Effect Assessment Of Urban River Ecological Restoration

As the "Construction of New-type urbanization" was officially put forward in the 18th CPC National Congress Report, a great change has taken place in the Chinese urban planning and construction from people’s concept. "Ecological livable city" has been a key word in this great revolution gradually. As a component of natural landscape, a part of precious resources for humankind, a dimension of riparian space, rivers have been playing a significant role in maintaining ecosystem working well, furthering long-term prosperity and stability of human beings as well as enhancing urban competitiveness. Due to its ecological and social natures, the unique properties have created and brought about natural beauty and economic fortune. However, in the past, people usually tended to pursue economic benefits at the cost of environment; unfortunately, rivers had become one of victims in the process of urban development. With the advancement of people’s consciousness in recent years, river ecosystem, urban river pollution and riparian landscape have been restored and repaired. Comparing to traditional engineering-oriented river modification, "ecological restoration" has been mainstream to guide river regulation work in this new time. "How to keep the balance between urban river ecological protection and water resources development and utilization", "how to create harmonious water environment between human and nature" and "how to meet the common needs of all humanity by using ecological restoration", based on these issues, this paper attempt to provide a reference answer though an effect assessment of urban river ecological restoration.From the prospect of urban river eco-restoration, a set of effect assessment system being applied into general urban river eco-restoration has been presented and practiced in this study, which has covered river ecological functions, restoration measures and production benefits of river. Discussions involved in influencing factors of eco-restoration measures and river ecosystem services.First, reviewing the international experience on the practice of urban river restoration techniques and the subsequent effect assessment, this thesis established an effect assessment system named as "environmental effect-value benefits" and calculating methods for each index according to the functional classification of urban rivers and eco-restoration technology implementation system. Environmental effect system includes indicators which are often used in the river health evaluation, such as ecological, hydrological and geomorphologic indices, also includes some indicators reflecting eco-restoration influences. Social economic function of urban river belongs to value benefits system, such as landscape, recreation, etc. Use a combination of both can be more accurately reflect the effect of urban river restoration.Second, as the mother river of Beijing, Yongding River was a case study to prove the assessment method. River eco-restoration measures were summarized on the basis of field work and "the Yongding river green corridor planning" which carried out along the river. Such measures covered ecological revetment, dike repair, reclaimed water supplement, water system reconstruction, as well as wetlands, ecological islands, repulse bay and streams restoration. By means of data collection, field work and questionnaires, an effect assessment of eco-restoration of Yongding River was carried out under the foundation of "environmental effect-value benefits" evaluating system. The case study used the method of factor analysis and composite weight with objectiveness and practicability. The results show that the restoration of Yongding River was successful from the overall. Yongding River which was ecological degradation and sand filled reappeared rippling, sparkling scene again though this restoration project. Meanwhile, the contradiction between flood control and greening was solved, but water quality in the urban area cannot achieve the design standard. As a result, water purification and maintaining efforts should be improved according to the assessment.Third, this study focuses on the changes of Yongding River ecosystem service functions after restoration form 4 aspects of provisioning, regulating, culture and support. Cluster analysis was applied to classify different functional zones, then calculating ecosystem services scores of these different functional zones. It was concluded that there was a difference between different types of river sections, but not significantly. To some extent, ecological restoration project ensures the healthy functioning of the river.Finally, a summary of the paper contents is given and the assessment system and quantitative method proposed is simple and easy to practice. Some further suggestions and the tendency of urban river restoration in the future were put forward in the end so that the effect of urban river regulation could be assessed scenically, the construction and development of civilized and ecological city could be promoted and the common goal of harmonious environment-friendly society between human and nature could be achieved as soon as possible.