Governance of urban river eco-design methods

Summary on how to restore urban river ecosystem, from the design point of view of ecological river management requirements and recommendations proposed by many, to abandon the traditional design methods, ecological design were outlined.

Keywords: urban river; ecological governance; Design

In the past, often biased towards urban river water for irrigation, flood drainage, bank protection sclerosis, a serious drainage phenomenon, with both sides living sewage and garbage into, resulting in many river into a drainage ditch, can not survive in aquatic ecosystems has been greatly damaged. In the increasingly serious environmental crisis, the city's builders started looking for an effective ecological solutions to solve concrete jungle isolated human and natural phenomena, creating a clear-shore green, insect called frogs, man and nature, waterfront living environment [1].

Ecological restoration is a systematic project, the ecological river management measures should be multifaceted, comprehensive, and these measures focus on the core is how to restore the ecological system, which made for a new challenge to designers [2]. Each design element should create favorable conditions for ecological restoration, creating ecological river, which materialized through the manual, so that treatment can be close to nature after the original ecology of rivers, reflecting the harmony between man and nature, and gradually form a lush vegetation, biodiversity, Natural Wild, water quality, populations of species interdependence, and to achieve a self-purification, self-repair capacity of the water conservancy project. [3] Therefore, designers should make more use of natural anti-jamming, self-repair capacity to handle the relationship between man and nature rather than the form of a large number of artificial structures and to replace the natural, ecological design and this is the difference between traditional design methods.

1 channel linear design
Overall linear design of the river channel graphic design. As scarce urban land, river waterfront continued to be occupied, less and less water, river width, the narrower the more repair, but to flood the need to ensure that cross section, had the river straightened, deepened the river bed, so that the strength of the barge Hom asked to gradually increase, gradual increase in construction costs, and the decline of ecosystem function, river discharge into the basic channel, which is contrary to the sustainable Development strategy. And Ecology governance also need to return to the river restored waterfront area, the demolition of the original visually monotonous, stiff, heat island effect was channel bank protection, river restoration as a natural form, should turn the corner, width combination of a straight line to avoid the line.

Natural meandering of the river and riparian areas for a variety of biological and create a suitable habitat, the landscape is the basis of diversity of life. Bend, at the concave bank can provide breeding sites for biological and peak comes, can have as a refuge places, the proliferation of biological life increase wetlands, bend, shallows, deep pools, sandbars and other forms of artificial semi-naturalized, not only add natural beauty, but also can take advantage of the diversity of river morphology to improve habitat diversity, thereby improve the diversity of biological communities. with respect to a straight line of the channel design is more natural meandering river can increase oxygen content in water, increase aeration, and therefore more conducive to improving the living environment of organisms.

From an Engineering point of view, the natural twists and turns of the river to alleviate the flood line, reduction of energy flow, control flow, it also reduces water erosion on the downstream embankment, along the embankment of the protective effect. Back to still river, waterfront recovery, making the city building designers to design in the river section of the left choice, without the use of high-strength structure protection on the riverside buildings. conform to the river regime, due to river system should be no doubt in the Engineering aspects of economic is more favorable.

2 channel section design
The choice of river sections in addition to considering the dominant function of rivers, land use, should also be combined with riparian landscape, reflecting the hydrophilic, water and land as far as to create conditions for the continuity of the ecosystem.

Both the traditional rectangular river water to meet the requirements of the dry season, but also to meet the requirements of flood discharge, often in the form of high-split Hom, thus leading to water ecosystems and terrestrial ecosystems isolation, amphibians can not leap high split Hom, the propagation of biological communities separated by man-made. trapezoidal cross-section of the river in the section of the form to solve the continuity of land and water ecosystems, but less hydrophilic, steep section of the biological growth is still some obstacles, but not conducive to landscape layout, while the ramp section and subject to restrictions on construction sites. compound cross section below the water table in the regular part can be rectangular or trapezoidal cross section, above the water level in the regular part of bank protection can be set to ramp or two, a small flow in the dry season when the return flow main channel, flood flow, allowing flood floodplain, cross section suddenly becomes larger, so the compound channel will resolve when the hydrophilic constant level requirements but also meets the requirements of flood when the flood level, the landscape for the Waterfront design space, but split due to the reduction of the revetment ridge height, structural resistance decreases, rock revetment structure without the use of mortar, concrete and other rigid structure, can take the form of low-intensity flexible revetment. less area of ​​human activity , to meet function under the premise channel, should reduce the traces of human governance, try to keep the face of natural rivers, so that the original ecosystem is not destroyed. So the choice in the river section, as far as possible to maintain the natural river section, while maintaining difficulty of natural river section, press the compound section, trapezoidal cross section, rectangular cross-section of the order of selection.

However, in the course of river, but also one of the sections should be avoided. A different cross section can produce changes in water flow rate, increased aeration, thus increasing the oxygen content in water. Diverse river section in favor the diverse ecological landscape, then a diversity of biological communities. For example, in shallow habitats, excellent light and heat conditions, suitable for the formation of wetlands for birds, amphibians and insects inhabit. depression in the water, fish and molluscs rich, they are carnivorous food source for migratory birds, bird droppings and fish and contribute to the fatness of the growth of aquatic plants, aquatic plants and plant food is the food of birds, thus forming a favorable growth of birds food chain. pit habitats, as water temperature, solar radiation, food and oxygen content change with depth, so easy to form a stratification of aquatic communities.

River bank protection in the form 3
The traditional aspects of river bank protection most of the material and the mortar stone with concrete and other hard materials, the whole embankment to form a closed system, like a river to put a layer of armor, but only to consider the safety of the river, but they ignore environment and ecology of river systems and other plants and animals and microorganisms living environment; not only hinder the circulation of water eco-system, even the animals and plants, microbes have been blocking the whole food chain; groundwater and river water can not be timely communication, the water cycle process is cut off, the river turned into not only into the closed water bodies, which goes against the city's ecological construction.

In the process of building an ecological river, river bank protection meets the requirements of ecological, growth and reproduction of plants and animals are able to provide a place, whether self-repair capabilities, the designer should focus on things to consider. Riverbank protection should be through the use of plants or plant and the combination of geotextile material, with a certain degree of structural strength, can reduce the slope and the foot of the slope instability and erosion, while the symbiosis can be achieved with a variety of biological reproduction, self-healing capacity, with purification function, can breathe freely hydraulic structure.

At present, many designers made a number of effective bank protection design methods, such as geogrid slope reinforcement technology, stem puzzle slope protection, slope reinforcement using the technology of plant roots, water seepage concrete technology, stone cage, eco bags, eco-block [4]. These structures are common: one has a large porosity, can grow plants on the embankment, to provide habitat for biological, and can make use of plants to increase the role of the structural stability of the embankment; Second, groundwater free to communicate with the river, to achieve physical, nutrient and energy exchanges and promote the cycle of water vapor; third is low cost, no long-term maintenance and management, with self-repair capabilities; Fourth flexible revetment materials to meet the twists and turns bank line. But there are some limitations of riverbank protection, choice of materials and construction methods, the protective ability of banks very different, so depending on the slope in the form and choose a different structure. gentler slope of the river , you can choose eco-block, geogrid and other flexible structure, steep slope of the river, you can choose rock blocks, stone cage, seepage of concrete and other semi-flexible structure; ecological embankment construction is generally low early strength the need for conservation of a certain time in order to plant growth, otherwise it will affect the future play a protective role; construction season has some restrictions, often limited to plant dormant season.

As the saying goes, "shrimp shrimp Drive, crab with crab Road", all kinds of creatures have their own unique living habits, and different ecological revetment structure to meet the needs of different biological growth and reproduction, such as type of stone revetment can provide snail, crab dwelling organisms such as cling, natural geogrid embankment slope and loach and other molluscs can provide growth, shallow lots suitable for the propagation of plankton, fish pond area suitable for events, so in the revetment form, according to the topography, the original greening of vegetation, choose a variety of bank protection in the form, for a variety of biological creation of an appropriate growth environment, the design reflects the idea of ​​diversity of life, both to maintain a variety of banks in the form, extending the original occasion of the edge effect of water, and gave the provides a biological growth environment, migration corridors, easy to form a complete biological communities. reposted elsewhere in the Research Papers Download http://www.hi138.com 4 Plant Design
Plant roots can hold the soil, improve soil water holding capacity, increased soil organic matter content, both to improve the structure and properties of the soil, increase erosion resistance and anti-erosion ability, to play the role of solid earth embankment, but also improve riparian soil fertility, improve ecological environment. and over time, plants continue to grow, these effects will be continuously strengthened.

Plant leaves may retain rain water, filtering surface runoff, aquatic plants and leaves to offset the wave energy, thus helping protect the embankment, water purification, water conservation role. Rich plant communities, but also for animals to provide spawning grounds of aquatic and habitat [5].

Plant also has a role in water purification, sewage and other substances in the nitrogen and phosphorus absorbed by plants, can be transformed into the nutrients needed for growth, turning waste into wealth, so that "dirty" "water" separation, reducing the level of river eutrophication . Researchers ecological monitoring of governance found in the river, NH4 +, TP, CODMn and SD indicators are significantly reduced, water quality has been significantly improved [6].

According to the different growing conditions, plants are divided into regular channels of aquatic plants below the water table, river slope plants, plants, and flood embankments above the flood level of plants. When selecting plants, not only to achieve a variety of landscape effects, layering clear , gives a visual feast for the eyes, but also has a good ecological effects, and functions under different water level, choose the appropriate water level in the growth of the plants, and certain features. in constant water level and water flow below the flat place, should be Ecological cultivation of aquatic plants and more beautiful, and its main function is to purify water, provide habitat for the aquatic animals and food venues, landscaping water, according to select the appropriate channel characteristics of submerged plants, floating plants, emergent plants, according to their ecological habits Science configured, the implementation of mixed cropping and block planting combination; constant water level to flood the area is the focus of river soil and water conservation, and its function on the bank stabilization plant, soil conservation and beautification of the role of banks, the river slope part of the wet plant-based, short-term flood part of the selection capability of plants flooded, river plant communities of the configuration should be considered, niche complementarity between species should be up and down a level, so connected, the root depth of the phase scattered to perennial herbs and shrubs subject, without affecting the flood drainage under the premise of a small amount of tree species for planting. These are the rivers flood and water conservation plant green highlights, is the main section of the river landscape construction, community construction should be chosen to be the natural formation of the local film Forest dominated the landscape of trees, species should be colorful and diverse, the proportion of evergreen plants can be increased to compensate for flood recession in the winter landscape plant the following defects. In this way, aquatic plants and trees filling the river with echo, formed at different levels of plant landscape.

In the choice of plant species, we should try to select the appropriate climate and environment of the species in the region, without causing invasive species, plant growth landscape formed after the layer should be clear. The water resistance of the occasion to choose a good edge, extensive management, plant developed root system, soil reinforcement and strong plants, such as vetiver grass, Bahia grass. artificially contaminated river or a more serious non-suburban section of the river of sewage pipe network, to select the environmental effect, can effectively eliminate the nitrogen and phosphorus, oil, toxic chemicals plant species, in order to achieve the purpose of the river ecosystem, such as Elodea, Vallisneria, Myriophyllum, Ceratophyllum, Lemna minor, canna, etc.. The study showed that the ratio of floating submerged plants, emergent plants to remove contaminants more effectively. There planted tank or wetlands where aquatic plants can adapt to the situation in depth, configure a variety of aquatic plants, reconstruction of aquatic plants, fish, birds, amphibians, insects and animal species good habitat, such as reed, lotus and so on.

In summary, the design of ecological river needs the cooperation of various factors, designers need to expand the idea of ​​combining ecology, Engineering, water conservancy, knowledge, complement each other, to form an effective design.

Ecological river management is a sustainable Development of systems Engineering, through design, construction, maintenance and a series of measures to simulate a biological growth of the appropriate environment for all types of aquatic, terrestrial and amphibious animals, plants, and provide habitat for microorganisms , breed, and place of refuge and, in addition to the Engineering and vegetation measures, must also have a choice of stocking of aquatic animals and bacteria, and restoration of biological diversity, ecosystem reconstruction of biological systems.

5 References
[1] leaf pieces high, Shuai, Zhang Jinjuan. River Plant Biodiversity Research Measures Progress and Prospects [J]. Water Resources and Architectural Engineering, 2008,6 (2) :41-43.

[2] Han Yuling, Yan Qibin, should be intelligent, and so on. The application of plant measures to build an ecological understanding of the river and thinking [J]. China Water Resources, 2006 (20) :9-12.

[3], Wang Jianxin, Qiu Junjie Sun crossed, and so on. River Ecological Restoration Project on the water of total nitrogen, total phosphorus and other indicators of [J]. Zhejiang Water Conservancy and Hydropower College, 2008,20 (1): 53 - 55.

[4] Zhu Yongxiang, Peng Yueqin. Taiyuan ecological river bank protection of [J]. Information Development & Economy, 2007,17 (5) :279-280.

[5] Xin-Jun Wang, Luo Jirun. Urban river in the comprehensive treatment of ecological revetment construction [J]. Fudan University (Natural Science), 2006,45 (1) :120-126.

[6] Li Xinzhi, Wang Xiaode. On vertical urban river bank protection in the transformation model [J]. Water Resources Planning and Design, 2009 (6) :60-63.

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