Advances in ecological environment impacts of water trading

In the situation that social and economic development is restricted with limited water supply, water trading is one of the most effective mechanisms to solve the water resource crisis in the world. Water trading disturbs natural distribution of water resources over spatial and temporal scales, thus has both positive and negative influences on the water quality and quantity, leading to various ecological and environmental consequences. However, there are few researches on the reviews of impacts on ecological environment of water trading. In this paper we extensively reviewed large numbers of studies regarding the impacts of water trading on water resources system. Then four main research points were proposed and analyzed, i. e., tradable water and their corresponding impacts on water quality and quantity, as well as relevant aquatic ecosystems. Based on the existing research of domestic and abroad, four potential extension researches could be undertaken in the future:① the establishment of the quantitative approaches for the impacts, ② the enhancement of studies upon specific water related subjects (e. g. water quality, ground water, and return flow), ③ the illumination of multiple water trading modes and their impacts, and ④ the consideration of the inherent uncertainties of these impacts of water trading.