Permeable pavement (PP) systems provide opportunities to mitigate the impacts of urbanization on receiving water systems by providing at source treatment and management of stormwater. However, they do not receive mainstream use throughout much of Canada and the USA because of a lack of local guidance documents, demonstration projects and performance data. Studies have repeatedly shown that PPs attenuate stormwater flows by reducing volume and frequency of stormwater flows, reducing and delaying peak flow rates, and increasing flow durations. PP systems have been shown to improve stormwater quality by reducing stormwater temperature, pollutant concentrations and pollutant loadings of suspended solids, heavy metals, polyaromatic hydrocarbons, and some nutrients. This review is intended as a comprehensive summary of the current state of knowledge of the environmental performance of PP systems. Published research is synthesized to examine the hydrologic performance, impacts to water quality, longevity and functionality and maintenance needs of PP systems. Where appropriate, the limitations of current knowledge are discussed and emerging and future research needs are presented. The intent of this review is to provide stakeholders in stormwater management with the critical information that is needed to foster acceptance of PPs as a viable alternative to traditional systems.

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Review of environmental performance of permeable pavement systems: state of the knowledge

This review paper presents, in a critical and systematic way, the published researches on water-sensitive urban design (WSUD) technologies and practices. The aim of WSUD is the long-term sustainability for urban water cycle management; it minimises the hydrological impacts of urban development on the surrounding environments. It considers stormwater as a valuable resource. The applications of WSUD technologies in practice could be the solution of everyday problems of small-scale stormwater management—flood control, pollution control and stormwater harvesting. This paper focuses on the recent research outcomes of several frequently used WSUD technologies including infiltration systems, permeable pavements, bio-retention systems, vegetated swales and rainwater harvesting systems; their barriers and adaptations; and future research directions.

A review of water-sensitive urban design technologies and practices for sustainable stormwater management

As of 2010, more than half of the global population resides in urban areas and relies to some extent on the functions, services and natural capital provided by urban soils. Greater extremes in climate predicted for the coming decades will impact on these urban soil functions to varying degrees. We provide an inventory of urban soil functions based on an extension to the typology of the Millennium Ecosystem Assessment (i.e. we added a carrying function to those of supporting, regulating, provisioning and cultural) and review the climate drivers which are likely to have the most significant impacts upon them, using urban soils of England as an exemplar. We identify knowledge gaps, in areas such as carbon cycling and storage, disease regulation and cultural services. We assess adaptation measures which may ameliorate these potential, climate change-related impacts including changes in construction practices, developments in green architecture and development proposals under the planning regime. We discuss the lack of policies relating to urban soils and the problem associated with monitoring their functions, as is often the case, when large quantities of soil are removed and replaced leading to major transformation of soil properties which may be un-related to pedogenic processes.

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A review of climate change impacts on urban soil functions with examples and policy insights from England, UK

To mitigate the impacts of impervious surfaces in urban areas, structures such as bioretention systems and permeable pavements have been installed to enhance infiltration in many countries. However, relatively little knowledge is available regarding the performance of such infiltration-based structures in humid tropical and highly urbanized areas. This study investigates the feasibility of enhancing the infiltration of stormwater in tropical urbanized areas using Singapore as a case study. It first shows that the rainfall depth and intensity are both high, but the time interval between consecutive rainfall event is long in Singapore. It then numerically simulates single-event local infiltration and finds that the fraction of infiltrated rainfall is actually high. It finally performs catchment-scale simulations and finds that bioretention systems can enhance infiltration and groundwater recharge particularly during wet periods. However, local mounding of groundwater can be significant and can hinder the performance of those structures. Furthermore, with 5% of catchment area being converted to such structures, the infiltration of the entire catchment is enhanced but still not yet up to the natural level. To increase the overall effectiveness, future studies can look into bioretention systems with underdrain systems. Copyright © 2016 John Wiley & Sons, Ltd.

Modelling infiltration enhancement in a tropical urban catchment for improved stormwater management

In every city, low-volume roads and parking lots are composed of dense-graded pavements that increase storm-water runoff; however, urban flooding problems can be prevented if an appropriate pavement system is achieved. One preferable solution to this problem for low volume roads and parking lots is to use permeable interlocking block pavement. To determine the storage capacity of this kind of pavement, a series of material property tests were performed such as specific gravity, void ratios, and porosity etc., which was further used to calculate the water storage capacity of the pavement. And rainfall simulation tests were performed to evaluate surface runoff, delay time, storage capacity, and outflows over two hours. A regression analysis showed that the water storage capacity measurement from rain simulation tests agreed with the storage capacity calculation depending on laboratory materials-properties tests, based on their high correlation and coefficient values, each within the 95% confidence interval.

A case study: Evaluation of water storage capacity in permeable block pavement

Impervious surfaces have long been implicated in the decline of watershed integrity in urban and urbanizing areas. Porous pavement is one solution to mitigating the problem of stormwater runoff problems. In this research, three available porous pavement systems were investigated to evaluate their infiltration capability of precipitation. Experiments were conducted to simulate different kinds of porous pavements having different sub-base materials in different cells. The discharge volumes were monitored from each cell, and the relationship between rainfall intensity, outflow and outflow duration was analyzed. Results show that these three porous pavements increased infiltration and decreased runoff. The optimum thickness of the porous pavement was 31 cm, which consisted of a 6 cm top layer of porous concrete and a 25 cm sub-base (10 cm concrete without sand and 15 cm aggregate base). Furthermore, under a rainfall rate of 59.36 mm/h, the runoff coefficient of the above porous pavement was zero, while the coefficient of the impervious pavement was 0.85. These results provide a clear indication of the value of porous pavement systems for broad expanses of the human engineered environment.

S. Feng

Papers

Experimental study on rainfall-runoff relation for porous pavements