Livestock pressure and ecohydrological stability of the Orkhon river basin, Mongolia

The Orkhon River basin is a major socio-ecological region of Mongolia where rangeland use, climate variability, and watershed processes are tightly coupled. This article investigates how growing livestock pressure reshaped ecohydrological stability in the basin during 1990–2025. The analysis is based on a focused synthesis of the author’s doctoral dataset, including official livestock statistics, landsat-derived land-cover and vegetation information, hydrometeorological observations, GIS-based spatial comparison of pasture use and environmentally sensitive sectors. The evidence indicates that total livestock numbers increased by about 2.2 times after 1990 and that herd composition shifted toward a larger share of goats. Grassland remained the dominant land-cover type, yet it became more variable through time, especially during dry periods and in areas exposed to concentrated grazing. Bare land expanded during major degradation intervals, while wetland and water-related surfaces contracted overall. The middle and southern parts of the basin show the strongest coincidence of intensified grazing, vegetation drought, and reduced ecohydrological buffering capacity. In practical terms, these changes lower infiltration potential, weaken soil-moisture retention, and make runoff generation more seasonally unstable. The article demonstrates that ecohydrological vulnerability in the Orkhon River basin can not be attributed to climate forcing alone; it is reinforced by herd growth, herd-structure change, and uneven spatial concentration of grazing pressure. The results support climate-adaptive pasture management, carrying-capacity regulation, and basin-scale restoration planning.