The response of runoff from inland river basins is becoming increasingly complex due to climate change and intensifying human activities, as well as underlying surface impacts. The annual distribution patter of runoff shows spatiotemporal heterogeneity, which affects hydropower generation, irrigation, ecological-cultural value of river runoff, and put pressure on water resources management projects. 

A research team from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) conducted a research on the outflow of 13 rivers in the Hexi Corridor, including the Shiyang River, Heihe River, and Shule River, to gain a deeper understanding of the runoff change of mountain inland rivers. 

The study was published in Research in Cold and Arid Regionson Apri. 8.  

Researchers used various indexes to analyze the annual runoff changes in the Shiyang River, Heihe River and Shule River Basin. They compared spatial and temporal differences, explored sub-regional boundaries and runoff models in the inland river basin of Hexi Corridor, and identified key time points of change.   

The results indicate that the annual runoff distribution of runoff in different river basins exhibits different trends of change. 

The annual runoff from the Taolai River and its western tributaries, excluding the Shiyou River, has been increasing, while that of the eastern river has been decreasing. Despite these opposite trends, both the coefficient of variation (Cv) and the complete regulation coeeficient (Cr) values (important indicators of runoff variability) for each river remain high. 

The annual distribution of concentration periods in the Shiyang River Basin is widely scattered, with a range exceeding 40°. Some rivers, such as the Huangyang River, have an even wider range of up to 93°, indicating a time difference of about three months for the occurrence of concentration periods.  

In contrast, the Heihe River Basin has a narrower range for concentration periods, showing a more concentrated distribution of runoff. 

The concentration and timing of runoff in the Shule River Basin show significant variations, with distinct concentration periods observed at different times for the Shiyou River, Changma River, and Danghe River.  

It is worth noting that since the beginning of the 21st century, these three basins have undergone a shift towards later concentration periods which indicates climate change has influenced runoff distribution. 

Additionally, the researchers found that the kurtosis coefficient of the flow distribution curve is negative in Liyuan River and eastward rivers, indicating a gentler peak surface and a lower probability of extreme runoff events throughout the year.  

Conversely, except for Dang River, western rivers have a positive kurtosis coefficient, suggesting a steeper peak surface and more concentrated runoff, thereby increasing the risk of extreme runoff events. 

The study provides a crucial foundation for water resource planning and management in the Hexi Corridor, as well as serving as a scientific reference for predicting future changes in regional water resources. 

Contact: 

LU Zhixiang 

E-mail: lzhxiang@lzb.ac.cn