Abstract: Water is a vital resource. River basins are both the key bodies of water resources and the major cradles of human civilizations. It is particularly true for China, one of the ancient civilizations and the most populated country in the world. A long-term practice shows that the development of river basins has significant polarized characteristics of ecological effects: our human society began to set apart from the natural river basins as technology to be widely used to solve all the problems of life, that civilization made human successful, but great costs to the river basins, while a serious interference and damage to the phylogenetic diversity of natural ecosystems and watersheds. The higher the basin development, the more obvious polarized effects it has. Based on an empirical analysis, this paper argues that due to the lack of a fully understanding of the polarized ecological effects and the pursuit of human development, the carrying capacities of the Yellow River Basin and the Yangtze River Basin have been facing more and more serious challenges, such as rivers no longer flow into the sea, water is polluted, wetlands are draining out and aquatic animals are diminishing. For a sustainable development of the river basins in China, there is an urgently need to change the concept from the traditional one emphasized with "Human development first, natural protection second" to a new one addressed on "Natural protection first, human development second".

Key words: big river basins, human civilization, the Yellow River Basin, the Yangtze River Basin, polarized effects