WATER REGIME CHARACTERISTICS OF FLOODPLAIN LANDSCAPES IN THE GNYLOPYAT RIVER BASIN BASED ON MULTISPECTRAL DATA OF THE NORMALIZED MNDWI INDEX

Abstract

The article is devoted to studying the water regime characteristics of floodplain landscapes in the Gnylopyat River basin using the MNDWI multispectral index and modern remote sensing methods. The research objective is to establish patterns of seasonal dynamics and spatial differentiation of floodplain wateriness to substantiate scientific-practical approaches for monitoring and managing water resources of small rivers in the Polissya region. The study is based on comprehensive analysis of Landsat satellite data for 2022–2024 using the Modified Normalized Difference Water Index, which demonstrates high efficiency in detecting water surfaces while minimizing the influence of built-up areas and vegetation. Hydrological features of the 2150 km² basin were analyzed, including long-term runoff dynamics for 1991–2020 and water balance structure considering the role of infiltration-influent processes. MNDWI values show pronounced seasonal variability with maximum indicators during spring period due to snowmelt and floods, and minimum values during summer-autumn season. Progressive increase in floodplain landscape wateriness was revealed throughout the study period, especially in central and southern parts of the basin, where maximum MNDWI values exceeded 0.4000, indicating formation of new water surfaces or groundwater level rise. Spatial differentiation of water content closely correlates with geomorphological features of the floodplain: highest index values are characteristic of central lowered parts with prolonged water retention, while peripheral areas demonstrate better drainage. Research results reveal ecological significance of regime characteristics for floodplain biocenosis functioning and have important practical value for optimizing hydroecological monitoring, developing river basin management plans, and integration into early warning systems for extreme hydrological events.