1. INTRODUCTION
Along with rapid urbanization, the proportion of world urban residents
is expected to increase from 56.2% in 2020 to 67.2% in 2050 (DESA,
2018). It was estimated that global urban landscape area has increased
by 19.1 million hm2 between 1985–2015, and
approximately 70% of the newly urban landscape witnesses in Asia and
North America (Liu et al., 2020). Unprecedented rate of global
urbanization, whose most significant feature is the natural and semi
natural surface being replaced by the impervious surface, causes a
series of ecological challenges, such as urban flooding, urban heat
islands, air pollution, and loss in natural habitat (Kulmala et al.,
2020; Oke et al., 2017; Grimm et al., 2008; Foley et al., 2005). Urban
flooding, refers to the fact that the heavy rainfalls overwhelm the
capacity of self absorption and drainage pipelines drainage. Urban
flooding causes great economic losses, and even kills the urban dwellers
(Rentschler et al., 2022; Paprotny et al., 2018). It was reported that
more than half of the world’s population was affected by flooding from
2010 to 2019. China suffered from the flooding with 400 events
contemporaneous. Meanwhile, global warming is likely to exacerbate urban
flooding risks (Touma et al., 2022; Debele et al., 2019). Thus, how to
reduce urban flood loss is of great significance to urban
sustainability. Fortunately, a series of practices have been conducted,
such as “best management practices”, “low impact development”, and
“sponge city construction” (Davis et al., 2005).
Urban flooding has attracted more and more attention for its frequent
occurrence and severe damage (Kim et al., 2022; Lin et al., 2022; Ma et
al., 2022; Chen et al., 2021; Sun et al., 2021; Yang et al., 2021;
Paprotny et al., 2018). Previous related studies have tended to reveal
urban hydrological mechanism by adopting field investigations,
laboratory modeling and urban hydrological modeling (Ma et al., 2022;
Shrestha et al., 2022; Li et al., 2022; Muthusamy et al., 2021). Among
these, a comprehensive understanding of the
spatial–temporal patterns of
urban flooding and its most influencing factors was vital and
fundamental (Steinhausen et al., 2022; Li et al., 2022). Urban flooding
events were significantly clustered and mainly distributed in the
central urban area (Li et al., 2022; Zhang et al., 2020). The
distribution pattern of urban flooding events can be caused by
topographic conditions (i.e.,
elevation, slope, roughness, and microtopography),
rainfall intensity,
land cover composition and
configuration, stormwater storages, and drainage systems (Hettiarachchi
et al., 2022; Li et al., 2022; Wang et al., 2022; Dumedah et al., 2021;
Liang et al., 2021). For example, Tehrany et al. (2019) found that
elevation was significantly impacted urban flooding in small catchments.
When the digital elevation model resolution increased from 50 m to 1 m,
flooding extent and mean flood depth decreased by 30% and 150%,
respectively (Muthusamy et al., 2021). However, it is difficult to alter
topographic and heavy rainfall, so more and more researches seek to
mitigate urban flooding through rational urban planning. On the one
hand, an improvement in urban drainage system was beneficial to manage
urban runoff. On the other hand, optimal blue–green–grey spaces were
also important to alter urban hydrological process and reduce flooding
risks.
Numerous studies have shown that land cover and land configuration have
direct effects on urban flooding in the horizontal (Hettiarachchi et
al., 2022; Wang et al., 2022; Li et al., 2020). However, fewer studies
have investigated the impact of buildings on urban flooding in the
vertical dimensions (i.e., building height and its heterogeneity).
Although buildings and roads may have roughly the same permeable
capacity, their roles in regulating urban runoff can vary greatly (Cao
et al., 2021). Specifically, building height and building coverage ratio
alter runoff generation time. Building facades increase the surface
contact with raindrops and thus decrease runoff. In addition, the
interaction effect of building and its surrounding miniature garden has
direct effects on the ground runoff. Furthermore, buildings alter its
surrounding microclimate, which has direct or indirect effect on soil
moisture and evapotranspiration. Thus, three-dimensional building
pattern might change the local hydrological process. Lin et al. (2021)
noted that adding building metrics can better explain the probability of
flooding occurrence in Shenzhen, especially the building coverage ratio.
A large number of
three-dimensional building metrics have been developed to
comprehensively characterize building patterns (Kedron et al., 2019; Liu
et al., 2017). A series of studies further explored the relationship
between three-dimensional building pattern and land surface
temperature/air temperature, air pollution. However, the effect of
2D/3D building patterns on urban
flooding remains unclear. We attempt to address the following two
questions: (1) how urban flooding events affected by
2D/3D building patterns in
megacies? And (2) does an enhancement effect exist between 3D building
metrics? Addressing these questions can promote our further
understanding on the role of buildings in urban flooding. Such
understanding can provide insights for urban flooding mitigation.