Presenter: Mrs. Li Jing Jing
Co-author(s): Dr. Zou Chao Wang
Organisation: Hubei Institute of Water Resources Survey and Design
Sub-theme
4. Supporting Aquatic Ecosystem Health and Functions
Topic
4-8. Water quality improvement
Body
There is poor water environment quality in rural and urban lakes in the shallow hill water network area north of the Han River on the Chinese Jianghan Plain due to their poor hydrodynamic conditions. We herein selected ten typical rural lakes and an urban lake to simulate water environment improvement. Through the survey analysis, model simulation, joint analysis, and other methods, the amount of pollutants in the lakes were determined before and after pollution interception and control. Based on MIKE21, the hydrodynamic and water quality models are established and verified. The trend of lake water quality was simulated and compared the improvement of lake water quality was demonstrated with 3 different water diversion flow rates. The result shows that after a series of pollution control treatment measures have been taken, such as sewage outlet renovation, sewage collection and treatment, rural domestic sewage treatment project, garbage pollution prevention and control, farmland non-point source pollution prevention and control, livestock and poultry breeding pollution treatment project, water and soil loss control, urban surface runoff pollution prevention and control, lake endogenous control，the improvement rate of water pollution load after pollution treatment is more than 70%. However, lakes still fails to meet the water quality target. The replenishment of water from the backbone river to the lakes could enhance the fluidity of the rural lakes but cannot eliminate the total phosphorus (TP) risk. Therefore, in the relatively closed water bodies of rural lakes in the shallow hilly water network area, pollution intercept and control is key to controlling TP, and taking measures such as increasing lake hydrodynamic conditions in summer will be a more efficient approach to improve rural lake water quality. Typical urban lake results show that the parameters of various water quality of the lake were improved with increases recharge flow. When recharge flow increases from 10m3 /s to 20m3/s, water quality gradually increases. However, a downward trend can be observed with the improvement of increase rate. The increase rate of TP, TN, COD improvements from 10m3 /s to 15m3/s are 14.51%, 15.04% and 8.88% separately. The increase rate of TP, TN, COD improvements from 15m3/s to 20m3/s are 7.85%, 8.39% and 4.62% separately. Therefore, when a water diversion to a lake is considered for the ecological replenishment, the economics should be carefully evaluated such as the cost, implementation difficulty and improvement of the water quality etc.