Research On Investigation And Greening Reform Of Roof Space Of Xi'an Ming City Under The Guidance Of Rainfall Utilization

Since the reform and opening up,China's rapid urbanization has made remarkable achievements.The process of urbanization has destroyed the original natural hydrological process,triggered urban waterlogging disasters,and the imbalance of rain and flood management has gradually endangered people's production and life and property safety of various public utilities.In 2014,the requirement of sponge city construction was put forward,which made the whole society pay more attention to the importance of comprehensive management of water environment.As a means of "ecological compensation",roof greening can better alleviate the contradiction between the shortage of urban construction land and the lack of urban green space at present.It is an important technical measure for cities,especially the old urban areas,to cope with the harsh human settlements and improve the contradiction between human and land.The Mingcheng District of Xi'an is a typical old city and historic block in Xi'an.It has been facing difficulties in sponge transformation and space constraints in rainwater and flood problems.It is a common phenomenon that the roofs of buildings occupy about 30%of the urban area are largely idle.How to use the roof space resources in the old urban areas as the countermeasure and grasp of the rainwater problem is extremely necessary to solve In this study,from the perspective of landscape architecture,starting from the investigation of urban roof space and the adaptability of roof greening,the role and influence of roof greening as a part of urban ecology in rainwater management and its transformation are discussedThis paper takes the roof space of old urban Mingcheng District and its rainwater and flood benefits as the research object,and explores three problems by using the methods of GIS digitalization,classification induction and field investigation:(1)how many roof spaces can be built in Mingcheng District;(2)what greening modes can be corresponded to by roof space;(3)what rainwater and flood benefits can be brought by these greening modes and how to respond to them.Use the strategy of transformationIn this paper,four parts are discussed.The first part is the basic research,summarizing and discussing the current research situation,combining with the research content to determine the technical route and research methods.The second part is the investigation and research.ArcGIS is used as an auxiliary tool to interpret the high-definition remote sensing image map of Xi'an Ming City.According to the different attributes of the building roof,the attribute database is established,and the proportion of different attributes of the roof is counted.The third part is classified research and benefit deduction.According to the construction conditions of roof greening,building roofs are classified,three types of building roofs in Mingcheng District are summarized and screened,corresponding greening transformation modes are selected,and the hydrological benefits of different proportion and types of roof greening are deduced.The fourth part provides strategies and related technologies for different types of roof greening transformation modes.Technical design guidance,from the design structure,plant selection and rainwater utilization aspects of recommendationsIn this study,the old historic blocks which are seldom studied are selected,and the particularity of the site is fully taken into account,so as to lay a foundation for the rational planning of regional roof greening.(1)In spatial data survey,the use of GIS technology to investigate the roof of buildings in Mingcheng District is the first time to use manual extraction and quantitative methods to study the roof and roof greening in Mingcheng District.(2)Classified and screened the building roof space with green roof in Mingcheng District,summed up three forms of roof with green roof:flat roof,sloping roof and sloping roof,and three modes of greening transformation:light roof greening,sloping roof greening and roof garden.(3)Rainfall and flood benefits of roof greening in Mingcheng District are analyzed and deduced,and specific strategies and practices of rainwater utilization are put forward.