Right in the middle of the city of Sanya and in just three years, an area of lifeless land fill within a concrete flood wall has been successfully restored into a lush mangrove park, where nature and people harmoniously share the meeting of ocean tides and fresh water. The project demonstrates the success of following the ecological processes of wind and water that produce a designed ecotone made of inter-locked fingers to speed up the natural process of mangrove rehabilitation.
Site and Challenges and Objectives
Three decades of ruthless development has left Sanya，a tropical tourist city in China’s Hainan Island, a mess of destruction in terms of landscape. Almost all waterways in the developed districts have been polluted and filled with garbage. Concrete flood walls were built to claim land for development that killed the mangroves, wiped out the riparian habitats, and blocked tides from the sea and storm water from the upper land causing urban inundation. Meanwhile, increased population, particularly seasonal tourists and immigrants are demanding more connected parks along the rivers, which were sadly inaccessible. In 2015, the city government decided to make dramatic changes, and the landscape architect was called upon to design this demonstration project: Sanya Mangrove Park.
▼原始场地分析，the pre-existing conditions
The site is 10 hectares in size, on the east bank of Sanya River that bears the name of the city itself, and in the central area of the city. Analysis shows that the site is also critical in terms ecological relationships between the sea and inland, where the daily sea tides meet with the fresh water of the river. Typical of the city, the water is polluted due to the urban runoffs. High concrete walls have enclosed about 10 hectares of land that is filled with urban debris for a new development project that has been stopped by the government.. An artery road runs by, and there is a 9 meter steep drop from the road to the water, challenging public access to the water.
▼可抵御热带风暴的混凝土结构，one of five pavilions of modulated concrete that are designed to be resistant to strong tropical storm
The design objectives are to rehabilitate the mangroves and make the site a park showcase for citywide urban renewal and ecological recovery. Several site challenges have to be addressed: (1) Wind–the strong annual tropical monsoon storms may harm the process of mangrove rehabilitation and destroy the fledging mangrove planting; (2) Water– the upper stream floods from the monsoon storm water may wash away the young mangrove community; (3) Pollution: The polluted urban runoffs may damage sensitive mangrove seedlings and the biodiversity of the mangrove community; (4) Access: public accessibility and natural restoration need to be well integrated.
▼修复后的红树林公园，the established mangrove park
Design Strategies：Form follows processes
In addressing the above site challenges and to achieve the project objectives, the following design strategies were taken:
Balanced earth work: the land fill composed of urban construction debris and concrete materials from the demolition of the flood wall are recycled on site, and by means of cut-and-fill, ecotones of water ways and riparian habitats of various elevations are created for diverse fauna and flora, particularly different species of mangroves;
▼丰富的驳岸生态系统，an eco-system with diverse fauna and flora
Inter-locked fingers: a land form of inter-locked fingers was designed to lead ocean tides into the park. This is necessary for the mangroves, but they must at the same time avoid annual strong tropical storms from the sea and the storm water flood and pollution from the upper stream mountain and urban area that may harm the establishment process of the mangrove community. This also maximizes the edge effects (water edge length increases 6 times from 700 meters to over 4000 meters) and habitat diversity with water depth varies from 0 to 1.5 meters, and creates a dynamic aquatic environment following the rise and fall of tides, which are necessary for some aquatic species.
▼指状相扣的地形把海潮引进公园，the land form of inter-locked fingers was designed to lead ocean tides into the park
Terraces and bio-swales: Making use of the 9-meter drop from the urban road to the water level, terraces are integrated with bio-swales to catch and filtrate the stormwater from the urban pavement and road, creating public spaces at different elevations.
▼台地和生态廊道，terraces and bio-swales
Adaptive design of pavilions and access: a network of pedestrian passageways follow the landform. A skywalk is designed as a ramp to create an experience of walking above the mangrove canopy; five pavilions are strategically allocated allow visitors to enjoy the tranquility and beauty within the mangroves, as well as providing necessary shelter and shading in the changeable local weather. The modulated concrete shelters are designed to resist strong tropical storms; they open to views from various angles. The twisted pavilions make good shelters for bird watching.
▼景观盒子被布置在林间幽静景美的位置， viewing pavilions are strategically allocated in the landscape
▼模块化的混凝土盒子能抵抗强烈的热带风暴，the modulated concrete shelters are designed to resist strong tropical storms
▼遮荫挡雨的空间，a shelter preventing the visitors from sun and rain
This project is a great success. Just three years after its construction, its objectives have been fulfilled. The mangroves within the interlocked fingers have established well. Along with the flourishing mangroves, fish and birds are abundant, attracting visitors of different ages. The park has become a daily recreational place for the local communities, and a showcase of ecological restoration that not only benefits the natural environment, but the public welfare. Just as the slogan on one of the pavilions says: blue water and Green Mountain is essentially Gold Mountain.
▼市民的日常活动场所，a daily recreational place for the local communities