Abstract
The paper presents a spatiotemporal assessment of the ecological state and the level of anthropogenic impact in the Teris River basin (Zhambyl region) based on long-term data from remote sensing for 2015-2025. The information basis of the study was the satellite data of Landsat 8 and 9 (Collection 2 Level 2), processed in the Google Earth Engine environment using atmospheric correction procedures, cloud masking and normalization of spectral indicators. To quantify the key components of geosystems, the NDVI (vegetation), WET (moisture component of the Tasseled Cap transformation), LST (temperature of the Earth's surface) and NDBSI (dryness and degree of anthropogenic transformation) indices were calculated. The integration of standardized indicators was carried out using the principal component method, followed by the formation of an integrated environmental status index (RSEI). The results obtained indicate a pronounced spatial differentiation and high interannual variability of environmental conditions. Throughout the entire study period, the structure of the territory was dominated by the «below average» and «average» classes, the combined share of which exceeded 70 % in most years. The largest share of the «medium» class was recorded in 2016 (56.88%), while in 2025 there was a significant expansion of the «high» class (34.29 %), reflecting a local improvement in the environmental condition. Zones with low RSEI values occupy limited areas (up to 1.34 %), but are spatially confined to areas of intensive land use and degraded lands. The most favorable environmental conditions are typical for mountainous and floodplain landscapes, while central and agriculturally developed areas show reduced integral indicators. The results of the study confirm the methodological viability of RSEI as an integral tool for monitoring the dynamics of the ecological state and assessing anthropogenic load within the basin geosystems of semi-arid regions.