Abstract

Low-impact development (LID) aims to retain stormwater at source sites rather than achieve water drainage. The infiltration and storage of rainwater on site is the most commonly applied LID design concept, turning impervious pavements into pervious pavements. In this study, three field sites in Taipei city, Taiwan, were monitored. Two of the sites were located on campuses, and one site was a roadside location. They were constructed at different times and had distinct purposes, but the common design aspect was the infiltration function of the ground surface. We monitored the water retention performance at the above three sites and applied a verified stormwater management model (SWMM) to characterize the performance at these case sites. The observed data show that if the accumulative rainfall was lower than 20 mm, the water retention rate at each of the three case sites reached almost 50%; at 60 mm rainfall, the rate was 40%. With increased rainfall amount, the water retention rate decreased because the storage capacity was limited. Because water retention is typically controlled by the infiltration capacity, the rainfall intensity dominated the performance. At the three field sites, the water retention rate was 40% on average at a rainfall intensity below 20 mm/h. Above this rainfall intensity, the infiltration performance of the pervious pavement decreased. The verified model was applied to assess the performance at the three sites under the Taipei city drainage system design standard, i.e., the five-year recurrent period storm level, at 78.8 mm/h. The results demonstrate that the water retention rates were 9.1%, 14.2%, and 61.0% at the three sites, indicating that the pervious pavement could reduce the loading of the current stormwater drainage system. Dispersed sites should be considered in urban stormwater management to mitigate flooding risk in urban areas.

Highlights

  • Urban stormwater management is important for citizens

  • An effective drainage system facilitates the quick drainage of rainfall runoff to avoid possible flooding

  • The application of various infiltration or storage facilities to retain the increased runoff generated from impervious grounds could reduce the urban flooding risk, and this idea has been widely implemented in many cities

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Summary

Introduction

Urban stormwater management is important for citizens. An effective drainage system facilitates the quick drainage of rainfall runoff to avoid possible flooding. Under high urbanization, more buildings and roads are built. The loss of the water-retaining function of soil in urban areas changes the hydrologic cycle and increases the runoff quantity [1]. By increasing runoff volume and flow rate, conventional concentrated and large-scale drainage systems might be limited in their adaptability to dynamic changes in urban surfaces and climate conditions [2,3]. Runoff retention at the source has become a mainstream method. The application of various infiltration or storage facilities to retain the increased runoff generated from impervious grounds could reduce the urban flooding risk, and this idea has been widely implemented in many cities

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