| Accompanied by the rapid industrialization and urbanization in China, the problems concerning urban landscape environment have attracted widespread attention, such as the destruction of the vegetation of the mountain, high strength exploitation of waterfront encroachment on the shoreline and the interruption of waterfront landscape line of sight, visual pollution caused by incongruities in the building volume, color, etc and the surrounding natural environment. With the improvement of people’s livelihood and levels of aesthetic appreciation, people look forward to pursue a living space with elegant and comfortable environment, soft and coordinate landscape. Just like water, soil, air and mineral resources, visual environment of landscape is an Indispensible resource and plays a vital role in urban planning and construction. The assessment of the landscape visual environment is an important part of environmental planning and management. The assessment of urban landscape visual environment lays the foundation for optimizing the spatial layout of the urban landscape, completing control of the height of the building and reasonably allocating landscaping greening configuration. Since mid-1960s in the 20th century, Landscape visual resources have obtained legal protection in Anglo-Saxon countries. Western countries have carried out extensive landscape visual environment (quality, impact) evaluation and most developed countries have established a landscape visual environmental impact assessment system. In China, we have a history of 30 years of EIA practice. The impact of landscape visual environment, however, has never been incorporated into the evaluation of the system (especially for the urban landscape system of visual evaluation theory). What’s worse, at Strategic Environmental Assessment (SEA) level, sustainable development of landscape visual resources has never been explicitly taken into consideration. The appropriate laws, regulations, standards and implementation technical system are still lacking. Therefore, whether it’s for theoretical exploration or reality application, to carry out evaluation of the visual environment of the city landscape will arouse both managers’and public attention. It’s also beneficial to improve the existing environmental impact assessment system.Under the background of "people can see hills, water and other beautiful sceneries of the town", by adopting GIS 3D visualization technique, combined with traditional landscape visual evaluation method, this paper uses both quantitative and qualitative methods. Taking landscape layout and optimization of urban planning as a starting point, centering on the goal of city planning and construction, that is, "the visual quality protection and the landscape aesthetics enhancement", this paper proposes a new set of urban landscape visual evaluation technique processes and norms in planning and assessment, in order to provide reference and basis for the evaluation of similar urban planning. Main contents and conclusions are:(1) The concept of landscape contains two meanings, that is, objective entity and subjective perception; urban landscape is a complex synthesis of the natural landscapes and artificial landscapes. A wealth of beautiful and diverse urban landscape environment allows people to live a comfortable and happy life. Urban landscape visual assessment is to determine the value of the urban landscape environment from the perspective of visual environment, which includes the urban landscape visual impact assessment and landscape visual quality evaluation.(2) The theoretical basis of visual assessment of the urban landscape is urban image theory, urban landscape visual elements of organizational theory, the theoretical analysis and evaluation of the urban landscape and urban landscape overlooking rights theory; Urban landscape visual environmental assessment methodology is the technical system organically combined together by certain methodological principles, including research design methods, data collection methods and data analysis methods. To be concrete, it can be subdivided into four Schools (Expert School, Psychological School, Cognitive School and Empirical School), three methods (detailed narrative method, the public preference method, quantitative synthetic method) and so on. With the rapid development of science and technology,3S technology and 3D visualization tools are also beginning to be applied to the visual landscape assessment in an effort to enrich the landscape visual evaluation methods and means and meaning.(3) Targeting on landscape visual environment in the urban planning of Hong’an County, Hubei province, this paper makes analysis of landscape elements (point-line-surface) in Hong’an county and aims to build an overall understanding of the urban landscape. Hong’an is a city full of communist culture, mountains, rivers and historical myths. The fifteen urban landscape is divided into three categories, that is, natural landscape, historical and cultural landscape, modern cultural landscape, of which there are six first class (excellent) Landscapes, five second class (good) landscapes and four third class (general) landscapes; then landscape control district is conducted on this basis. There are three first class landscape control districts, one second class landscape control district and five general landscape control districts. Sima Hill, Yuntai Mountain, Daoshui River, Jinshahe Reservoir, Hong’an Revolutionary Martyrs Cemetery and streetscape elements together constitute the focus of Hong’an urban landscape, which is also the focus of this visual assessment.(4) By using both GIS technology and the public perception of evaluation, this paper makes qualitative and quantitative evaluation of the visual quality of the landscape and visual impact in Hong’an. The results are as follows:Firstly, the visual assessment of Sima Hill, Yuntai Mountain, etc. shows that at different viewing distances, dotted landscape has a different visual field goal range and impact. Under the 1km-horizon scale, the viewshed of the original surface of Sima Mountain is 2071866.236 square meters, accounting for 65.98% of the total field area; if present residential buildings are counted, the viewshed is 2061214.17 square meters; if residential buildings under planning are counted, the viewshed is 2042944.986 square meters. Obviously, about 18269.184 square meters will be lost. It shows that with the advance of urban planning, the completion of a number of buildings within lkm range brings great damage to the area of Sima Mountain. And the main source of visual interference is cultural centers, theaters, libraries and so on, which are at the northwest of Sima Mountain. Under the 0.5km-horizon scale, the viewshed of the original surface of Sima Mountain is 660624.235 square meters, accounting for 84.15% of the total field area; if present residential buildings are counted, the viewshed is 631820.456 square meters; if residential buildings under planning are counted, the viewshed is 628644.01 square meters. Obviously, about 3176.446 square meters will be lost. It shows that the area that will be lost due to the completion of a number of buildings within 0.5km range is comparatively less. The visual landscape impact of Yuntai Mountain, at two viewing distances, however, is less affected by the implementation of urban planning. It’s suggested that in future urban planning we need to control the line of sight corridor, increase perception of landscape nodes, control of the city skyline and make natural mountain landscape outstanding.Secondly, streets are the main elements of the perceived image of a city and important manifestations of linear landscape. In this paper, Yingbin Avenue is taken as an example. the visual quality assessment method based on the public perception of people indicates that after the planning and construction, the landscape visual quality index of Yingbin Avenue is 72%, and the visual quality of the landscape belongs to grade Ⅱ, that is good; while the original streetscape visual quality index M is 43.8%, and the visual quality of the landscape belongs to grade Ⅲ, that is general. Generally speaking, the implementation of planning of Yingbin Avenue greatly improved the visual quality of the streetscape, but there is further room for improvement. The results based on GIS analysis showed that if visitors come to Hong’an by car, they will lose 21.42 seconds for the perception on Sima Mountain on Yingbin Avenue, mainly from the construction of cultural centers; while in the case of walking, they will lose 142.8 seconds. And in order to ensure an outsider’s perception of Sima Mountain landscape on the whole, we may suggest that the 3-4 storey within 12m of plot B in the south of Sima Hill need to be adjusted.Thirdly, the visual assessment of Daoshui River riverside landscape, which is a linear landscape found that waterfront landscape with better green vegetation cover and higher color contrast has higher visual quality. Human disturbance, such as wire (rod), tower and other power facilities and water bodies’ pollution has a negative impact on the waterfront landscape quality. The visual quality of the riverside landscapes that have already been constructed has been significantly improved and enhanced; the visual quality of those under construction have the lowest scores, the average score of which is lower than the background reference visual landscape quality, showing that the visual landscape quality gets destroyed to some degree during the construction process. The evaluation results based on the public perception found that about 27 percent of riverside landscapes under construction is damaged, while visual aesthetic quality of the riverside landscapes that have already been constructed have increased by 53.5%. The final recommendations focus on the importance of timing differences, the visual convergence and public participation during riverside landscape planning and construction.Lastly, the analysis of visual assessment of Jinshahe Reservoir and martyrs cemetery shows that by using ArcGIS viewshed analysis techniques, set RADIUS2 1km line of sight range for the results of the evaluation, in the case of the original ground surface grid, lake surface area of the visual field is 5.984 square meters; if present residential buildings are counted, the viewshed is 5.641 square meters. And obviously, about 0.343 square meters will be lost. To highlight the visual perception of side effects like water, construction of two landscape view setting Sands Lake corridor is advised. The convergence zone of Jinsha Lake Reservoir spillway channel and Daoshui River is set as ecological security channel, which is not suitable for commercial use and residential construction. It connects the reservoir and Daoshui River and is used for ecological conservation and landscape line of sight protection; the other for viewing sight corridor is important part to perceive Jinsha Lake on Honghua Avenue, where the building height is controled as the viewing corridor of the city core area. Hong’an Martyrs cemetery is an important symbol of the city’s cultural landscape. With the construction of Apricot Avenue, southeast of the martyrs cemetery will be a broad visual channel. Based on the results of line of sight of the park, it’s recommended that the height limit control of residential housing at the southeast of the side door of Martyrs cemetery is 13.45m, and five storeys are the extreme height. The analysis of DEF viewpoint indicates that the height control of residential housing is mainly for M plots. According to the minimum principle, the height is restricted within 11.2m, and four storeys are the extreme height.(5) Urban landscape visual assessment is an important basis for decision on urban planning and construction, and rationalization of the visual aspects of the layout. In the first place, relevant laws and regulations need to be improved. The importance of protecting the urban landscape visual resources needs to be announced. Legislation needs to be implemented to ensure that the line of sight corridor. What’s more, it provides legal protection for the urban landscape planning and management. Secondly, the urban landscape visual assessment can be introduced to environmental impact assessment system and urban planning and approval in order to reduce the maximum possible adverse landscape impact of construction projects; On the one hand, during siting stage or land transfer phase, the planning department in addition to the audit of the construction project of the total plane, has to take into consideration the importance of the project in accordance with the surrounding landscape environment, have a choice to carry out the landscape and visual impact assessment. The evaluation results are very crucial references for the land transfer. On the other hand in the construction phase of the audit, in addition to review whether the program are in compliance with planning conditions, the planning and management department should also carry out landscape and visual impact assessment from experts and the public, based on the evaluation results, the feasibility of the construction project plan is decided and measures to mitigate the negative impact will be proposed. Again, much attention needs to be paid to public participation in visual evaluation of the urban landscape; it is necessary to expand the breadth and depth of public participation in the planning because this is the weak link. Through the public agreement on landscape, a more humane control and management of landscape resources will be achieved so as to promote changes from landscape control to landscape governance.Significance of the paper is:① initially constructed an urban landscape visual evaluation system based on point-line-surface combined urban landscape elements. From the classification and grading of urban landscape, the determination of the scope of the evaluation, the identification of visual environmental impact, the screening of assessment factors, the selection of evaluation methods and technologies, the prediction and evaluation of visual environmental impact, the mitigation of impacts and feedback and Implications for urban planning, etc. This paper aims at exploring how to build a visual environmental assessment system featured by complex landscape. ② build a methodology based on GIS technology and the public perception of the urban landscape visual assessment combined with the evaluation. From the visual quality assessment and visual impact assessment of urban landscape, by using three-dimensional analysis, viewshed analysis, line of sight analysis, which all belong to GIS technology, this paper makes analysis of the landscape visual evaluation during urban planning of Hong’an County, Hubei Province, providing a reference for other landscape visual impact assessment of urban planning process.Limited by time, the theory and methodology of the urban landscape visual assessment of this paper is still preliminary, and there is a need for more research in the latter, mainly in: ① Due to the diversity and complexity of urban landscape systems and the spatial organization of the landscape, making a complete, systematic and scientific theoretical system of the urban landscape visual assessment requires constant deep study and exploration; ② with a landscape and visual impact assessment of the three-dimensional urban planning decision support system or geographic information systems, the need in the late application and practice to develop, in order to provide a unified, intuitive, visual landscape full system simulation platform for urban planning and management; ③ visual evaluation of how the urban landscape into urban planning and management, and on the basis of existing land use approval and the approval of the building, there may be visual impact of construction projects on important regional landscape, into consideration institutional landscape, the need to explore further in practice. |
PDF Full Text Request