宜昌黄柏河湿地公园规划设计 | 杭州园林设计院
A bird 's-eye view of the wetlands from the east © 王昱，沛林生态
A bird 's-eye view of the wetlands from the west © 王昱
A bird 's-eye view of the west side of xiaping wetland © 王昱
Rivers and cities are often in a symbiotic relationship.
Many cities have a "mother river" that bears the needs of urban residents for drinking water, agricultural irrigation and industrial development. For a long time, rivers have fed cities, but cities have not fed rivers back. On the contrary, the development and expansion of cities often brings pollution, encroachment of river channels and decline of ecological resources, resulting in frequent occurrence of problems such as soil erosion, rain and flood disasters and water resource crises.
In recent years, with the popularization of the concept of environmental protection, the contradiction between the city and the river has been gradually eased. Policy makers are also paying more and more attention to the protection of rivers, relinquishing the space that originally belonged to the river, and returning it to nature and citizens. This project is a typical case.
The project is located along the Huangbai River in Yiling District, Yichang City. It is divided into two sections, located in Xiaping Village and Caijiahe Village, with a total area of about 154 hectares, of which the water area is about 35 hectares. The adjacent Nancaixia area is the core of the future northward expansion of Yichang city, and the city is closely related to the river.
The Huangbai River is a first-class tributary of the Yangtze River, with a total length of 162km. The downstream section flows through the urban area of Yichang. It undertakes the important task of supplying water to 2 million people and 1 million mu of farmland in the urban area of Yichang and Yidong. The total economic volume in the water supply area accounts for about 80% of the city is known as the "Mother River" of Yichang. The average slope of the Huangbai River is 3.76 ‰, and the mountains on both sides are steep, which is a typical mountain stream type river. Different from plain rivers, the former has obvious seasonal characteristics. In the flood season, a large amount of surface runoff can be collected in a short period of time, and the flow rate is large, and the sand carrying capacity and scouring capacity are strong; in the dry season, the water volume decreases sharply, and part of the riverbed is exposed.
The project area is the only two floodplain wetlands of the Huangbai River passing through the urban area of Yichang, where the river suddenly widens and plays an important role in regulating stormwater and providing habitats for living things. The status quo of the wetland retains a relatively primitive natural base, with large areas of tidal flats and ponds, and some natural forests grow well in some areas. The soil and rocks are exposed, the natural vegetation is destroyed, and there are a large number of artificial facilities such as sheds, abandoned factories, vegetable fields, etc., which have a great negative impact on the natural style and ecological value.
The status quo of the site is full of traces of quarrying and sand excavation，farmland and vegetation fields，easy to cause soil erosion and non-point source pollution. © 张骞
Design Strategy - Ecology First, Minimal Intervention
The project is essentially an ecological restoration project, and its primary purpose is to protect and restore the floodplain wetlands of the Huangbai River flowing through the urban area of Yichang, so that it can better play its ecological function. Therefore, at the beginning of the design, the principle of putting ecological restoration first and "park" attributes second. That is to reduce the human damage and disturbance to the wetland, restore the vegetation, and create a suitable habitat for all kinds of wetland organisms, especially birds, so that they can live and reproduce here. The second is the needs of people, that is, to increase park facilities on this basis to meet the needs of public activities.
The minimal intervention strategy, for nature, refers to not disturbing the original area of the wetland as much as possible, such as retaining the existing native trees in the wetland as much as possible, and prioritizing the design if there is a conflict with the design. For people, it means that the boundaries of human activities should be demarcated, and the damaged wetlands should be restored.
Overall plan of the project © 杭州园林设计院股份有限公司
Master plan - classification, sorting and construction based on stormwater analysis
Stormwater analysis - a prerequisite for master plan
Huangbai River is a mountain stream type river with huge water level difference between flood season and dry season, and the design range is located in the river channel delineated by the water conservancy department. Therefore, the rain and flood factor is the first consideration in the design. It is necessary to fully understand which areas may be submerged during the flood season and which are relatively safe, so as to provide a basis for the overall design and the layout of landscape facilities. According to the hydrological data of each monitoring point measured by the water conservancy department, and the elevation data of the current surveying and mapping topographic map, the flood level inundation range of once in 5 years, once in 10 years, once in 20 years and once in 50 years can be delineated. Although the design elevation has been adjusted compared with the current topography, the overall impact is not large, and the subsequent analysis and layout are based on this basis.
The water flow in the main river channel is relatively fast, which is easy to scour the exposed soil during the flood season, resulting in water and soil loss. © 张骞
Comprehensive analysis of inundation range of flood level - wetland in Caijiahe section © 杭州园林设计院股份有限公司
Comparison between the normal water level and flood level of the wetland in Caijiahe section - the level appears about once in five years, which has submerged most of the river beaches, and only some highlands in the west bank are exposed to the water © 杭州园林设计院股份有限公司
Comprehensive analysis of inundation range of flood level - wetland in Xiaping section © 杭州园林设计院股份有限公司
Comparison between the normal water level and flood level of the wetland in Xiaping section - the level appears about once in five years, which has submerged most of the main river channel area, and the north bank has also been partially submerged © 杭州园林设计院股份有限公司
Delineation of protection levels - avoiding excessive intervention
The wetland can be divided into three levels of protected areas according to the degree of protection and the intensity of human intervention, of which:
The first-class protected area covers the main channel of Huangbai River, and the existing features are completely preserved without intervention, and tourists are not allowed to enter.
The secondary protection zone mainly focuses on dredging the water system and restoring vegetation. Except for some elevated trestle bridges, there are no ground roads and activity venues, and there is less human intervention.
The third-level protected area is located at the outermost periphery and is the main activity area of the wetland park. In this area, natural methods are used to sort out the terrain, create green space, set up garden roads and activity venues, etc., and arrange a small number of service buildings, and the overall development intensity is low.
Facility layout - create a comfortable and safe activity space
Due to the requirements of the water conservancy department, there should be no facilities that affect flood discharge within the project scope. The design is based on the aforementioned rainwater analysis and combined with the flood assessment requirements to determine the construction scope, facilities and elevation control scope. First of all, a continuous elevated plank road system is set up, and the elevation of the surface layer is controlled above the flood level once in 20 years. The upper part is for tourists to walk through, and the lower part does not affect the flood flow. The plank road can travel through the forest, or stand on the wetland water surface, giving visitors a rich experience of sightseeing and viewing. All levels of slow walking trails are set up on the ground, connecting the main tourist areas in series, and forming a three-dimensional cross network with the upper elevated plank road. At the same time, combined with service buildings, bird watching houses, ecological parking lots, hydrophilic platforms and other facilities, the elevation of the first floor of the building is controlled above the 50-year flood level, and most of the main garden roads are above the 10-year flood level. Trails, hydrophilic platforms, etc. are all submersible facilities, which can be properly hydrophilic. The overall design strives to create an ecological wetland park that integrates wetland protection, viewing, popular science, and leisure on the basis of fully respecting the current situation.
The plank road system can travel through the forest and form a three-dimensional cross network. © 王昱
The plank roads shuttles through the forest, which will not be submerged in flood season. © 张骞
The plank roads travels through the forest. © 张骞
The walking trails with low elevation ensures the hydrophilic effect and can be submerged in flood season. © 张骞
The elevation of the surface layer is controlled above the flood level once in 20 years. © 张骞
The grass inlaid slate road in the forest© 张骞
The wetland footbridge © 张骞
Sorting out the water system - communication and interconnection, creating a resilient landscape
The natural base around the main river channel of the base is relatively good, and it has not been damaged by human interference. There are naturally formed shoal sandbars and vegetation, and waterbirds can be seen inhabiting. This is completely preserved and designated as an ecological conservation area. The pits and ponds left by sand excavation outside the main channel are dredged, communicated and connected in series, so that the water systems of the pits and the main river can be connected with each other, and the wetland vegetation is restored to transform it into a series of rain gardens, which can be used in heavy rains. Undertake the surrounding catchment, slow down the discharge to the main river to a certain extent, and also reduce the flow when the upstream floods, and increase the rainwater storage capacity during the flood season. The original pit and pond revetment is relatively steep, and the design changes the shoreline and water depth to a certain extent, so that the water body shape is more natural, and at the same time, it ensures the safe water depth requirements near the shore.
The vegetation in the middle of the shoal sandbars is far away from the tourist activity space, and there are waterbirds nesting. © 张骞
Connecting the pits and ponds left by sand excavation in series, and forming a sponge system after ecological restoration © 王昱
The pits and ponds left by sand excavation turn into a secret environment after repair. © 张骞
The pits and ponds left by sand excavation turn to be wetlands with the greatest potential for biodiversity after repair. © 张骞
The application of current concave land forms a number of small rainwater gardens to undertake the surrounding water catchment. © 张骞
Plant Design - The Power of Native Vegetation
There are a lot of native vegetation in the current situation of the base, among which there are many tall trees with good growth, which are the backbone of maintaining biodiversity and creating landscape. The design requires that the existing trees be preserved as much as possible, especially the trees that reach a certain height and crown width should be 100% preserved. Due to the large scope of the site, the current plant information in the survey drawing is not accurate enough, and the design drawings cannot accurately avoid all native trees. Therefore, in the construction disclosure and construction process, it is particularly important for all parties to communicate on this issue in a timely and effective manner. When there is a conflict between the current arbor and the design of the road, plank road, etc., the design is given priority, so as to finally successfully make all the arbor with a diameter of more than 10cm at breast height. It has been completely preserved. In addition, according to the local climate characteristics and wetland project characteristics in Yichang, a variety of native plants and suitable wetland vegetation have been selected to improve the regional biodiversity.
The retention of native trees forms a tall canopy line. © 张骞
During the dry season, the riverbed is exposed and the meadow vegetation is lush. © 张骞
The plants are wild and full of vitality. © 张骞
The rain gardens are planted with a variety of water and moisture resistant plants, which grow luxuriantly. © 张骞
After the project was launched, it has been included in the third batch of national pilot projects for ecological protection and restoration of mountains, rivers, forests, fields, lakes and grasses, and has successively become a demonstration project of ecological protection and restoration in Yichang City and Hubei Province. After the completion of the project, it has quickly become an important place for Yichang citizens to enjoy leisure outings, fitness entertainment and popular science awareness. You can hear the water gurgling, see fish swimming at the bottom of the pond, children playing in the forest, and egrets flying overhead. It is also the original intention of the design of this project.
There is a height difference between the water systems in the wetland, and the water flow is gurgling. © 张骞
The ecological parking lot © 沛林生态
Project Name：Yichang Huangbai River Wetland Park
Project Location：Yiling District, Yichang City, Hubei Province
Gross Built Area (square meters)：154 ha
Design Company：Hangzhou Landscape Architecture Design Institute Co., Ltd.
Leader Designer & Team：Zhang Qian, Yang Zhongliang, Wang Yu, Wan Changjiang, Ren zishuai, Nie wenbin, Bao Kan yuan, Gao Haifang, Jin Aixue, Huang Hao, Peng Changmin, Mao Jianli
Clients：Hubei Huangbai construction and Development Co., Ltd
Design Completion: June 2019
Project Completion: October 2021
Photo Credits：Zhang Qian, Wang Yu，沛林生态，Hangzhou Landscape Architecture Design Institute Co., Ltd.