  Sponge city construction is a new concept of urban stormwater management,
which can effectively relieve urban flooding, reduce non-point source
pollution, and promote the usage of rainwater resources, often including the
application of Low Impact Development (LID) techniques. Although 30 cities in
China have been chosen to implement sponge city construction, there is a lack
of a quantitative evaluation method to evaluate the environmental, economic,
and social benefits of LID practices. This paper develops a comprehensive
evaluation system to quantify the benefits of different combinations of LID
units using the Storm Water Management Model (SWMM) and the Analytical
Hierarchy Process (AHP) method. The performance of five LID design scenarios
with different locations and sizes of the bio-retention facility, the grassed
swale, the sunken green space, the permeable pavement, and the storage tank
were analyzed for a sports center project in Guangxi, China. Results indicated
that the green scenario that contains 34.5% of bio-retention facilities and
46.0% of sunken green spaces had the best comprehensive performance regarding
meeting the requirements of 75% annual total runoff reduction and the
attainment of good operation performance, rainwater utilization, landscape
promotion, and ecological service functions, mainly because they are
micro-scale and decentralized facilities that can manage stormwater at the
source through the natural process. The optimal scenario was adopted to
construct the project, and the proposed evaluation system can also be applied
to optimal selection and performance effect evaluation of LID practices in
other sponge city projects.
