Ecohydrology on the upsurge: history and prospect of its theory and application

Ecohydrology is a new branch of water science developed in the second half of the 20th century． Ecohydrology now faces both great opportunities and challenges, to follow President Xi’s instruction of “prioritizing ecological conservation and pursuing green development”．Ecohydrology provides principles and knowledge to alleviate contradictions between human activities and ecosystem degradation, and for “green,high-quality, sustainable” development．In this paper development and research trends of ecohydrology are reviewed． Theoretical thoughts are reviewed, including connotation and evaluation of water demand and water consumption of ecosystem, harmonious relationship and collaborative change among human-water-ecosystem, comprehensive thought of “The Four Equilibria”, Budyko water heat balance connection equation, importance of green water in ecosystem, research at both macro and micro scales in climate change．Applications of eco-hydrology (such as coupling mechanism of water-carbon cycle process, environmental impact assessment of the South-to-North Water Transfer Project and eco-hydrology issues in ecosystem and environment governance of the Yellow River basin) are analyzed．The West Route of South-to-North Water Transfer Project is an important project in the construction of national water network and is an important measure to alleviate the shortage of water resources in the Yellow River basin．Needs for eco-hydrology research were put forward. These include response mechanism of ecosystems to human activities and climate change, comprehensive technical approaches on soil and water conservation and ecosystem rehabilitation, advanced techniques of multi-source information fusion, enhancement of systematic research on ecosystem and of integration research with social science．