Ecological water requirements in urban ecological restorations

With water shortage aggravating, problem of poor water quality and eco-environmental deteriorations in rivers and lakes is becoming more serious．Seasonal river flow is almost completely off during dry season, not counting discharges of waste water．Therefore, eco-environmental water supplementation is an important measure in urban watershed ecological restoration project．However, some uncertainties remain regarding the actual supplemented water flow, to avoid either insufficiency or overflow waste of water resource．Characteristics of staggered river channels and ponds, seasonal differences in water requirements, are all taken into account to computate accurate water requirements．A comprehensive ecological hydraulic method is proposed for ecological water requirements of river channel, converting functional requirements of river channel into hydraulic constraints, to obtain ecological flow based on hydraulic simulation of channels．A functional method is used to calculate ecological water requirements of ponds．Ecological water requirements of rivers and ponds in different seasons in Jiudaoyan water ecological restoration project in Chengdu were then calculated．Comprehensive determination of water supplementation in urban watershed ecological restoration project as proposed in this paper is of important reference value to protect water ecology and environment．