Assessing the Use of Dual-Drainage Modeling to Determine the Effects of Green Stormwater Infrastructure on Roadway Flooding and Traffic Performance

Kathryn L Knight,Suren Chen,Aditi S Bhaskar,Guangyang Hou

doi:10.3390/w13111563

Abstract

Green stormwater infrastructure (GSI) is increasingly used to reduce stormwater input to the subsurface stormwater network. This work investigated how GSI interacts with surface runoff and stormwater structures to affect the spatial extent and distribution of roadway flooding and subsequent effects on the performance of the traffic system using a dual-drainage model. The model simulated roadway flooding using PCSWMM (Personal Computer Stormwater Management Model) in Harvard Gulch, Denver, Colorado, and was then used in a microscopic traffic simulation using the Simulation of Urban Mobility Model (SUMO). We examined the effect of converting between 1% and 5% of directly connected impervious area (DCIA) to bioretention GSI on roadway flooding. The results showed that even for 1% of DCIA converted to GSI, the extent and mean depth of roadway flooding was reduced. Increasing GSI conversion further reduced roadway flooding depth and extent, although with diminishing returns per additional percentage of DCIA converted to GSI. Reduced roadway flooding led to increased average vehicle speeds and decreased percentage of roads impacted by flooding and total travel time. We found diminishing returns in the roadway flooding reduction per additional percentage of DCIA converted to GSI. Future work will be conducted to reduce the main limitations of insufficient data for model validation. Detailed dual-drainage modeling has the potential to better predict what GSI strategies will mitigate roadway flooding.

Highlights

The increase in impervious surfaces characteristic of urbanization leads to higher peak runoff and total runoff volume in receiving water bodies [1]
The results described above indicated that the conversion of even 1% of the directly connected impervious area (DCIA) to green stormwater infrastructure (GSI) lead to the reduction in mean roadway flood depth and spatial extent, and increasing the amount of GSI added to 5% of the DCIA further reduced the mean roadway flood depth and spatial extent (Figures 5 and 6)
Modeling stormwater structure-scale interaction between green stormwater infrastructure (GSI), surface runoff, and stormwater networks to examine the extent, depth, and distribution of 2D roadway flooding within a watershed is critical for expanding the understanding of how GSI impact urban systems such as transportation networks

Summary

Introduction

The increase in impervious surfaces characteristic of urbanization leads to higher peak runoff and total runoff volume in receiving water bodies [1]. These effects of urbanization indicate a loss of the watershed’s ability to naturally mitigate flooding and must be compensated for by the implementation of stormwater management practices [2]. These stormwater management practices are commonly inadequately sized, designed, or maintained to mitigate the frequency and magnitude of floods in urban watersheds [3,4]. Survey data from across the United States found that urban flooding outside of established floodplains is common and urban flooding disproportionately affects lower-income communities [6]

Methods

Results

Discussion

Conclusion