R E S E A R C H @ H K U S T
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Fragrant Harbor 2.0
Cities are already home to 50% of the
global population. Within two decades,
this figure is expected to rise to 60%,
or five billion people. Mitigating the
impact of urban activities on the
hydrosphere – oceans, seas, lakes,
rivers, and other water bodies – and
the monitoring and management of
municipal water systems are major
concerns for a sustainable future.
Water pollution control in densely-
populated coastal cities is a particularly
challenging
task
that
demands
innovative technology, as the coastal
waters in such urban settings typically
have multiple beneficial uses.
Hong Kong has proved a significant
location
for
water
environmental
engineers to contribute globally to
understanding and technologies related
Knowledge breakthroughs are building platforms for technologies that
can assist eco-friendly water quality management, reveal problems in pipelines,
and revolutionize wastewater treatment
Natural and polluting discharges in
the environment exist as buoyant jets –
wastewater effluents from cities and
industry, thermal discharges from power
stations, virus-laden plumes in the
atmosphere, and hydraulic jets in civil
engineering structures. The effluent
discharge is mixed by the turbulent
vortices in the environment, leading to
a continuous and rapid reduction in
pollutant concentration. Predictive model-
ing of buoyant jets provides a basis for
environmental management and control,
enabling impact and risk assessment,
definition of mixing zones, the design of
advanced effluent diffusion systems to
meet water quality objectives, real time
water quality management (for example,
control of disinfection dosages), and public
engagement for better understanding of
the impact of infrastructure projects.
Back in the swim after
Hong Kong’s major harbor
cleanup. Hong Kong has a
compact urban area yet also
encompasses a 700-kilometer
coastline and 1,700 square
kilometers of diverse marine
waters, which have served
as a “big laboratory” for
testing designs and solutions
to mitigate many water
pollution issues arising from
the city’s industrialization and
population pressures.
Photo: Sam Tsang /
South China Morning Post
to the environmental hydraulics involved
in such issues. The city’s spectacular
harbor (the name Hong Kong means
“Fragrant Harbor” in Chinese) and many
beautiful beaches have been a focus of
attention, with the community goal of
cleaning up the water pollution problems
left over from its past role as the world’s
workshop from the 1960s to 1980s and
sewage treatment needs of its rapidly
rising population.
Fathoming Buoyant Jets
For Prof Joseph Lee, the first Asia-based
academic to receive the Hunter Rouse
Hydraulic Engineering Award from the
American Society of Civil Engineers,
the theoretical understanding and
mathematical modeling of the mixing of
buoyant jets has been a core area over his
35 years of research.
SMART SOLUTIONS FOR
WATER MANAGEMENT
