Methodology for evaluation of monitoring river stations homogenity by an optical characteristic of the water surface—the turbidity index

DOI: 10.35595/2414-9179-2023-1-29-330-345

View or download the article (Rus)

About the Authors

Victor Yu. Tretyakov

Saint Petersburg State University, Institute of Earth Sciences,
10th line of Vasilyevsky island, St. Petersburg, 199178, Russia,
E-mail: v_yu_tretyakov@mail.ru

Anna A. Zakolyukina

Saint Petersburg State University, Institute of Earth Sciences,
10th line of Vasilyevsky island, St. Petersburg, 199178, Russia,
E-mail: st110668@student.spbu.ru

Stepan M. Klubov

Russian State Hydrometeorological University, Faculty of Ecology,
11, Rizhsky ave., St. Petersburg, 190103, Russia,

Saint Petersburg State University, Institute of Earth Sciences,
10th line of Vasilyevsky island, St. Petersburg, 199178, Russia,

State budgetary institution of additional education, Palace of Child Youth Art «At the Voznesensky Bridge» of the Admiralteysky district,
26, Grazhdanskaya str., St. Petersburg, 190031, Russia,

E-mail: klubov_stepan@mail.ru

Abstract

Preservation and improvement of aquatic recourses ecological state is an important state goal. The goal demands monitoring of river discharge and hydrochemical parameters of the river. Only the data allow evaluating of ecologically reasonable anthropogenic impact on an aquatic ecosystem. It is evident that homogeneity of river water at a monitoring river station is the requirement of the monitoring data representativity. Of course, regular control of the homogeneity by each of the identifiable hydrochemical parameters is extremely time-consuming task. The paper presents methodology for check of homogeneity of a monitoring river station by means of Earth remote sensing data analysis. The methodology includes calculation of the Normalized Difference Turbidity Index (NDTI) on the base of Sentinel-2 satellite images in geographical information systems ArcGIS and QGIS within buffer zone of a river section, calculation of distances between cell centers of the NDTI matrix and the initial vertex of the river section (the riverside), the results export in Microsoft Excel files, statistical analysis of the NDTI values homogeneity along the river section. The homogeneity analysis is made by means of the Student and Fisher tests when the NDTI distributions belong the normal law of distribution and by the tests of Wilcoxon-Mann-Whitney and Siegel-Tukey otherwise. The data processing is performed by means a number of workflow models and Python-language programs, a Lazarus-language program, and a number of Mathcad-language programs. The tools are elaborated by Victor Tretyakov. An example of the methodology application is provided in the paper. There is considered evaluation of NDTI homogeneity at the Neva River section located downstream from the Slavyanka River outlet into the Neva River. Of course, the NDTI homogeneity cannot ensure homogeneity of the river section for all the hydrochemical parameters. However, absence of the NDTI homogeneity may serve as a mark of the stream flow non-homogeneity at the river section.

Keywords

Earth remote sensing, homogeneity analysis, monitoring river station

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For citation: Tretyakov V.Yu., Zakolyukina A.A., Klubov S.M. Methodology for evaluation of monitoring river stations homogenity by an optical characteristic of the water surface—the turbidity index. InterCarto. InterGIS. GI support of sustainable development of territories: Proceedings of the International conference. Moscow: MSU, Faculty of Geography, 2023. V. 29. Part 1. P. 330–345. DOI: 10.35595/2414-9179-2023-1-29-330-345 (in Russian)