Investigation of Surface Water Dynamics Using the NDCI and NDTI Remote Sensing Indices

This study investigated surface water dynamics using the NDCI and NDTI remote sensing indices, enabling the tracking of the spatiotemporal dynamics of pollution in the Desna and Seim rivers within Chernihiv Oblast, caused by the influx of suspended matter from the Seim River in Sumy Oblast. The application of remote sensing indices is one of the most effective approaches for detecting, monitoring, and analyzing environmental changes. These indices enable the operational observation of anthropogenic impacts, ecological assessment of territories, and tracking of the spatial distribution of environmental pollution. Furthermore, the use of remote sensing indices complements traditional methods for monitoring surface water conditions. In 2024, it was found that the spectral characteristics of surface waters – specifically in the Seim River and the Desna River within Chernihiv Oblast – significantly deteriorated, indicating increased turbidity and suspended matter concentration. The results of the study showed that as of September 3, 2024, NDTI values fluctuated between 0 and 1. This indicated the presence of suspended matter over significant areas of the Desna River after its confluence with the Seim River. The affected zone extended from the “Lavryk” Zoological Nature Monument to the village of Makoshyno in Chernihiv Oblast, where river biota mortality was recorded. At the same time, the analysis of satellite imagery subsets using the NDTI as of September 5, 2024, demonstrated a significant decrease in NDTI values to a range between -0.6 and 0.2. This indicated a reduction in suspended matter concentrations and a gradual improvement of the aquatic environment of the Desna and Seim rivers within Chernihiv Oblast. The obtained results demonstrate the feasibility of using remote sensing data for early pollution detection, assessment of its scale, and monitoring of recovery processes in aquatic ecosystems.