Fengxi New City
Fengxi New City of Xixian New Area is located in Shaanxi province of China, close to the historic city – Xi’an, with a planning area of 143km2. It is the ruins of Fengjing of the Western Zhou Dynasty, which is the earliest city in China. Now the 46km2 of its core area is already constructed as business parks, residential areas and public spaces. Great importance is attached to green development in Fengxi New city. The green space ratio of Fengxi New city is about 50% and its percentage of greenery coverage is about 60%.
Regarding Sponge City construction, since 2011, Fengxi New City has introduced the idea of regional rainwater management and Low Impact Development into its city planning, and actively carried out research and practise. In April 2015, Fengxi New City has been selected as one of the first batch of pilot Sponge Cities by the Chinese government. Also, in July 2019, it was authorized for the global ecological demonstration pilot project of hydrology by the United Nations educational, scientific and cultural organization (UNESCO).
Meanwhile, Sponge City in Fengxi New City not only focuses on rainwater harvest and urban flooding control, but also focuses on urban public spaces construction, river protection and restoration, as well as biodiversity, just as NBS. By promoting sponge city construction in Fengxi New City, now the whole city’s ecological environment is greatly improved.
The development of green energy is another successful project of Fengxi New City . Here, the city uses deep geothermal energy to replace coal or natural gas for heating in winter, which is very environmental, green and sustainable. Now the city has compiled some standards and technical guides for the development of deep geothermal energy.
Environmental and Social Issue
The overall landform is high in the south and low in the north, and the main urban area is relatively flat. There is a large area of Ⅰgrade collapsible loess distributed in the central part. Generally, the collapsible loess of Fengxi New City is of low grade and the soil permeability is good (the average permeability coefficient is between 1×10-6m/s~3.8×10-5m/s, and the soil permeability in the western part of the central part is relatively poor). The average annual precipitation of Fengxi New City is about 520mm, within which from May to October the precipitation is relatively high, and the maximum precipitation happens from July to September. In summer, the precipitation is mostly in the form of heavy rain. Fengxi New City has a short duration (120min) rainstorm type, which is mainly characterized by front type single peak rainfall (rain peak coefficient r=0.31) (figure 53). Therefore, it is suitable to adopt the source dispersed low-impact development measures for runoff control. All the residential areas and business parks in Fengxi New City has been built with sponge city concept. Rain garden, bioretention zone, permeable sidewalk, roof gardens can be seen everywhere. Fengxi New City has three mail rivers. Now thanks to the sponge city construction and other river restoration measures, all the rivers are protected and with clean water, very beautiful scene and rich biodiversity. Fengxi New City is located in semi-arid and semi-humid continental monsoon climate zone. Due to sponge city construction and NBS, the city’s heat island effect is not serious.
Although the government of Fengxi New City attach great importance to NBS planning, yet there is lack of professional knowledge in NBS planning and implementation. Also, the operation and maintenance of sponge city and NBS is also difficult. There is lack of good experience and guidance. Currently, Fengxi New City promotes the concept of sponge city throughout the entire city, and it has completed a lot of successful projects, including sponge neighborhoods, roads, parks and other public service projects. Urban drainage and water-logging prevention capacity has been significantly improved, and the quality of the water environment has continued to improve.
Fengxi New City is working to toward building an integrated energy system, to build a lower-carbon, more ecological, sustainable and healthy city. As to accessibility by public and private transport, Fengxi New City will be built with small blocks and dense road network, and intercity railway, subway and intelligent rail transit will be constructed with TOD9 (transit-oriented development) mode, to integrate transportation hub, business, catering and other life service functions and to build a green and low-carbon city. Fengxi New City will also comprehensively promote advanced technologies such as passive buildings, healthy buildings and prefabricated buildings, with a view to build an ideal city model that integrates city and people, city and ecology harmoniously.