Study On The Effect And Its Influencing Factor Of Urban River Restoration In Shanghai

Rivers are the natural resources in urban areas. In urban area of Shanghai and as a great component in urban water bodies, rivers have been playing an important role in maintaining the urban ecosystem as well as transporting and serving functions within urban economic development and social lives. Due to the integrated influences of industrialization and urbanization, urban rivers have seriously damaged and interfered by human activities. Thus, river restorations and aquatic improvements have become one of the key issues in environmental protection for the metropolis of Shanghai. Based upon the background of river restoration in Shanghai, there was relatively lack of assessing the environmental factors systematically during the process of river or watercourse restoration. Furthermore, it is also believed that the understanding of the restrictive factors were insufficient, which directly make adverse impacts to the effects of restoration. Consequently, attempt to establish the effect and its influence factors assessment in the process of river restoration is of great theoretical and practical significance.On the purpose of understanding the tendency that being developed in urban river restoration, a review of the urban river restorations has been carried out in this thesis. The review emphasized on the benefits or experience of the United States, Britain, European Union, Japan and Australia, including the "Public Comfort Assessment" and "Management of Drainage Area" in the US, "ICPR Group" and "Water Framework Directive" in the EU, "Multi-requirements of River Restoration" in Japan, "River Health Assessment" in Australia; concluded the pressing problems that being confronted during domestic river restorations, such as heavy polluted of water bodies, the ratio of water areas decreased, singleness of the river function, etc.According to the review, the thesis intended to discuss the theories and methods being applied into the effect assessment of urban river restoration in Shanghai. Discussions involved in guidelines, theories, methods, system of environmental target and follow-up assessment. Among these aspects, the key points are inclined to establishing the system of environmental target for the effect assessment as well as the follow-up assessment aim to the influencing factors. Under the foundation of representation, synthesis, prediction and maneuverability, the thesis borrowed some ideas from the "multi-target overall assessment" and "Analytical hierarchy process (AHP)", the target was designed as four "Components" with two "Hierarchies". Several measures like field sampling, lab analyzing, modeling, etc. were considered in the follow-up assessment so that the influencing factor assessment could be developed from the qualitative level to the quantitative level. As a result, the countermeasures for improving the urban river restoration would be provided according to the assessment.Based upon the project of Shanghai Water Authority, Restoration and Remediation of Small Malodorous Black River in Urban Area of Shanghai (No.:Hushuike2004-05), the thesisinvestigated a great number of feasibility reports as well as the status reports of the river restoration projects in Shanghai. The results of the background investigation indicated that the focus of status investigation should continuously be strengthened and there is a close relationship between the technologies and the restoration effects. After comparison and analysis, 18 rivers in the urban area of Shanghai were selected as the model of the effect assessment. The effect assessment of the urban river restoration in Shanghai confirmed that "Hydrodynamics condition", "River system connectedness", "Cost of the restoration technologies", "Subsequent measures for maintaining the river restoration effects", etc. were the major influencing factors of river restoration. As to the follow-up assessment, the thesis attempted to assess the influencing factors respectively. The sequence of the follow-up assessment was followed by the assessment strategies, analysis of the causes and measures of counteract the limiting factors. To some extent, the effect assessment pointed out the direction of improving the effects of river restoration in Shanghai.The case study of the follow-up assessment acted on the hydrodynamics condition was mainly used the methods of field sampling and analytical data. One of the model rivers that belong to the scope of the rivers being assessed previously, named Mudu Creek was involved in the follow-up assessment. The Suzhou River, which is a main watercourse in Shanghai and with relatively good condition in hydrodynamics, was also assessed to make a comparison with the Mudu Creek. The experiment suggested four dimensions of hydrodynamic impacts (impact of river system connectedness, impact of natural flood and ebb, impact of seasonal conversion, impact of astronomic tides), and the results indicated that: (1) The rough regulation of four dimensions is that impact of river system connectedness > impact of natural flood and ebb> impact of seasonal conversion > impact of astronomic tides, and water system connectedness could be thought as the closest relationship with hydrodynamics. (2) The influencing factor of hydrodynamics aggravated the malodorous and black conditions of the urban rivers and with direct adverse impacts to the river restoration effects. (3) The influencing factors of hydrodynamics to the urban river restoration in Shanghai demonstrated the importance and urgency of the study on the effect and its influencing factors. The thesis emphasized that hydrodynamics condition should be continually improved within the whole processes of urban river restoration.