Study On Riparian Ecosystem Degradation Assessment Of Urban River In Shanghai

River degradation becoming the primary problem faced by the river ecosystem of countries all over the word. With the accelerating process of urbanization, riparian zone, especially urban riparian ecosystem suffers serious degradation because of human interference. Degradation assessment is not noly the important means of protect and repair the riparian zone ecosystem, but also is the effective proof of river regulation and sustainable management. Based on this background, try to study on riparian ecosystem degradation assessment of urban river is useful abstractly and practically for urban riparian zone for planning and management regulation.Literatures and references are complete studied, research progress and degradation mechanism of riparian zone at home and abroad are described. Based on which, connotation of urban riparian zone is showed. Practices on assessing riparian zone in Australia, United States, British, Sweden, South Africa and China are concluded from river health assessment, status assessment and ecological restoration and reconstruction after-assessment three aspects, and evaluation factor database is established.Based on horizontal structure of riparian zone, the paper try to characterization of riparian ecosystem degradation degree from waterfront zone, revetment zone, buffer zone and nearshore zone four aspects. With consideration of the characteristics of urban riparian zone in Shanghai, a degradation assessment system of riparian ecosystem of urban river is established with 4 first-grade indexes (including waterfront zone, revetment zone, buffer zone and nearshore zone) and 23 second-grade indexes after determining the assessment indicators, assessment principle, assessment standards and assessment model.Suzhou Creek in Shanghai is selected as the study case for practice, whose natural characteristics are under significant destruction and degradation due to rapid urbanization.43 reaches were selected as the assessment units on the main stream of Suzhou Creek, constructs indicators database using the method of remote sensing image interpretation and spot investigation, measures the Riparian Comprehensive Situation Index (RCSI). Then it identifies the level of degradation interprets and the RCSI response to reaches location, land use types and two banks on the basis of ANOVA analysis and Spearman correlation analysis, and put forward remediation planning and restoration strategies. Meanwhile, the paper preliminary discussed the scope of riparian zone of Suzhou Creek, and the environmental effects of riparian land-use change of urban river are studied on the basis of Pearson correlation analysis.The results show that:(â…°) The riparian comprehensive situation of Suzhou Creek is in the poor grade with RCSI distributing from 3.79 to 25.03, and no reach is in the minimal degradation, and 69.8% reaches belongs to serious and extreme degradation grade; (â…±) River channelization and revetment hardening of Suzhou Creek result in more than 85% reaches of the waterfront and revetment zone status belonging to serious and extreme degradation grade, the width of waterfront zone and type of revetment are the key factors to the grade. Though 72.1% reaches of the buffer zone status belongs to slight and moderate degradation grade, irrational vegetation structure and single species problems are still remained. Rapid urbanization makes more than 50% reaches of the nearshore zone status belonging to serious and extreme degradation grade, and impervious area ratio and facilities richness degree are the crucial factors to the grade; (â…²) The results of analysis of variance (ANOVA) reveal that human activity intensity and urbanization are the key forces to cause RCSI and most of other indexes having significant differences in reach location, land use types and two banks, while waterfront zone width, revetment slope, erosion degree, a diversity index and longitudinal connectivity have no significant differences; (â…³) It has most significant correlation among RCSI, first-grade indexes and second-grade indexes. (â…´) The scope of riparian zone based on function of control point source pollution and provides biological corridor range of 5.19-30.00m. The scope of riparian zone based on function of the shipping dock or industrial land range of 0.00-7.00m, The scope of riparian zone based on function of open and public housing range of 6.00-30.00m; (â…µ) 100m buffer landscape corridor is better reflects the environmental effects of riparian land-use change of urban river.