A Green Sponge in the City – Nature-Based Solutions Benefiting Urban Planning
Grey Infrastructure and Broken Connections
The landscapes that we inhabit are visibly interconnected: motorways connect urban and rural settlements; power lines transport energy and connect power stations to individual families; aqueducts transport drinking water from reservoirs to our kitchens; trucks on highways that carry fertilisers and herbicides connect factories with farms. Supposedly, we have created a connected world. But 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. Their interconnected relationship is being interrupted, and in a harmful way, more than ever before.
In China, over 75 per cent of the surface water is polluted; 50 per cent of cities are facing floods and urban inundation; and over 60 per cent of cities do not have enough water. The groundwater table in the North China Plain drops over 1 metre each year; and over 50 per cent of the wetland habitats have been lost in the past fifty years.
All these water-cycle related issues that impact cities and landscapes are interconnected, but conventional infrastructural solutions are fragmented, isolated, and single-minded: water treatment plants remove nutrients that could be used in fertilisers. Billions of dollars are spent yearly on the construction of concrete dikes, dams, and pipes to control floods and stormwaters.
However, 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. Gardens, landscapes, and agricultural fields are over-fertilised and nutrients flush into the water system, polluting rivers and lakes. And again, the conventional solution is to single-mindedly build expensive water treatment plants that need huge amounts of energy (mainly from coal burning), creating air pollution in turn.
An alternative solution might be the construction of green infrastructure which creates a deep and true connection between man and nature and among various natural processes and flows.
The Ancient Wisdom of Farmers
One option to rebuild the deep connection between human beings and nature and among various natural processes comes from the wisdom of farming, which transformed landscapes on a large scale and sustained humanity for thousands of years.
- Making of fields through “cut-and-fill”: an integrated approach where earthworks are built on-site, with minimum costs for labour and material transportation. It has, therefore, a minimum impact on the natural processes and patterns in the region. This tactic has been implemented by farmers around the world to transform unsuitable environments into productive and liveable landscapes.
- Managing water and irrigating the fields: modern methods of irrigation don’t relate to surrounding terrain and available water resources. The traditional approach is deeply rooted in natural processes. Thousands of years of farming experience have made irrigation one of the most sophisticated techniques in agricultural societies. The use of gravity, and the harmony between nature and subtle human intervention can turn such a serious science into an art form, an interactive medium of community building, and even a spiritual force.
- Fertilising: traditional farming reuses the materials of human living, creating the kind of nutrient cycle that has been broken in our urbanised and industrialised settings. What used to be called fertilisers is today defined as “pollutants” in our lakes and rivers.
- Growing and harvesting: Unlike planting and pruning in gardening focussed on creating a pleasant ornamental form, the farmer’s approach to planting is focussed on productivity. Harvests are productive in terms of their capacity to enrich the soil, purify the water, and make the land healthy. In other words, the fields are net producers instead of net consumers of energy and resources.
All of this is not to say that one should give up the comfort of urbanisation and go back to a traditional life. But these features propose a basis on which to rebuild the connections between nature and human desires, balancing natural processes and cultural intervention, and help to reclaim the harmonious relationships between human beings and nature.
Imagine What Our Cities Would Look Like
To promote sustainable urban development, we could make use of the ancient techniques of field-making to create a green sponge in the city. Instead of draining the rainwater away through pipes and pumps, retaining it would help to create diverse habitats and to recharge the aquifer.
Green spaces in the city could become an ecological infrastructure that provide multiple services, such as production of clean water and food right in the middle of the city, while making the urban environment resilient to flood and drought at the same time.
Abandoning the high and rigid concrete flood walls could revive the old techniques and create vegetated terraces at river banks that adapt to 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!
Instead of using expensive sewage plants, we could produce clean water and nourish the lush vegetation through the landscape as a living system and urban parks could become producers instead of consumers of energy and water.
What if the brown fields of industrial sites were recovered by the processes of nature, where the knowledge of the pond-and-dyke system is adapted to create a terrain that collects rainwater and promotes a plant community, remediating the contaminated soil. At the same time, the industrial structures are preserved as sites of cultural heritage. A unique landscape is created, featuring dynamic native vegetation and a touchable memory of the past, attracting urban residents and the diverse wild life in the middle of the city.
Imagine the change if the urban land was turned back into productive landscapes instead of lawns or ornamental gardens, so that the long-distance transportation of food can be reduced. This will not only make our city more productive and sustainable but nourish a new aesthetic and a new ethics of land and food.
By reviving the knowledge of the old techniques and connecting them with contemporary sciences and arts, we are able to build nature-based green infrastructures replacing the conventional grey infrastructures. These can solve some of the problems in today’s urban environment 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. That is what we have tried to do in many cities in the past twenty years: to transform the city into a sponge city.
[This article originally appeared on Urbanet.]