THE PHILOSOPHY OF THE SPONGE

Sponge City is a vivid description of an urban form, and the philosophy, and methodology of stormwater management and flood control practice.

Sponge City is a kind of eco-city based on ecological infrastructure. The eco-infrastructure is different from traditional gray infrastructure of which is single targeted and mechanically constructed. It's an integrated service-oriented ecosystem, by employing ecological principles, landscape architecture approaches, and the key techniques of infiltration, storage, purification, utilization and discharge, to accomplish the main goal of urban waterlogging prevention and stormwater management, and to achieve the comprehensive targets such as ecological flood control, water purification, groundwater recharge, brownfield restoration, habitat protection and restoration, green parks construction and urban micro-climate regulation, etc.

Sponge City is a theoretical, methodological and technical system integrated with contemporary internationally advanced stormwater management technologies and ecological urbanism thoughts, which was put forward in the context of China's unique geographical and climatic characteristics and on the foundation of China's historic cultural heritage.

Sponge is a metaphor, refer to the elastic eco-city accumulate and infiltrate runoff naturally. It's a prudent reflection on the mechanical city construction idea in the industrial age and the errors made in water resource utilization and hydraulic system protection. This idea is critical to the simple engineering concepts, and contains sophisticated philosophy. This rebellious thoughts embodied in the following aspects (Note:The following section was first published in Landscape Architecture, 2015, 14 (2): 4-9, named as Philosophy of Sponge, and used as the preface in this book.

First, complete eco-systematic value, rather than partial utilitarian value. It only takes a little observation to find the human's selfish and pragmatic attitude towards rainwater. The workers in the brick kiln prayed for the sunny day all year long. The peasant suffered from draughts went to the Dragon King Temple to burn incense to pray for rains day after day. And the citizens treated the rain as a nuisance while the farmers regarded it as the source of life. Such a huge gap existed among human beings themselves, not to mention the alien attitudes towards rain in different species. Taking the frogs for example, the concerning and caring is wretchedly inadequate. The philosophy of sponge is focus on containment. The idea is a great challenge toward human beings' self-engrossed value in rainwater. To convey sponge philosophy is tantamount to proclaim: the rain is bestowed by heaven with its inherent value. It is intrinsically valuable to the whole eco-system, not just for some specific people, belief or species. As an organic part of the system, human beings are the inescapable productions of the eco-system and the best beneficiary of the nature. So, each drop of rain has its meaning, has its value. Sponge treasures and conserves every drop of rain.

Second, try to solve water problems on-site, rather than transferring the issue to other area. Every modern water conservancy project originated from and ended in the intention of delivering the disasters to the other places. For instance, the methods like flood control dyke and the long distance water transfer, all discharged the floods downstream or to the opposite bank, or impose the damage from draughts &water shortage to the innocent region and vulnerable communities. The philosophy of the sponge is to regulate humidness and dryness locally without shifting it. It sparked us on the brightness of adaptation, and inspired us to solve the problem on-site. In ancient Chinese survival wisdom, water is a wealthy and fiscal sign. No matter the rain from the roofs, or the runoff down the hills, they are all collected in places. This is the most convictive explanation why the water harvest tank in the farmers' household courtyard so ubiquitous and why the pond-trench systems on the majority of land in China so popular. This Sponge Landscape is our ancestors' ancient wisdom adapted to drought and flood, but also a harmonious co-existent refection of the relations in geographical society and geopolitical neighborhood. It's the experience and wisdom imprinted on earth at a price of millions of generations' sacrifice for thousands of years. Many elder members in my family lost their lives in the fight with the neighboring village. This knife fight only intrigued by the intention to lift the dam several inches up on the upstream of White Sand Stream, in order to expand the irrigation area for only a little longer miles. Therefore, the best solution to deal with the wet &dry disaster is to dig the storage pond on one' own land, and regulate the draught and flood just on-site.

Third, decentralized civil construction, rather than centralized authoritarian project. China's water conservancy projects are sets of conventional programs reflect the will of the county and community. This kind of construction works range from the water management by Dayu in ancient era to the Yangtze River dam in modern time. And this is one of the direct reasons of the origin and development of central authoritarian social system in China for thousand-years-history. In some circumstances it is necessary, such as Dujiangyan Irrigation Project, due to the conceptual and engineering wisdom of guiding the water in the light of its natural trend, the project still functioning well till today, and benefit the entire Sichuan flatland. But the failure cases in the centralized large projects are plentiful, such as, water storage dams, cross-regional water transfer projects, flood prevention weir of major rivers, centralized drainage pipe system in cities. The most typical projects are the Sanmenxia Reservoir, Aswan reservoirs, etc. From the view of contemporary ecological values, the centralized projects confronted with the natural process are both inadvisable and unsustainable. To the contrary, the decentralized or democratic folk hydraulic engineering work usually holds a better sustainability. The ancient miniature water conservancy projects scattered on vast land of China conserved intact under the good care from the villagers. Such as ponds and weirs, still full of vitality till nowadays. Very unfortunately, these historic folk hydraulic heritage once have bred the Chinese agricultural civilization was destroyed by national water conservancy projects forcibly. The philosophy of sponge is decentralization. A functional entity is made up by millions of tiny cells. It can permeate and absorb the external strength in spontaneous way. Therefore, we appealed for cherish and care to the civilian water conservancy heritage, and advocate domestic and dispersed micro-irrigation project. These decentralized civilian water management facilities contributes to the great country's ecological sponge system without any harm to the natural watershed process and pattern, but meet human beings survival and developing needs.

Fourth, slow down, rather than speed up, detain &retain, rather than discharge &blow-off. Drain the storm water as fast as possible. It's regarded as the basic philosophy of contemporary flood drainage project. So the three-facet polished watercourse is the most efficient. The straightened river way is the most scientific. Even the trees, shrub and grass on the riverbed, are bound to be removed in order to reduce the flow resistance. This fast-speed oriented guidance turns a blind eye on the systematic feature and dominant factors' value of the water pattern and hydraulic network. As a result, the destructive power of floods strengthened and devastated, the hazard shifted from upstream to downstream. Water is separated from earth, other creatures, human beings and cities. The linkage between surface water and groundwater was decreased and cut off, the underground water can't be recharged, the earth can't be moistened, and the biological habitat gradually disappeared. The philosophy of sponge is to slow the water flow down, calm it, ease it, let it no longer wild and horrifying, as well as to provide the water with the opportunity to permeate in land, nourish the life, purify itself, have more chance to serve human.

Fifth, hold on flexibly, rather than resist rigidly. Contemporary engineering flood management thoughts overlooked the classical Chinese philosophical essence--overcoming firmness by gentleness, but stick on the concept of resistance—defending resolutely. The inflexible weirs and rigid dams trussed up the rivers in China. None of them could escape the misfortunate destiny. The originally soft and meandering flow declined to rigidly straight-rowed drainage trench. Thousand-year experiences of flood-control and flood-prevent experiences tell us, if human cornered the flood by strong defense line forcefully, the floods would become fierce monsters with tremendous and unstoppable destructive power. The counterattack from spate would be impending, while the preventing dams would inevitably collapsed and destroyed. Sponge copes with external momentum through the philosophy of flexibility and Changes the resistance and confrontation into harmonious coexistence. As the saying goes, taking a step back as boundless as the sea and sky. If we advocate the philosophy of water delights the wise man, then, highest wisdom of the water might be conquering the unyielding with the yielding.

The philosophy of sponge emphasis on turning something into nothing, turning huge to small, turning the exclusion to tolerance, turning centralization to decentralization, turning fast to slow, turning hardship into softness. Sponge City becomes a major slogan for urban construction nowadays. If not to perceive and study the philosophy profoundly, the Sponge City construction could be reduced into a signboard of the vanity projects and profit-making projects by some cities, engineering companys as well as planners &designers. Besides, this practice also could avoid a new round damage towards the ecosystems of water. The founder of Taoism (Lao Tzu) once said prudently, Nature does not hurry, yet everything is accomplished, which has illustrated the essence in the philosophy of sponge.

Peking University, the School of Architecture and Landscape Design Kongjian Yu

Nov. 2015

(Translated by Zhangxu)