The Study Of Huangpu River Riparian Zone Structure And Its Health Assessment

As an important part of the river system, riparian and its structure condition play a major role in achievement of riparian zone function and maintain of river health. The river in highly urbanized areas is influenced by human being activities, its riparian has being changed; as comparison to natural riparian structure, the riparian of urban river showing different cross section structural features and have different effects on the function of riverine. The ecological restoration of urban river and riparian has been the key issues, China’s water conservancy department has also enacted some documents about the health assessment of important river and lakes in our country. Thus the study of urban riparian structure characteristics and health assessment has important reference value to the clarify of the reasons for the degradation of rivers and effective functional recovery.The scope and structure features of the natural riparian zone were systematically reviewed, the general characteristics of the natural riparian zone structure were summarized, based on these, the natural riparian structure partition mode in tidal river network area was proposed with the consideration of tidal river features, which divide the riparian into four parts from the waters to land.Our country and local government have promulgated a series regulations, specifications, plans, guidelines and regulations and so on, which to manage and control the different parts of urban river and shoreline resource, in comparison with the above typical riparian zone features and combine the practical management characteristics and the field investigations, the urban riparian zone was divided into some partitions from the waters to the land areas, including the waterfront intertidal zone, the revetment and buffer zone, and the edge transition zone, which was defined by the waterside control line, the water control lines, flood regulation lines and the terrestrial control line.Huangpu River in Shanghai is selected as the study case to research the current structure features of riparian zone in highly urbanized areas and discuss the delineation of the corresponding channel control lines. The investigation of seven reach of Huangpu River show that:Huangpu River intertidal zone has been seriously degraded, the waterside of dike are hard slope, the achievement of intertidal function only by the residual shoal, currently there are only seven areas which have larger area shoal, for the less manual intervention, most of them are formed under natural factors, in addition to this, there are still floodplain with limited width inside the trestle wharf downstream, the foot of the embankment and a few special terrain(such as tributary estuary).By the restriction of dike types, the revetment and buffer zone of the whole section of the left bank of river estuary and the upstream segment of Huangpu River and more than 50% of other sections have completely disappeared, except Yuan Xie Jing, the revetment and buffer zone mostly appear in two retaining walls and embankments flood prevention wall, there are a certain percentage of revetment and buffer zone in the right bank of He Kou section and Wu Jing section, but most of these district were occupied by factories or agricultural production, a certain percentage of revetment and buffer zone, which also called hidden embankment, appear in Shi Qu section, they have both ecology and social services; the width of the revetment and buffer zone in Yuan Xie Jing and Xie Tang upstream, which emerge in special floodwall types shoreline, is less than three to five meters and the plants in these district are ornamental shrubs and herbaceous, trees and natural vegetation types is relatively few.The area of edge transition zone is equal to the range of land management of riparian, including dikes, flood control road, berms and appropriate riparian plants; most section of Huangpu River have the flood control road with at least six meters width, but most of these aisle is created by use of municipal roads, the passage of Institutions or factory, most of the flood control road in upstream is dedicated channel, riparian buffer zones contain the plants in both the edge transition zone and shore protection area, most of the edge transition zone downstream have few plants, whereas the riparian plants in some districts, as a part of the plants of road and factory, occupy a wider area, but has a low community structure integrity, most of them are trees and grass, parks and the green districts have a large green area, but the native vegetation is less; the edge transition zone in upstream riparian is occupied by agricultural and forest, a certain percentage of riparian edge transition zone of Da Mao Gang and the downstream of The Up Mainstream section is still lack plants, furthermore, the natural plants of riparian is less.The periphery of riparian zone downstream has a high percentage of industrial land, the impervious rate is high, most of these area is maintain by forced drainage, these districts have nothing effects on the keep of ecological function of riparian, agriculture land and forest is the main land type in surrounding area of riparian upstream, the impervious is low, but it still have many sections which the water conservation forest land is occupied by agriculture, the shelterbelt have a fragmentation characteristic and the ecological corridor function of it is damagedThe Wu Jing section of Huangpu River is selected as the study case to have a research on health assessment of riparian, the result show that the study reach is under sub health condition, the main restrictive factors is the low vegetation coverage and the strong artificial interference, these consequence is consistent with the current typical structure of the riparian in Wu Jing reach.