Increased discharge across the Yellow River Basin in the 21st century was dominated by precipitation in the headwater region

Abstract

Study regionThe Yellow River Basin in China. Study focusThe discharge in the lowlands of a watershed is susceptible to the variations in its high-altitude headwaters in terms of climate, land cover/use and anthropogenic interference. This study not only focuses on the key role of the high-altitude headwaters of the Yellow River Basin (YRB) on the water supply in its droughty downstream lowlands, but also analyzes the contributions of the headwaters’ changes to affect the variations of discharge in the entire basin especially in the early 21st century compared to the last half of the 20th century. New hydrological insights for the regionThe results indicated that more than 1/3 of the actual flow out of the headwaters of the YRB supported the excessive water demand (mainly for irrigation) downstream. The observed discharge (QObs) increased by 44.07% in the YRB as a whole before and after the mutation year 2002 during 1986–2019, and 76.45% of the discharge increment derived from the headwaters. The increasing precipitation in the headwaters dominated the discharge recovery of the YRB, and resulted in a relative increase of 36.28% in the QObs of the entire YRB; whereas the variations of the headwaters in terms of potential evapotranspiration, land cover and water use for human activities have decreased the QObs of the entire YRB by 4.68%, 2.07% and 5.10%, respectively.