Urban Flooding Mitigation Techniques: A Systematic Review and Future Studies

Yinghong Qin

doi:10.3390/w12123579

Abstract

Urbanization has replaced natural permeable surfaces with roofs, roads, and other sealed surfaces, which convert rainfall into runoff that finally is carried away by the local sewage system. High intensity rainfall can cause flooding when the city sewer system fails to carry the amounts of runoff offsite. Although projects, such as low-impact development and water-sensitive urban design, have been proposed to retain, detain, infiltrate, harvest, evaporate, transpire, or re-use rainwater on-site, urban flooding is still a serious, unresolved problem. This review sequentially discusses runoff reduction facilities installed above the ground, at the ground surface, and underground. Mainstream techniques include green roofs, non-vegetated roofs, permeable pavements, water-retaining pavements, infiltration trenches, trees, rainwater harvest, rain garden, vegetated filter strip, swale, and soakaways. While these techniques function differently, they share a common characteristic; that is, they can effectively reduce runoff for small rainfalls but lead to overflow in the case of heavy rainfalls. In addition, most of these techniques require sizable land areas for construction. The end of this review highlights the necessity of developing novel, discharge-controllable facilities that can attenuate the peak flow of urban runoff by extending the duration of the runoff discharge.

Highlights

Most of rainwater reaching the ground surface either infiltrates the soil or returns to the air by evaporation and evapotranspiration
We found that 353 of the downloaded papers fell marginally on the topic of urban flooding mitigation, and that about 14 papers were replicated
We found that mainstream techniques for urban-flooding mitigation included green roofs, non-vegetated roof, trees, permeable pavements, water-retaining pavements, infiltration trenches, rain barrels, rainwater tanks, bioretentions, soakaways, and underground tanks

Summary

Introduction

Most of rainwater reaching the ground surface either infiltrates the soil or returns to the air by evaporation and evapotranspiration. Runoff from open soils in urbanized areas is increasing because construction activities have compacted soils to behave like impermeable surfaces [3,4]. Engineered facilities such as gutters, channels, and pipes are built to convey runoff from sealed surfaces to centralized detention ponds, retention facilities, and nearby streams as quickly as possible. In heavy rainfall, these facilities usually fail to compete with the superimposed peak flows discharging from different sealed surfaces, leading to overflow and flooding [5]. On-site stormwater treatment approaches are termed as Integrated Urban Water Management [6], Water Sensitive Urban

Methods

Findings

Discussion

Conclusion