Water & Wastewater Asia September/October 2021

ENVIRONMENTAL REPORT
STORMWATER
management
Vincent Lee, global water skills leader at Arup’s New
York office, highlights how the company’s study of
New York’s impervious area will help the city better
understand and manage the impact of stormwater.
New York City, the most populous city in the US
To effectively manage water across an entire
city, it is important to properly understand
the environment it sits within – and crucially
where the water will go when it rains.
It was with that in mind that the New
York City Department of Environmental
Protection’s (DEP) Bureau of Environmental
Planning and Analysis (BEPA) sought out
Arup’s expertise to develop a city-wide
impervious area geographic information
system (GIS) layer. Put in its simplest terms,
it was a study to help the DEP understand
the make-up of the land across the city, and
identify which areas will soak up water, and
which impervious areas it will simply run off,
and potentially cause flooding problems.
New York City is commonly referred to
as a “concrete jungle” due to thousands
of square miles of impervious surfaces.
However, a significant amount of work has
been done by the city in reducing these
surfaces which cause significant flooding.
One such programme is the NYC Green
Infrastructure Plan from 2010, which set a
course to manage stormwater much more
effectively and sustainably.
Photo credit: Triston Dunn/Unsplash
While an impermeability map was prepared
over a decade ago, there have been
significant advances in data, map resolution,
and remote sensing techniques. Arup’s work
was to provide this information – in forensic
detail – and ensure DEP could continually
update this crucial water management
data going forward. This would enable
DEP to validate their programme and also
provide a defendable source of data that
DEP can use to drive stormwater policy to
improve the quality of the city’s waterways
while reducing the flood impacts in its
neighbourhoods.
FOUR-STAGE PROCESS
The task essentially had four stages –
research, mapping, interrogation of what the
information gathered, and finally ensuring
the process was one the DEP would be able
to update and maintain in future years.
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