Abstract
This study examines the spatial patterns of river runoff distribution in the Northern Kazakhstan, focusing on the Tobyl and Yesil river basins. Hydrological investigations in this region are constrained by the predominance of small rivers and temporary watercourses, which have short observation periods insufficient for robust hydrological calculations. However, small rivers are the most sensitive and vulnerable to contemporary climate change and increasing anthropogenic pressure; therefore, determining their mean annual runoff and other hydrological characteristics is both important and challenging. To estimate runoff for poorly studied and unstudied rivers in the region, graphs of regional relationships between the mean annual runoff modulus and catchment area (M₀ = f(F)) were derived for six hydrologically homogeneous zones. These relationships demonstrated acceptable correlation coefficients ranging from 0.60 to 0.94, enabling their use for estimating mean annual runoff of poorly studied and unstudied rivers in the Northern Kazakhstan, as well as for constructing isoline maps of runoff.