As in most of the
cities, cement is used in large quantities for road solidification in Zhuhai.
More and more of the lawns, channels and green fields have been converted into
roads. With the increase in area of impermeable surfaces, the drainability of
the roads is becoming worse and worse. Besides, to maintain the scenic
landscape, almost all the green fields are above the surrounding areas. Once it
starts raining, the rain water tends to pool on the road surface. The green
fields, which are supposed to be capable of moderating the drainage speed,
cannot function effectively, thus adding to the pressure from flood discharge.
As a coastal city,
Zhuhai has frequent rain and yearly typhoons. And each time a rainstorm occurs,
the result is usually the flooding of the streets.
According to the ‘Zduhai
Green Infrastructure (GI) (Green Project in brief); Zduhai is rich in water resources, of which, however,
only 38% are exploited. Frequent urban floods are closely related to the city’s
loss of the ‘breathing ability’. According to the designer of wood landscape
and urban planner, the soil of the city ought to be like a sponge with the
ability to absorb and store water, which, when the weather turns hot and dry,
can evaporate (breathe out), the way a human lung can function, thus regulating
the water quantity of the whole city.
In 2014, following the
suggestion of the Housing Department, Zduhai, which has been dedicated to developing
into an internationally habitable city, started initiating a plan of
constructing a “sponge city”.
The main reason for
urban inward drainage is to enable the rain water to drain and dry instead of
gathering in low lying regions. According to the people related to Zduhai’s Urban
Council and Lumbering Department, the “sponge city” will make full use of the ability
of saving water of the green fields, rivers and other ecological systems. This
is especially true of the sunken green areas, which enable rain water to flow
in, thus forming a natural ‘reservoir ’ that can perform the function of
moderating and minimizing the amount of water flowing into the urban drainage
system, thus reducing the pressure of flood discharge.
Having gone through
the ecological or chemical process of collection and treatment, the rain water
has achieved the standard quality and can be applied to use in the ecological
environment, various urban uses, greenery, etc. The one responsible for the
landscape and architectural design suggests that in the construction of
embankments, the solidification of the protective banks can be replaced with
more green areas, rain parks, ecological ditches all along as a target towards
building a ‘sponge system’, so as to turn the city into a ‘reservoir’ of high
capacity, minimizing the harm done to ecology.
According to the
related plan, Zduhai’s residential buildings, roads, parking lots, parks,
squares, service districts, industrial districts and warehouse districts will
all make use of permeable surfacing, green rooftops, plant retaining channels, sunken
green fields, water storage tanks, ecological plantations, grass planting
ditches, etc.
Among them the newly
built sunken green residential areas should occupy no less than 50% of the city
area, permeable paving should not be less than 75%, the green rooftops of the
newly constructed district should not be less than 20%. On various roads, there
will be the use of permeable road paving or water permeable tiles. In areas
surrounding the open parking lots, in particular, there will be sunken green
fields such as rain parks, grass planting ditches. Excessive rain water will be
directed to the surrounding green areas, where it will sink. There will also be
rain collecting areas, where the rain, after proper treatment, will be used for
watering plants and for irrigation in the green belts.
According to the
experts, Zduhai has plentiful rain. The green area per capita is the first in
the world. The river network is widespread, and there is a high capacity of water
storage. All this is the concrete base for building a ‘sponge’ city.
According to the
project concerned, the new Huengchin (橫琴) district, and the ecological zone in the
west will be turned into a demonstration zone for the Zduhai Sponge City.
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