Runoff is affected by both diverse natural factors and anthropogenic activities, which have further altered the hydrology and water quality of rivers.  

To manage water resources efficiently, it is of great importance to distinguish the impacts of climate change and human activities on runoff change in the evolution of the hydrological time series. 

Recently, a research group from Northwest Institute of Eco-Environment and Resources (NIEER) of the Chinese Academy of Sciences analyzed the runoff periodicity and relationship with climate indices of Heihe River Basin using continuous wavelet transform and wavelet coherence. 

Scientists separated the impacts of climate changes and anthropogenic activities on runoff variations using the double mass curve, the slope changing ratio of cumulative quantity and the Choudhury-Yang equation  methods for different potential evapotranspiration data. 

This study is conducted to quantitatively identify the separate impacts of climate change and human activities on changes in runoff for three separate and potential evapotranspiration methods. 

The results demonstrate that the flow regimes in high and low flow seasons were not obvious shifts, and that after implementation of the Ecological Water Diversion Project, ecosystems were gradually restored in the downstream portion of the Heihe River Basin. 

The study also indicates the different potential evapotranspirations have different effects on the separation of climate change and human activities on runoff changes for different methods for annual, high- and low-flow data. 

Additionally, exploring more effective management measures to coordinate ecological and economic water use in the different basins of Heihe river is essential to the sustainable development of the whole basin. 

The study entitled "Runoff variation characteristics, association with large-scale circulation and dominant causes in the Heihe River Basin, Northwest China" has been published in Science of the Total Environment. 

 Meteorological hydrological station, reservoir and digital elevation map (a), LUCC in 2015 (b), vegetation types (c) in HRB. (Image by ZUO Xiaoan)