Possibilities of GIS technologies for predictive detection of areas of solid flow discharge within water protection zones

Abstract

The article considers the modern possibilities of GIS technologies for monitoring the state of the soil cover and water erosion processes. The possibilities of using the Normalized Diference Vegetation Index (NDVI) to assess various types of vegetation cover are shown. The substantiation of the choice of a key site, which includes both water protection zones and landscape positions associated with them in terms of material and energy flows, is presented. A method for obtaining a vector layer of NDVI values calculated from 9 Sentinel-2 satellite images for the period from March to November 2021 is presented. NDVI values are classified and the cells of the vector layer are combined into classes. Methods for obtaining rasters (with formula reduction) of the Topographical Wetness Index (TWI) and the Stream Power Index (SPI) on the territory of a key area are presented. The vector layer of NDVI values was compared with the TWI and SPI rasters, as well as with the average daily air temperature values. The dynamics of NDVI values for March–November 2021 is shown in the key area, a schematic map of the vector layer of NDVI values, ranked by class, is shown. The calculation of the ratio of areas of different classes in the key area was carried out. Topographical Wetness Index (TWI) and Stream Power Index (SPI) rasters are shown. Examples of queries to databases of layers obtained as a result of intersection of vector layers are given: TWI and NDVI, SPI and NDVI. Schematic maps have been obtained based on a combination of NDVI, TWI, SPI values, showing potentially erosion-hazardous areas. When comparing the average daily air temperature values with the average NDVI values, it was found that the correlation between them is 0.89. Possible measures aimed at reducing the environmental load on the water protection zone are proposed.