Abstract
Existing hydrologic landscape classifications, such as Hydrologic Landscape Regions (HLRs) and Hydrologic Response Units (HRUs), group catchments by similarity of climate, geology, and topography, but do not directly link this classification to runoff-generation function, limiting their use for ranking hydrological activity in data-sparse mountain regions. The concept of a landscape–hydrological background, integrating climatic–hydrological, soil–hydrological, and topo–hydrological components, was used as the basis for a classification framework applied to 15 model catchments in the East Kazakhstan Region. The proposed approach provides a functional representation of landscape organization by linking environmental characteristics directly to runoff-generation processes and hydrological activity. The analysis revealed two distinct hydrological domains: a runoff-generating mountain domain (Bukhtarma, Uba, and Ulba), where highly active hydrological landscapes occupy 55.2–63.9% of the catchment area, and a transitional mountain-foothill domain (Narym, Kurchum, and Kalzhyr), where their share decreases to 18.0–25.4%. The highest landscape diversity, with Shannon indices of 1.31–1.53, occurs in the transitional catchments, reflecting the most balanced combination of functional groups. This study demonstrates that hydrological activity is controlled by the combined influences of catchment size, relief differentiation, and the spatial extent of high-mountain environments rather than by elevation alone. The proposed framework has practical applications for watershed management, water resources planning, environmental monitoring, and climate change adaptation, and is particularly valuable for data-sparse mountain regions.