Sponge Cities

Introduction

"The Sponge City philosophy is to distribute and retain water at its source, slow down water as it flows away from its source, clean water naturally and be adaptive to water at the sink when water accumulates – this is in stark contrast to the conventional solution of grey infrastructure, which is to centralize and accumulate water using big reservoirs, speed up the flow by pipes and channelized drains, and fight against water at the end by higher and stronger flood walls and dams.[25][32][33] The theory of Sponge City emphasizes the basic principles of 'based on nature', 'source control', 'local adaption', protecting nature, learning from nature, preserving urban ecological space as much as possible, restoring biodiversity, and creating a beautiful landscape environment. All of this can be realized by achieving natural absorption, natural infiltration, and natural purification.[25][34] 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.[2][5] The infiltration effects of the natural ecological background (such as topography and landforms), the purification effect of vegetation and wetlands on water quality, and the combination of natural and artificial means allow the city to absorb and release rainwater. Urban green spaces and urban bodies of water —constructed wetlands, rain gardens, green roofs, recessed green spaces, grass ditches, and ecological parks—are the central "sponge bodies."[34][35]

There are three main facets to developing such systems: protecting the original urban ecosystem, ecological restoration, and low-impact development.

Sponge city policies have been more frequently implemented in new construction than in retrofitted developments from the past few decades of rapid urbanization." - Wikipedia: Sponge City 

Other Names

Chinese: 海绵城市

Benefits of Sponge Cities

Better Water Quality

Run off and ambient pollutants in cities and other communities can become a big danger to local drinking water, with the pollution load increased during heavy rains. Not only does a sponge city reduce the load of water and pollutants, but the plants used help to filter out pollutants.

Flood Prevention & Reduction

Flooding can be reduced or prevented, including flash flooding or prolonged periods of rain.

Significant Money Saved

Drought Protection

Reduced Heat Island Effect

Increasing the amount of green infrastructure while reducing the hard surfaces including metal and concrete can massively improve urban temperatures, reducing deaths as well as energy use.

Reduced Impact on Transit

Floods can destroy cars and other vehicles. Trains and buses can be delayed or suffer other issues due to flooding, but defensive infrastructure like sponge cities can help prevent this type of impact.

Problems of Sponge Cities

Costs

Upfront Cost of Implementation

Maintenance Costs

Features of Sponge Cities

Many flood and drought resilience solutions can be included in a sponge city. Some of the following are frequently implemented, while others are suggestions that may be appropriate to certain cultures or climates.

Private Property Scale

These include solutions for buildings and gardens, meaning schools, hospitals, government offices, homes, and businesses could all implement these to compliment solutions at larger scales.

Blue Roof

These harvest rain water for future use which could include garden care or hand washing and toilet flushing.

Green Roof

These use plants and growing mediums to capture rain water, and boost local biodiversity. Green roofs can also help insulate against heat waves and cold winters. Instead of adding to heat domes, they can help reduce urban temperatures.

Rain Garden

These specialized flowerbeds use water-loving and drought-resistant plants to help capture, clean, and absorb rainwater. They are not sealed like ponds, which allows water to enter aquifers instead of contributing to flooding.

Rain Storage Systems

Sustainable Drainage Systems

(Community Level)

These are generally designed into the local infrastructure at the community or neighborhood scale.

Watershed Scale

 Riparian Areas

Wetlands

Existing Sponge Cities

Asia

Bangladesh

China

"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.[8][9][10][11] Though the concept had been published and practiced since early 2000, it was the Beijing flood on July 21, 2012 which caused 79 deaths that prompted the top Chinese authorities to accept the Sponge City concept and make it a nationwide policy.[10][12][7] In 2015, China was reported to have initiated a pilot initiative in 16 districts.[13][14][15] This initiative presents an alternative to solve Asia's flood problems. China seeks to curb its flood with the initiative. The country plans for 80 percent of its urban cities to harvest and reuse 70 percent of rainwater."  - Wikipedia: Sponge City 

Europe

Germany

North America

USA

California

Tools & Apps

North America

USA

Minnesota

Maps

International

Europe

UK

Organizations

Europe

UK

North America

USA

New York

Grants & Funding

North America

USA