lake.
This method along with values of the surface area of Crimean hypersaline lakes obtained by this method are of significant practical significance when applied to assessment and revision of the stocks of the aquatic biological resources inhabiting the water bodies under investigation.
Keywords: method of calculation, remote sensing, detection of water bodies, square of water surface, satellite monitoring, hyperhaline Crimean lakes, lake fisheries importance signification.
LIST OF REFERENCES
- Copernicus Open Access Hub. Complete, free and open access to Sentinel-1, Sentinel-2, Sentinel-3 and Sentinel-5P user products. Available at: https://scihub.copernicus.eu/ (accessed 19.02.2020).
- Step—science toolbox exploitation platform. SNAP: A common architecture for all Sentinel Toolboxes, jointly developed by Brockmann Consult, SkyWatch and C-S. Available at: https://step.esa.int/main/toolboxes/snap / (accessed 19.02.2020).
- Xu H. Modification of normalised difference water index (NDWI) to enhance open water features in remotely sensed imagery. International Journal of Remote Sensing, 2006, vol. 27, issue 14, pp. 3025–3033. doi: 10.1080/01431160600589179.
- Kataev M.Yu., Bekerov A.A. Metodika obnaruzheniya vodnykh ob”ektov po mnogospektral’nym sputnikovym izmereniyam [Methodology of the water objects detection from multi-spectrum satellite measurements]. Doklady TUSUR [Proceedings of TUSUR Journal], 2017, vol. 20, no. 4, pp. 105–108. doi: 10.21293/1818-0442-2017-20-4-105-108. (In Russian).
- Lisovskiy A.A. Poverkhnostnye vodnye ob”ekty Kryma (Spravochnik) [Surface water bodies of Crimea. Guidebook] / A.A. Lisovskiy, V.A. Novik, Z.V. Timchenko [et al.]. Candidate (Geography) Z.V. Timchenko. (Ed.). Simferopol: Reskomvodkhoz ARK [Republican Committee of the Autonomous Republic of Crimea for Water Resources] Publ., 2004, pp. 30–36. (In Russian).