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项目面积：2 298 800 m2
Project Address: Jinnan District, Tianjin
Site Area: 2,298,800 m2
Project Entrustor: Tianjin Haihe Education Park Investment and Development Co., Ltd.
Designers: Tianjin Yuanjing City Development and Design Planning Co., Ltd., Tianjin Urban Planning & Design Institute, and Tianjin Jingyi Environmental Landscape Design Co., Ltd.
Design Team: Huang Jingtao, Chu Junmin, Tian Tian, Wang Yu, Wang Xianzhe, Zhang Lu, Ma Jian, Guo Lijun, Huang Jian, Zheng Yan, Huang Minrui, Zhang Jinsheng, Yan Han, Liu Yang, Liu Jian, Wang Yang
Design Time: September 2011 - July 2012
Completion Time: April 2015
In the past 30 years, resulting from the rapid economic and social development, the irrational use of resources and the continuous expansion of construction land, the Beijing-Tianjin-Hebei Region has become an "severely afflicted ecological area". With reference to authoritative reports, over 95% of Plain River channels in Hebei Province have dried up with 90% of wetlands have disappeared . Shortage of surface water cannot conduce to the rapid development of high-water consuming industry and agriculture. Large-scale groundwater exploitation has triggered problems such as land subsidence, seawater backflow, and increased land salinization; the "pie-shaped" spread and development of the city has resulted in serious water and soil pollution and flooding of the city. The increasingly worsening ecological environment problem has endangered the regional and even national ecological security. Since the 18th National Congress of the Communist Party of China, Beijing, Tianjin and Hebei have attached great importance to ecological coordinated governance as a national strategy. It has become the core goal of Beijing-Tianjin-Hebei ecological coordination to reshape regional landscape ecological security pattern and achieve regional sustainable development.
As a significant part of regional ecological pattern, green corridor not merely carries landscape functions such as greening and recreation, but is provided with ecological functions such as flood control for safety, climate regulation, biodiversity protection, etc. The landscape design of the green corridor should not be confined to the construction of the landscape system of the green corridor itself, but should explore the technical means to address the regional ecological problems and reshape the regional ecosystem from the viewpoint of the regional landscape ecological security pattern.
1 Project Background
Situated in the green ecological barrier area between two cities of Tianjin, Tianjin Haihe Education Park is a key area for Tianjin Municipal Government to boost the ecological coordination of Beijing, Tianjin and Hebei and achieve high-quality green development. Currently, by reason of the influence of the geographical and climatic conditions in coastal areas and the disorderly expansion of cities over the years, the ecological degradation in the area is serious and the ecological environment desperately awaits to be enhanced.
1.1 Historical Evolution of the Site
From the late Middle Holocene to the early Late Holocene, the coastline on both sides of the east Haihe River of Tianjin pushed eastward from the Zhangguizhuang-Jugezhuang Line (3800 years ago) to the Junliangcheng-Nigu Line (2500 years ago) . Along with the vicissitudes of time, changes of mountains and valleys, and human settlement and regression, the middle reaches of Haihe River, where the site is located, are all situated in this sea regression area. In the 1880s, to address the problem of salt and alkali, local farmers artificially excavated the Machangjian River and introduced the sweet water from the upper Loess Plateau. The sweet water was used to brush the alkali and turn the alkali into fat, forming unique growth conditions for high-quality rice. Xiaozhan Town in the Southern Suburb of Tianjin is famous for its specialty Xiaozhan rice, which can be said to be the product of regional ecological coordination. Nevertheless, since the 1970s, due to the construction of the upstream reservoirs and the increase of water for industry and agriculture, the upstream inflow of water has been continuously reduced, and Xiaozhan rice has gradually decreased until it disappears. The paddy field surrounding the Xiaozhan rice planting area where the site is situated is also deteriorating day by day, presenting a landscape pattern of half field and half water today.
1.2 Ecological Crisis in Lands of Sea Regression
As a place of sea regression, the site and surrounding areas are facing common ecological problems in coastal areas. First, the annual average evaporation in the area where the site is situated is over 3 times of the average precipitation, and the rainwater is mostly concentrated in summer, triggering the problem of waterlogging in summer and drought in winter. Apart from that, the urban development has split the original abundant water veins in the site, and the site is threatened by serious rain and flood. Second, there exist the problems of difficult planting and raising trees arising from saline soil and high surface water. The investigation reveals that the PH value of the soil in the site is between 8.1 and 8.5, the buried depth of the underground diving still water level is only 1 meter to 2.5 meters, and the growth of trees is rather difficult. Currently, trees are only distributed in high-lying areas on both sides of roads and rivers. Third, the overall terrain of the site is relatively low-lying, with the elevation of most areas ranging from 1.6 meters to 3 meters, with an average elevation of only approximately 2 meters. To guarantee the safety of rain and flood and the growth of vegetation, greening construction requires more foreign soil and the landscape cost is generally high.
1.3 Status and Scale of the Site
Haihe Education Park, where the project is situated, is on the south bank of the middle reaches of Haihe River between Tianjin's downtown area and Binhai New Area. The park is positioned as China's vocational education reform and innovation demonstration park, Tianjin demonstration zone for research&development and innovation of high-end science and technology, and ecological livable demonstration community on Haihe south bank. The park is subject to the layout structure of "one corridor and two wings". The central ecological green corridor runs through the middle of the park from north to south, with an average width of approximately 800 meters. The project area is situated in the middle section of the central ecological green corridor, between Tianjin University and the new campus of Nankai University. It is the hub of the park's ecosystem and is also the intersection and key point of the main axis of urban development and the north-south ecological corridor. The total landscape area of the project is approximately 2,289,800 square meters, of which the land area is approximately 1,452,700 square meters and the water area is approximately 837,100 square meters (Figure 1).
2 Challenges and Goals
As a vital node of regional ecological coordination, how to address the rain and flood problems faced by the park development, reshape the landscape ecological security pattern of ecological units and integrate it with the regional landscape ecosystem; how to address the ecological problems such as saline-alkali soil in the sea regression areas, decrease the construction cost and shape the characteristic landscape style from the sea regression areas to the rice planting area and then to the mixed area of dry land fish pond; as the central ecological corridor of the education park, how to create ecological and functional interaction with the two-wing campuses and urban living areas to enhance the attractiveness of the project over talents; facing the balance between the short-term construction economy and the long-term urban growth demand, how to achieve the sustainable economic and social development is both the short-term and long-term challenges the project faces.
In consideration of the above problems, the design team has proposed 4 core design goals.
1) To combine the green corridor landscape with the construction of large-scale ecological units in a bid to achieve the organic integration of the construction of new urban areas and the regional landscape ecological security pattern, setting a good example for the construction of green ecological barrier areas.
2) To address the ecological problems in coastal areas, explore the technical means to reshape the landscape ecological pattern premised on interpreting the characteristics of regional landscape and shape the landscape environment with the characteristics of northern water villages.
3) To connect the history and future of the site, inherit the local agricultural civilization, facilitate the cultural exchange on campus, achieve the harmonious unity of natural ecology and urban life, and boost the revival of regional culture with landscape.
4) To lower the cost of park construction and sustainable operation in the near future, and reserve space for the long-term development of the region and build a low-carbon, efficient, economic and sustainable landscape system.
3 Design Strategies
With a view to achieve the above-mentioned design goals, the project landscape design, proceeding from the regional landscape ecological security pattern, proposes to restore wetland ecology and reshape the regional ecological pattern, and to solve the ecological problems in the process of urban growth and maintain ecological security by employing technical means such as terrace land technology to address saline-alkali problems; simultaneously, it comes up with the design concepts of landscape leading to cultural revival and park cultivation to create productive landscape, in a bid to address the comprehensive problems of urban development and achieve the coordinated symbiosis of society, economy and ecological environment.
3.1 Repair the Hydrological System of Wetlands, Construct Ecological Infrastructure and Reshape the Regional Ecological Pattern
Landscape ecological security pattern is a multi-level, continuous and complete network, including macro-level land ecological security pattern, meso-level regional ecological security pattern and micro-level urban and district ecological security pattern. Haihe Basin in Beijing-Tianjin-Hebei Region is a relatively perfect ecosystem with a variety of natural elements, of which the mountains, water, forests, fields, lakes and seas are a community of life. The landscape ecological security pattern is premised on a composite ecological tree network structure with water network as the framework and multiple elements such as landscape pattern, river system, wetland system, greenway system, etc. (Figure 2a). Main rivers in the basin form the main branches of the ecological tree network. Secondary water networks and ecological corridor systems are divided into different levels to enhance the structure of the ecological tree network. Large wetlands and significant ecological construction units form the fruits of the ecological tree network.
The project is situated at the northern end of the green corridor of the Weinanwa Wetland in the green ecological barrier area between two cities of Tianjin. It is a significant component of the secondary ecological tree network of the river basin and forms a large ecological construction unit covering an area of approximately 20 square kilometers in conjunction with the development areas on its two wings (Figure 2b). In the design, the central ecological green corridor and its ecological units are planned as a whole. Tianjin University, Nankai University and several higher vocational schools and other development plots along the two wings of the green corridor will build a ring-shaped school-protective river. The school-protective river will be linked with the river and lake systems of the central ecological green corridor to form a network system of wetland rivers (Figure 2c). Besides, through the surrounding backbone river networks of Hongni River, Weijin River and Dagu Drainage River, it will be integrated into the ecological tree network structure of river basin to form significant ecological fruits in the ecological tree network structure of Haihe Basin.
On the one hand, the wetland river network system in the park can be regarded as an ecological infrastructure system, which can purify and collect rainwater from surrounding plots, enhance the capacity of regulating and storing rainwater and flood, and solve the problems of summer waterlogging and winter drought in the region in combination with the traditional gray infrastructure system. Simultaneously, all the irrigation and landscape water bodies in the park can be replenished with rainwater through the construction of the water circulation system, saving 360,000 tons of water annually. On the other hand, the blue-green interweaved sponges create waterscape spaces with different scenes in combination with the construction of the greenway system with the water network, becoming the framework of the park landscape recreation system (Figure 3).
3.2 Use Local Terrace Land Technology to Address the Saline-alkali Problem and Shape the Wetland Lake Island Landscape
Since the Ming and Qing dynasties, to address the problems of salt and alkali, rain and flood, farmers in Tianjin coastal areas have, after a long period of interaction between man and nature, produced a regional local landscape system - terrace land. In the early stage of the design, the landscape system of the terrace lands around Beiyang park village on the north side of the site was studied, and the benign interaction mechanism between this ecological agricultural system and the regional landscape ecological pattern was summarized (Figure 4): digging into ponds, seeping alkali and discharging salt to control the underground water level; filling the soil into a platform to prevent the soil from returning salt and alkali; planting trees on the platform and building villages, forming dry land agriculture, wetland agriculture and ecological wet areas in turn between the high platform and the pond. In the rainy season, collecting rainwater into wetland fish ponds to avoid flooding; during the dry season, the collected rainwater will make up for villages and farmland.
The project creates a landscape style with regional characteristics by drawing on the traditional wisdom of local terraced landscape technology and combining agricultural production experience with urban ecological restoration. In light of the current conditions, in the site with an average elevation of 2 meters, while retaining some of the field corridors, the low-lying areas will be deepened based on local conditions to form wetlands and lakes, with the normal water level controlled at approximately 1.2 meters; through the self-balancing of earthwork, terrace lands are built in areas with high topography, forming low hills of different heights, with the highest point reaching 16 meters, creating wetland lake island landscape with landscape intention (Figure 5).
With a view to avoid the influence of saline-alkali soil and underground saline water on vegetation, trees are planted in areas with elevation above 2.5m; from the high tree planting area to the low wetland and lake area, a mixed ecological landscape system of forest land and aquatic plants takes shape. Solving the problem of saline-alkali by the local terrace land technology can raise the survival rate of vegetation and decrease the cost without using engineering measures of salt removal. Statistically, over the four years since the park was built, the survival rate of trees has reached above 95%, and the cost per square meter of the park is only 174 yuan.
3.3 Help Farmers to Manage Water and Build Parks, Construct Schools, Boost Culture and Revitalize the City, and Landscape will Drive Cultural Revival
As the main agricultural planting area in southern Tianjin, the area where the site is situated has a long history of agricultural civilization. While inheriting the local agricultural skills, the design preserves and enhances the farmland texture between Hongni River and Tianjin University, manages water and builds fields, and plants trees and manages farms so as to create a compound and ecological urban leisure agriculture corridor (as displayed in Figure 6). It transforms the reserved farmland into an urban orchard, expands the undergrowth economy premised on agricultural production, develops agricultural experience and popular science education activities, offer re-employment opportunities for local farmers, and also furnish space for new residents to experience local culture. Besides, it constructs an experiential scenic zone along the west side of Hongni River, organizes regular urban activities such as horticultural exhibitions and design competitions and enhances the vitality of the city and boosts regional development through public artistic events.
As the central green corridor of the education park, the project area also carries the functions of intercollegiate communication and public services. The design has reserved a 2000-meter-long standard canoe track in the central lake area between Tianjin University and Nankai University, thus furnishing water sports venues for schools and the city. Meanwhile, part of the development land has been reserved in combination with the subway station. The long-term plan is to build Tiannan Town, which will set up a platform for academic sharing and service sharing between the two schools. In the cooperation and competition between the two schools lasting over 100 years, it will bring innovation and development to the new urban area.
3.4 Construct Productive Landscape, Cultivate the Park with Parks and Coordinate Ecological Construction and Sustainable Development of the City
Based on the development schedule, the project will commence the construction of ecological green corridor in the early stage, and the employment and residential population will gradually increase following the successive development of two-wing plots in the later stage. The growth and change of the city require that the park be able to furnish a flexible structure, giving priority to the function of ecological conservation in the early stage and gradually turning to the function of urban services in the later stage. Thus, the project has introduced the design and operation strategy of productive landscape. Small-scale dense planting of trees in the early stage avails cost control, and it is estimated that the investment will be saved by approximately 50 million yuan in one lump sum; through thinning seedlings in the medium and long term, approximately 260,000 adult trees will be produced in the ten years to come, with a total estimated revenue of over 200 million yuan, which can be used to subsidize the cost of sustainable construction and maintenance of the green corridor. In the future, in cooperation with the long-term development of the city and the concentration of people, mature undergrowth space will be used to implant urban leisure places in a bid to achieve the co-growth of landscape functions and urban functions (Figure 7).
The project was initiated in 2010, commenced in 2012 and completed in 2015, and up till now, the cultivation of ecological environment has begun to produce preliminary results. The compound landscape of forests, fields and aquatic plants has formed a multi-layer vegetation habitat from xerophyte to aquatic, furnishing a habitat for biological communities and effectively repairing the wetland ecosystem. The regional landscape ecological security pattern is reconstructed by planning the green corridor landscape and the open space system in the development areas on both sides as a whole ecological unit, thereby realizing the effective management of rain and flood and the recycling of water resources. Landscape, as an ecological infrastructure, will be built first and gradually boost the development of the park; currently, the park has built 13 colleges and universities, assigned 12 residential plots, and served over 150,000 people, initially strengthening the attraction towards talents and the promotion of regional value.
As an ecological unit in the ecological tree network of Haihe Basin, the project has fully excavated the terrace land landscape system of the region, built a micro landscape ecological security pattern of the park, and effectively connected with the regional landscape ecological security pattern of the basin where it is located. The project exploration of park building methods such as terrace land technology, rain and flood management, flexible growth and productive landscape has endowed certain referential significance to the ecological restoration practice of Tianjin and even the Beijing-Tianjin-Hebei ecological coordination circle. Nevertheless, in other landscape environments, since the natural geography, social economy and human interference modes are different in different basins, the environment compositions of landscapes are not entirely the same as well. Therefore, it is necessary to rebuild a micro landscape ecological security pattern suitable for the local environment after having made a profound interpretation of the characteristics of its regional landscape. Apart from that, relevant policies and systems for ecological coordination at the basin level should be worked out in view of management organization, management and control system, fund raising and ecological compensation, in a bid to guarantee the smooth implementation of regional ecological environment management.