Study On The Ecological And Environmental Water Demand Of Beijing Section Of Chaobai River

Chaobai river is the second longest river in Beijing with abundant water resources and is one of the most important drinking water source of Beijing.However,the excessive development and prolonged drought seriously damaged the ecological environment of Chaobai river and the safety of water supply of Beijing.Therefore,the research on the ecological environment water demand of Chaobai river is of great significance to the ecological environment restoration of Chaobai river.Based on the latest version of comprehensive treatment planning research in Chaobai river basin,the river was divided into six research areas.For each area,the ecological characteristics were analyzed and three goals of the ecological restoration at different levels were determined including the present level,the lowest level and the highest level.The ecological water requirement under different goals was then calculated for each study area.According to different water demands and control conditions for ecological restoration,the ecological environment water demand can be determined as three types:the discharge control,the water amount control and the water level control.Tennant method was selected for the discharge control type,vegetation quota method was selected for water amount control type and water balance method was selected for water level control type.Results showed that the ecological and environmental water demand of Chaobai river(in Beijing)was about 42 million m~3 at present level.The water demand was more than 300 million m~3 for the lowest level and was more than 475million m~3 for the highest level.The results indicated that the available water resource in Chaobai river basin can satisfy the goal of ecological restoration at present level.However,there still existed a big gap for the lowest level of ecological restoration.Finally,an assumption of water resources allocation in the future was discussed.The discharge of Chaobai river can be recovered by connecting the water systems,the recycling water,the rainfall,and the increasing inter-basin water transfer.