Attribution of runoff variation to climate and human-driven changes in the transition zone between the Qinling Mountains and the Loess Plateau under vegetation greening

The need for water safety management has increased in the transition zone between the Qinling Mountains and the Loess Plateau, China due to streamflow decline over the past 30 years. Vegetation greening, largely due to the result of the 'Grain for Green' program implemented in the Loess Plateau, is affecting regional streamflow together with climate change and direct human impacts. There is thus an urgent need to evaluate the relative importance of causes of streamflow variation in this region. A Hydrological Model of L ' ecole de Technologie Superieure (HMETS)-based segment identification analysis framework was presented to quantify the impacts of climate and human-driven changes on runoff under regional vegetation greening. Results showed that climate change and human interference were alternately dominant in the hydrological cycle from 1976 to 2015. Climate change played a major role in affecting runoff variation before 2000, and then human interference dominated. It is worth noting that temperature increases resulted in runoff reduction and induced more changes in streamflow when precipitation was high. Vegetation greening contributed highly to streamflow attenuation, and its impact on runoff variation was more significant after 2007. Generally, understanding the effects of temperature increases and vegetation greening on streamflow is important for the development of appropriate adaptation strategies for the planning and management of regional water resources.