China has one of the world's biggest populations and largest economies. This has created some of the most dense cities on Earth. When all of these are placed together, it's understandable that when a problem occurs, it effects a lot of people and has an extremely large impact.
China classifies cities within three levels, totaling 662 cities. Of these 662 cities, approximately 400 are said to have some form of water shortage, of which 110 have severe water shortage. Of China's 32 mega cities (which Dictionary.com defines as having population over 10 million), 30 have various water supply problems.
One reason of the water shortage is that the natural water cycle is interrupted by the conversion and occupation of nearby forests, lakes, grasslands, and wetlands for urban development. Adding to the issue is the barrier of natural storm water replenishment, blocking it from reaching ground water storage, further causing flooding. The People’s Republic of China (PRC) reported in 2010 that 351 cities were affected by urban flooding. These and otherchallenges, including unsustainable urban development, are causing “groundwater over-extraction and waterway degradation”.
Fang and Li, two researchers on this topic, wrote "Case Studies of the Sponge City Program in China" where they state “The new sponge city construction aims to help Chinese cities with water shortage situation to avoid the forest, lake, wetland occupation and breaking the natural water cycle”, by using permeable surfaces and green infrastructure. Currently the Sponge City (SPC) concept has 16 pilot projects started in April 2015 with plans to have 30 by 2030.
Sponge City and Low Impact Development
Sponge Cities (SPC) promote water security, water environmental protection, and water ecological restoration. The development started in 2013 and the research is focused on Low Impact Development (LID) practices and other storm water management concepts as well as Sustainable Urban Design Systems (SUDS), Water Sensitive Urban Design (WSUD), and Low Impact Urban Design and Development (LIUDD) practices.
The best outcome of the SPC concept is that one of it's overall processes absorbs storm water, stores it, then filters and cleans it through natural or engineered facilities, creating water that can be reused afterwards. The initiative also changes the current way of thinking by using storm water as a resource, using it in natural flows (like rivers) for urban development, so that city development can adapt and become resilient to climate change.
China’s Sponge City initiative is very ambitious with goals that by 2020, 80% of the urban areas should absorb and reuse at least 70% of rainwater.
The SPC is similar to the North American LID, which tries to mimic natural processes in order to protect water quality. SPC tries to do that by evenly distributing absorption capacities.
The construction of SPC is divided into three different parts: urban natural ecological protection, ecological restoration, and LID system construction. To have an effective SPC implementation, the measures that have been implemented need to have a sustained effort which includes environmental governance. Concerns for the sustainability of these projects lies within the lack of regulations and weak enforcement.
Additional challenges to SPC include sustainable financing, which can also be an issue for the projects. According to CNN, $12 billion has been spent on all SPC projects, of which the central government funds 15-20%, with the rest of the funding coming from other parties in local governments and the private sector. It was also identified that investments in SPC are hard to find as there is a lack of support from the government on improving conditions to increase current investments “...including tax incentives, better project transparency, and looser credit markets.” This is shown in Wuhan, where the governmental subsidies will only continue until 2020, then the city has to find own investors to sustain and maintain the project, which places pressures on the lack of legislation.
Sponge Cities in China
According to The Guardian, current SPC projects require 20% surface space through 2020, with project guidelines expanding it to 80% by 2030. By 2030, China wants to expand the SPC concept to include a total of 30 projects.
Lingang, part of Shanghai's Pudong District, works with Sponge City concepts in a collaboration with city regulators, engineers and property owners. Seen as one of their prime pilot projects with investments mounting over $119 million, Lingang is seeing great successes with the concepts such green rooftops, wetlands for rainwater storage, and permeable pavements to store excess water.
There are key learnings that are coming from the SPC concept that also could help other cities in the world that are suffering from water problems from urban design. The concept is an opportunity for China to show its leadership role in urban sustainability developments. Let's see what the future will bring regarding this topic.