Abstract:In order to reduce the environmental and ecological problems induced by water resources management and use, this paper proposes a concept of ecological water requirements (EWR). It is defined as three grades for EWR, including critical EWR, optimal EWR and saturation EWR. Critical EWR are the water regimes needed to maintain vegetation growth at a low level of risk. Optimal EWR are the water regimes needed to maintain ecological function of vegetation at a continuable level. Saturation EWR are water regimes...