Study region: The Lanzhou-Longmen section of the Yellow River Basin, with particular emphasis on the "Jiziwan" region within the Loess Plateau. Study focus: The study investigates the interannual fluctuations and long-term trends in annual runoff difference (Delta R) between the Lanzhou and Longmen stations from 1960 to 2022. Based on a basin-scale water balance framework, this research utilizes multi-source hydrometeorological observations and hydrological simulation outputs to evaluate the contributions of precipitation, actual evapotranspiration (ETa), consumptive water use (q), and terrestrial water storage changes to the interannual variation and long-term trends of Delta R. New hydrological insights for the region: The interannual variability of Delta R is mainly driven by precipitation variability in the Jiziwan region, accounting for 46.19 % of Delta R fluctuations. ETa also shows a negative correlation with Delta R (34.94 %), but this relationship is largely dependent on precipitation. The long-term increase in Delta R (+1.68 & times;108 m3/yr) is primarily attributed to intensified q, particularly agricultural irrigation and industrial withdrawals in the Hetao region contributing 74.25 % to the trend. A localized "evaporation paradox" is identified, where ETa declined despite rising temperature, owing to the reductions in solar radiation, wind speed, and soil moisture. These findings highlight the dominance of human-induced consumptive water use in altering regional runoff patterns and underscore the need for integrated strategies to manage water scarcity.