How do spatial factors of green spaces contribute to flood regulation in urban areas? A systematic mapping approach

Abstract

Flooding is increasing in urban areas around the world, leading to loss of life and property damage, and cities are using urban green spaces (UGS) for flood regulation. The spatial attributes of UGS have an important role in controlling and regulating urban flooding, and there is a need for a systematic map on how spatial factors of UGS, such as shape, size, location, or connectivity, impact flooding in urban areas. The objectives of this study are to analyze and synthesize published material to evaluate the impacts of the spatial dimensions of UGS on flood regulation and to identify knowledge gaps and future research directions. Pertinent literature was reviewed and synthesized using the systematic mapping method. The results of this study show that previous research on spatial configuration have examined how variables such as slope, DEM, green space coverage, and landscape shape index impact runoff reduction. Slope was found to be an important, but not determining factor in flood regulation. There is a need for further research on how the geographic context of urban regions, including climatic conditions and land use changes, impacts UGS functionality. Additionally, there is a need for further research on how the spatial configuration of UGS impacts flood vulnerability and intensity, two under-addressed yet important topics in urban flooding.

To What Extent Have Nature-Based Solutions Mitigated Flood Loss at a Regional Scale in the Philadelphia Metropolitan Area?

“…Grey infrastructure is expensive, energy-intensive, and lacks the diverse benefits of natural infrastructure-based solutions [20]. Recognizing these limitations, stakeholders, policymakers, and planners are turning to complementary solutions like natural infrastructure and NBS due to their environmental and economic sustainability [17,22]. The International Union for Conservation of Nature (IUCN) defines NBS as "actions that protect, sustainably manage, and restore ecosystems to address societal challenges, providing simultaneous benefits to human well-being and biodiversity" [23].…”

“…Drawing upon the findings of previous studies [17,25,46,48,49], two potential indicators of NBS configuration, namely the shape index (SI) and contiguity index (CONTIG), were computed, specifically tailored to assess flooding at the census tract level. This analysis was conducted using FRAGSTATS version 4.2.…”

“…However, the success of these adaptation strategies depends on their structure, including composition (the quantity and variety of NBS kinds) and configuration (the quality and spatial aspect of NBS types) to reduce flood risk in different regions [16]. Understanding to what extent NBS size within the study area and its spatial characteristics such as shape, connectivity or contiguity could mitigate the risk of flooding would help to facilitate the availability and to increase efficiency of NBS in flooding hazards and its impact [17]. County-level analyses are critical, as they provide a nuanced perspective that considers the unique characteristics and interconnectedness of urban and rural areas within a specific geographic region.…”

“…This is especially significant in rapidly urbanizing regions where a significant portion of the urban landscape is already occupied by built environments and grey infrastructure [19]. Yet, the results of previous studies at different scales, specifically regarding the configuration of NBS are inconsistent, limiting a comprehensive understanding of the role of these factors in flood reduction [17]. Hence, it becomes crucial to carefully evaluate and optimize the shape and configuration of NBS to fully leverage its potential benefits and enhance its effectiveness in addressing flooding.…”