Temporal changes of streamflow and its causes in the Liao River Basin over the period of 1953–2011, northeastern China

• The annual and seasonal mean streamflows presented significant downward trend.
• The long-term runoff series covered one natural and three human-induced periods divided by turning years.
• The high, low, and median flow in natural period was higher than that in human-induced periods.
• The relative contributions of climatic and anthropogenic impacts on the runoff changes were quantified.
• In the human-induced periods, human activities were the main factor declining the streamflow.

Under the impacts of climate change and human activities, violent fluctuations of streamflow are observed in large river basins in China. Therefore, comparative assessment of the climatic and anthropogenic influence is crucial for better water resources planning and management. This study investigates the streamflow change in the Liao River Basin (LRB), one of the largest basins in northeast China, using long-term hydrological and meteorological data for the period of 1953–2011. The nonparametric Mann–Kendall test, Pettitt test, and cumulative anomaly curve are used to identify trends and change points of the hydro-meteorological variables. In the past 59 years, the annual and seasonal mean streamflow exhibited significant downward trend. The monthly mean streamflow presented upward trends in January, February, and May, while a downward trend was observed in other seasons. Turning points in the streamflow occurred in the years 1964, 1984, and 1998, which divide the long-term runoff series into a natural (baseline) and three human-induced periods. The high (Q5), low (Q95), and median (Q50) flow during the natural period (1953–1964) was higher than that in two human-induced periods (1965–1984 and 1999–2011). The hydrologic sensitivity method was employed to evaluate the effects of climate change and human activities on the annual runoff during the human-induced periods. The results revealed that anthropogenic influence had a far greater contribution (> 56.6%) to the streamflow variability than that by climate change (< 43.4%). Thus, human activities are considered as the most important factor controlling streamflow changes in the LRB.