Master´s thesis defense by Zhenhua Sun – Niels Bohr Institute - University of Copenhagen

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Master´s thesis defense by Zhenhua Sun

Rapid urbanization has dramatically changed natural landscape. The changes in land surface cover from permeable soil cover to impervious surface result in increased stormwater runoff. In addition, losses of green natural space exacerbate this risk through decreases in rainfall collection and subsequent evapotranspiration. Applying sustainable urban drainage system and green infrastructure for runoff management provides promising solutions to increased stormwater runoff. Few studies, however, have explored the quantification of environmental benefits of stormwater runoff reduction provided by urban green infrastructure.

This study using ArcGIS 10.1, SWMM as well as the Simple Method addresses the gaps in information and methodology to quantify environmental benefits of stormwater runoff reduction by urban green infrastructure. The results demonstrated that green infrastructure plays a role in reducing runoff volume and pollutant removals. The more green infrastructure applied, the more effective it is in reducing stormwater runoff. Compared with scenario 1 in which no green infrastructure is deployed, baseline current scenario reduced 28% total runoff over two and half years. Scenario 2 shows an even higher reduction in runoff of 62% due to more applied green infrastructure.

Furthermore, green infrastructure also plays a crucial role in removing pollutant. 22% pollutants were removed from the baseline current scenario. These benefits offset the disadvantage of the overflow from a conventional combined sewer system. Therefore, the combination of conventional drainage system with green infrastructure is a more practical solution dealing with the problems associated with stormwater runoff. This study will contribute to the understanding of the role that urban green infrastructure play in regulating stormwater runoff.

Key Words: Green infrastructure, stormwater runoff reduction, pollutant removal