Effect of baffled water-holding garden system on disposal of rainwater for green building residential districts

Abstract

With the acceleration of human urbanization process and the changes of hydrological cycle in cities, urban rainfall runoff pollution has become a problem and should be solved as soon as possible. Based on the concepts of enhancing infiltration rate of rainwater and reducing runoff pollutants in source area, a baffled water-holding garden system for processing rainwater in green building residential district was developed. The system was characterized as a gridized water-holding area which was composed of baffled guide walls and barrier strips. Collected rainwater overflowed into the next sub-water-holding area from the former. During the running process, rainwater was permeated into ground and retained in sub-water-holding areas; hence, rainwater energy was reduced gradually. Furthermore, runoff erosion to plant-growing area was buffered effectively. This system can effectively control runoff pollution, reduce runoff volume, and prolong the rainwater runoff confluence time to reduce downstream peak flow. The design method of baffled water-holding garden system was described through a case study. The results in this case showed that the ratio of water-holding area and confluence area was 1:48, and the reduction rate of peak flow was up to 50%. The control rate of annual rainfall runoff volume can reach 83.7% in case area, correspondingly, the removal efficiency of TSS of annual runoff was estimated by more than 83.7%.

Keywords:

• Green building
• Rainwater
• Low-impact development
• Baffled water-holding garden
• Design method

Acknowledgements

The work reported here was financially supported by the State Water Pollution Control and Harnessing of the Major Projects (People’s Republic of China, Grant No. 2010ZX07320-001).