Study On Influencing Factors Of Rainwater Runoff Regulation In Bioretention Facilities

Sponge city is a new urban construction concept vigorously developed in China.To some extent,it can alleviate the problem of waterlogging in Chinese cities,at the same time,it also has the functions of purifying water quality and beautifying the environment.As a common single measure in sponge cities,bio-detention facilities are widely used,because of their simple structure and strong adaptability to the surrounding environment and geographical location.Three different external conditions including inlet hydraulic load,plant ratio and scale effect were selected.Through the simulation test of biological detention facility under different conditions.To explore the control effect and variation rule of biological detention facilities on hydrological evaluation indexes,such as total stormwater runoff and stormwater runoff peak.The effects of biological detention facilities were also analyzed.The biological retention facilities mainly about stormwater runoff.Under different hydraulic loads and different plant ratios,the biological retention system presents an change process to the stormwater runoff hydrological process.This change process are exponential growth-slow growth-stable change.The results showed that the reduction rate of total runoff was 23.3% to 100%.Secondly,the reduction rate of peak runoff was 5.6% to 100%.At last,the runoff peak delay time is18 min to 60 min.Hydraulic load can inhibit the regulation of stormwater runoff in biological detention facilities,while plant ratio can promote it.The effects of different scale biological detention facilities on stormwater runoff regulation were compared.It can be found that the total runoff reduction rate of biological detention facilities was28.5% to 100%.The runoff peak reduction rate was 6% to 100%.The runoff peak delay time was 27 min to 60 min.The larger the scale of bio-detention facilities,the better the effect of rainwater runoff peak reduction of bio-detention facilities.SPSS 24.0 software and systematic clustering analysis method were used to analyze the effect of stormwater runoff control in biological detention facilities.This biological detention facilities include hydraulic load,plant ratio and scale effect.The results show that hydraulic load has the greatest influence.Scale effects have the least impact.Therefore,hydraulic load is the decisive factor influencing the effect of stormwater runoff control in biological detention facilities.