EMPIRICAL RESEARCH OF WATER QUALITY AND QUANTITY CONTROL EFFECT OF SPONGE CITY CONSTRUCTION: A CASE STUDY OF HEBI PILOT AREA

After the first batch of pilot cities construction completed, studies on sponge city planning and simulation increased obliviously. However, studies on continuous monitoring and in-depth analysis of sponge construction were still scarce, which were just the key to optimize the future planning and construction of sponge city. This study selected Hebi in Henan Province as the research area to analyze the characteristics of water quality and runoff reduction rate, before and after the sponge city construction. The purpose was to evaluate the effectiveness of sponge city construction on surface water quality and quantity. Manual monitoring and auto-detecting measures were used to monitor water quality and quantity in study area. From August in 2015 to September in 2018, 10 sample sites were monitored by 16 batches and 109 samples were finally analyzed. Meanwhile, flow data collected by the flowmeters of 20 rainwater discharge pipelines in 2018 were analyzed. The results were as follows: three water quality indexes, NH₃-N,TN and DO had higher variation scopes, while pH had a lower variation scope. With the construction of sponge city, water quality had been improved. The runoff reduction rate of 2018 was as high as 85.7%, meeting the expected requirements. However, rainwater was discharged into pipelines when rainfall depth was less than 23 mm. The runoff reduction rate of different parts in study area was significantly different. This study enriched the practical data for sponge city and provided support for its construction and maintenance.