Sponge city
Sponge city policies are a set of nature-based solutions that use natural landscapes to catch, store and clean water; the concept has been inspired by ancient wisdom of adaptation to climate challenges, particularly in the monsoon regions in southeastern China.
"[7] The People's Republic of China adopted the Sponge City initiative, largely motivated by the failure of the conventional grey infrastructure of flood control and stormwater management systems, due to the persistent efforts by Chinese ecological urbanists through letters and proposals sent to high level Chinese authorities since early 2000.
Unscientific architectural planning also creates a large number of buildings, simultaneously limiting cities' green space, drainage, and rainwater collection ability.
[25] Meanwhile, high-intensity artificial constructions, such as buildings, roads, and public squares, lead to the lower pad's excessive hardening, changing the original natural foundation and hydrological characteristics.
The simple concept of fast discharge, a traditional gray water management model, is no longer helpful in addressing the rainwater dilemma during rapid urbanization.
"[27][28][29] To this end, in October 2014, the Ministry of Housing and Urban-Rural Development issued "Technical Guidelines for Sponge City Construction", emphasizing the importance of the top-level design of urban rainwater management, as well as planning to guide urban construction with ecological priority as the basic principle.
In addition, the Central Ministry of Finance introduced a public-private partnership (PPP) model to increase financial policy support.
However, this set-up may threaten local government's ability to fund these programs, which are estimated to require $230 billion by 2030 in order to meet their goals.
[25][35] These principles come from long-standing wisdom and strategies practiced across China for thousands of years, when water had to be worked with and around instead of combatted with gray infrastructure.
Sponge city policies have been more frequently implemented in new construction than in retrofitted developments from the past few decades of rapid urbanization.
