Some people may think that our world, through our built infrastructure, is more connected digitally and physically than ever before: we have Facebook and WeChat on the one hand, and ubiquitous highways and pipelines on the other. But actually, the opposite is true. More than ever, we are disconnected from the communities we belong to, and we have alienated ourselves from our neighbours.
Physically, the landscapes that we inhabit are Visibly interconnected: motorways connect urban and rural settlements; power lines that transport energy connect power stations to individual families; pipelines that drain waste water connect our toilets to sewage treatment plants; aqueducts that transport drinking water connect reservoirs to our kitchens airlines that transport food connect the farm in the southern hemisphere to the refrigerators in the north; trucks that carry fertilizers and herbicides on the highways connect city factories in the east with the peasants who farm in the rice paddies in the mountainous west. We have created a connected world. but these connections are false: the landscape matrix and its invisible processes are fragmented and disconnected. The movement and cycles of water, nutrients, food energy, species, and people are broken. The interconnected relationship between air, water, soil, nutrient, species, and people is being interrupted, and in a harmful way, more than ever before.
We build water treatment plants to remove the nutrients that could be used in fertilizers for farming; billions of dollars are spent yearly on the construction of concrete dikes, dams, and pipes to control floods and stormwaters, but these structures eventually produce fiercer droughts declines in groundwater levels, and habitat loss; a thousand- mile-long aqueduct built to divert water from Southern to Northern China caused serious damage to the ecosystem in the lower and middle reaches of the Yangtze River ornamental gardens and landscapes as well as agricultural fields are over-fertilized and all those nutrients flushed into the water system, polluting the rivers and the lakes. And again, the conventional solution is single-minded-build expensive water treatment plants that need huge amounts of energy (mainly from coal burning) to operate, which in turn create more air pollution.
An alternative solution might be the construction of green infrastructure, or ecological infrastructure(El) based on the timeless interdependence between peasants and their farmlands. The work includes field-making, irrigating fertilizing, growing, and harvesting. In particular, the cut and-fill approach during field-making forms an integrated action of creating earthworks onsite for farming requiring only minimum labour and transportation costs, thus causing minimum impact on the natural processes. Farmers over thousands of years ago have used this same method to transform unsuitable land into productive and livable land.
Secondly, using gravity to irrigate the field and manage the water. Thirdly fertilizing the land by reusing the materials of human living. All wastes from humans and domestic animals as well as vegetative materials are recycled into fertilizers.
Such a nutrient cycle is broken in our urbanized and industrialized settings What peasants call fertilizers are today defined as "pollutants" in our lakes and rivers.
The fourth category of peasantry wisdom is growing and harvesting. Unlike planting and pruning in gardening to create a pleasant ornamental form, the peasant's approach to planting is focused on productivity.
Planting begins with the sowing of seeds, and the management process follows nature's rhythm as a strategy of adaptation to the surrounding climate and conditions. The self-sufficient nature of ancient agricultural economies requires each household to grow diverse crops, including grains, vegetables fibers, medicines, fruits, timber, fuel, and even fertilizer proportionately to the seasonal needs of the family, and within the limits of nature.
Harvests are productive in terms of their capacity to enrich the soil, purify he water, and make the land healthy. In other words, the peasant's fields are net producers instead of net consumers of energy and resources.
Despite celebrating the return to a romanticized farming existence, it doesn't mean one should give up the comfort of urbanization and go back to a peasant's primitive life.
Imagine, imagine, imagine
Imagine what our cities would look like if we did not drain the rain water away through pipes and pumps, but instead used the a ncient wisdom of peasantry in field-making to create a green sponge in the city that retains the rain water, creating diverse habitats and re-charging the aquifer. In this way, the green spaces in the city become an ecological infrastructure that provides multiple ecosystem services that regulate the urban environment to be resilient to flood or drought, allowing clean water and food to be produced right in the middle of the city. Biodiversity would be enhanced dramatically; urban residents would have a green network for jogging, commuting, and relaxing; and real estate values would increase because of the beauty of, and access to, nature! We have been attempting to transform cities into such a sponge city since the last 20 years.
Imagine what our cities would look like if we abandon the high and rigid concrete flood walls and instead create vegetated terraces at the river banks that adapt to the ups and downs of the water flow. Eco-friendly solutions like ponds and low weirs are designed to slow down the flow of water and let nature take time to nourish itself, so that diverse habitats can be created that enrich vegetation and wild life, allowing nutrients to be absorbed by the biological processes!
Imagine what our cities would look like if the nutrient rich (eutrophic) river and lake water could be cleansed through the landscape as a living system, in the way that peasants have recycled organic waste, instead of using expensive sewage plants to remove the nutrients. We could produce clean water and nourish the lush vegetation Imagine what our cities would look like if the brown fields of industrial sites are recovered by the processes of nature, where the ancient wisdom of the pond-and- dyke system is adapted to create a terrain that collects rainwater (instead of draining it away through pipes)and initiates the evolution of a plant community, remediating the contaminated soil during this process.
Imagine what our cities would look like if we turn some of the urban land back into productive landscapes instead of into expensive lawns or ornamental gardens, so that the long-distance transportation of food can be reduced.
'Art of Survival'
By integrating this wisdom with contemporary sciences and arts, we are able to build alternative infrastructures namely nature-based green infrastructures to replace the conventional grey infrastructures. This will be able to solve some of the problems in today's urban environment particularly around water, which are difficult or very expensive to solve through conventional means. Living with nature is inexpensive and easy, comfortable and beautiful, and an art of survival."
In short, the "sponge city" comprises features that provide solutions to urban inundation in many cities. They include stormwater management, flood resilient planning and design, water quality improvement, aquifer recharge brownfield restoration, habitat restoration, greenspace creation, and urban microclimate regulation. It is ideally integrated with the construction of the cultural heritage network and the recreational network.
The urban inundation refers to severe water-related problems such as water shortage, pollution flooding, urban waterlogging, lowering of underground water tables, and loss of aquatic habitat. These are caused mainly by climatic factors, rapid urbanization leading to excessive exploitation of water resources and water pollution; and unscientific engineering-oriented measures leading to degradation of the water system.
Urbanization and construction of grey infrastructure result in destruction of vegetation. soil erosion, increased impervious surfaces, fragmentation of the water system, interruption between surface water and groundwater, change in hydrological conditions (e.g. runoff flow) acceleration of water flow at confluences and a rapid increase in flood peak value.
The past five decades have witnessed drama tic change in runoff of rivers, and the construction of dams has led to significant decreases in discharge from most rivers. For example, the completion of Three Gorges Dam led to all kinds of problems including a dramatic drop in biodiversity, more severe pollution, eutrophication of the backwater area of the reservoir, reduction in fish numbers, and deterioration of the living environment of aquatic species.
Despite that, many are still keen to resort to single-purpose engineering-oriented measures, for example, building single purpose "grey" infrastructure, to solve complex and systematic water problems. The result: water problems become worse and enter a vicious cycle. When the water ecosystem becomes imbalanced, problems arise.
Therefore, the solution does not lie in a river or its water, but in the environment beyond the water itself such as constructing hydro ecological infrastructures on multiple scales.
Sponge City concept
Every inch of urban land has the ability to retain, mitigate and purify rainwater, which is the basis for the "sponge city" concept Sponge city" is the integration of various technologies from all civilizations. They include contemporary ecological design wisdom of water adaptive technologies from ancient times and modern advanced stormwater management technology including Low Impact Development(LID) technology, water sensitive city planning.
Water is the key to design such ecological infrastructure.
In short, a Sponge City is a city built on water-centred eco-infrastructure. It’s idea is to retain water, slow down water flow clean the water by nature and be adaptive to water-totally opposite to the conventional solution of grey infrastructure.
In the past two decades, through practical projects, Turenscape has developed and tested the sponge city strategies in many large-scale pilot cases with great success.
The negative approach
The single most important basis for urban development planning is population projection, upon which urban land use resources allocation, functional zoning and built infrastructure plan are based. In most cases, the population projection for the long term (20 years) and even for the short term(5 yea rs) is never correct or even nearly correct.
In addition, the shift from a planned central economy to a market one weakens urban planning power. It has been widely recognised that the conventional economic oriented approach to urban development planning has failed. For many years, the major driving force of urban development has been road infrastructure and the developed urban area.
Urban growth is defined by the built and grey infrastructure (such as roads, power lines sewage pipes, etc). This has largely contributed to the degrading ecological conditions and the current chaotic situation in Chinese cities.
Instead, a 'negative approach’ should be used - instead of giving priority to the architectural development and built infrastructure, the 'negative approach reverses the process and gives priority to the planning of the Ecological Infrastructure(El). EI comprises the critical integrated landscape elements and ecosystems that secure essential ecosystems services
It is argued that the first and most important principle for a better urban development is determining where not to develop. The key in the 'negative approach' is planning El and its subsequent application to shape the urban growth.
The negative approach can be more fashionably described in the context of landscape urbanism, which Charles Waldheim (200637) described as: "a disciplinary realignment in which landscape replaces architecture as the basic building block of urbanism".
1. The Feng-shui model
The pre-scientific model of the negative approach' is the Chinese ancient art of geomancy, or Feng-shui, which always gives priority to the natural pattern and processes of Qi (or breath). Ordering from large to small, the whole national landscape (mountains and water courses was considered as an interconnected dragon vein and a network of Oi movement
Since the late 19th century, parks and green spaces have served as the fundamental infrastructure to solve urban problems such as congestion and sanitation in the US. As a counter-balance to urbanization, greenways are affordable because linear parks require a small amount of land, when compared with large non-linear open spaces. They can also be woven into the urban fabric with minimal disruption.
The European concepts of a green belt, green heart and green wedge have been used by urban designers as stoppers, separators and connecters of urban development to create a n arbitrary good urban form. But they have failed due to:
a) They are usually planned artificially and arbitrarily, and lack the intrinsic relationship between green elements and the living earth system;
b) They usually only serve as barriers to stop the processes of urban sprawl, and they lack the integration of various functions such as flood control, recreational use, heritage protection and habitat protection;
c) They quickly become development opportunities when peripheral pressure increases, or because they are based on political boundaries and not on natural features they become vulnerable to land use change and effectively became a bank' into which undeveloped land is held until development pressure demands its use.
By using minimum space, the EI will safeguard the critical ecosystem services including, amongst others: 1) To retain the stormwater as much as possible to recharge the aquifer, while protecting the city from the threat of floods and waterlogging;
2) To protect critical native habitats, and build an effective biological framework to maximally safeguard the biodiversily;
3) To maximally protect fertile land from being swallowed by the urban development while not impeding the urban growth.
It is argued that the current urban growth model in China is unsustainable. Recognising this fact, the Chinese leadership is now calling for ecological civilisation, a totally new concept proposed in the Chinese language and particularly worded by the top Chinese leader.
Beijing City was the first Chinese city to apply this approach followed by Shenzhen City and Chongqing City.