| Natural sponge is an important rainwater storage space.In the process of rapid urbanization,due to the unreasonable exploitation,the natural sponge was severely damaged,the rainwater storage capacity is greatly affected,leading to water security problems of water resources,water environment and flood disasters,such as city outstanding.It is necessary to reconstruct the damaged urban space to solve the problem of urban water security and make the use of urban space in accordance with the laws of water.The reconstruction of urban space needs to understand the destruction of the natural sponge and analysis the intrinsic mechanism between the natural sponge and the regulation ability of the city.And then puts forward the urban space reconstruction strategy under the guidance of the theory of the sponge city.Firstly,this work explains the connotation of the basic theory of sponge city,and puts forward the key points of constructing city.According to the characteristics of sponge mountain city,and puts forward the key technology of sponge city construction in Liangjiang New Area.Secondly,from construction land,water ecosystem and impervious surface analysising the destruction of the natural sponge body,and the comparative analysis the destructive natural sponge effect on the city storage capacity.And then put forward the reconstruction of city water system in a regional scale,in a watershed space reconstruction city impervious surface management and follow the terrain's city space reconstruction strategy,and puts forward the measures,suggestions of sponge city construction.The main research contents and conclusions of this study are as follows:The first chapter describes the background and significance of the study,defines the concept of the sponge city and space reconstruction,the research progress in China and abroad,research content,ideas and methods.In the second chapter,the author introduces the general situation of the study area from the aspects of nature,social economy and land use,then using the DEM terrain data to extract the water system,at the same time,the watershed unit is divided into three parts.The third chapter,analysing the connotation of the basic theory of sponge City,and puts forward the key points of constructing city according to the characteristics of sponge mountain city,and then put forward the key technology of sponge city construction about Liangjiang New Area.The fourth chapter,the author studies the destruction of natural sponge body in the process of urbanization from the following three aspects: the change of water ecosystem,the gradient of construction land and the change of water surface.First of all,from the expansion of land use space,the expansion rate of construction land and the expansion of the intensity of the terrain,we analyze the characteristics of the spatial and temporal changes of the land use.The study showed that from 2000 to 2014 Liangjiang New construction land gradually extended to the high terrain.Secondly,analysing the change of water ecosystem from the three aspects of land use of river buffer,river system and the damage of river network buffer zone,lost of lake and reservoir pond.The study found that,from 2000 to 2014,The proportion of construction land in the land use structure of the buffer zone of river network is improved significantly,and other ecological land types decreased,the farther away from the river changes greater,water density,ratio of water,river development coefficient and the connection rate are all decreased,the main part of change is located in the southwest of the rapid expansion area,large ponds disappear rapidly.Finally,the mixed pixel linear separation technique is used to extract the impervious surface,and the temporal and spatial variations of the impervious surface are analyzed.The study showed that from 2000 to 2014,two rivers area of impervious surface expansion,impervious surface area increased 259.74 km2,and the impervious surface extension and water ecosystem destruction showed a spatial coupling,disappeared rivers and straightening rivers are mainly located in the new impervious surface area.The fifth chapter,the influence of the sponge on the capacity of the city is analyzed from the aspects of infiltration capacity,runoff production capacity,surface run off resistance capacity and accumulation capacity.First of all,using the SCS-CN model to analysis infiltration capacity change and surface runoff generation capacity changes,research shows that from 2000 to 2014,two rivers infiltration capacity weakened,but the infiltration capacity of the spatial differentiation is obvious,with the increasing return period,regional mean runoff depth increased,spatial differentiation increased.Secondly,the minimum cumulative resistance model is used to analyze the change of surface runoff resistance.The study showed that changes in surface runoff resistance ability showed a spatial differentiation,the Western moon mountain forest conditions become worse in 2014 than that in 2000,resulting in the runoff convergence resistance decreases,while the southwestern city for extended landfill river resulting from the river "source" distance increases,increase the runoff convergence resistance;finally,the qualitative analysis of city construction change the terrain lead to surface runoff accumulation ability change.The sixth chapter,from the runoff system reconstruction,lakes and reservoirs,ponds and wetland system reconstruction,city water system reconstruction of riparian ecosystem three aspects reconstruction of urban water network system at regional scale.According to the effect of hydrological environment,the impervious surface control measures are put forward,such as green roof,permeable pavement,and so on.The use of sunken green space,rainwater garden measures for space reconstruction,and put forward the system integration measures of different scales,and the combination of city drainage unit,city incentives and other suggestions for city construction countermeasures and measures.The seventh chapter is the summary and Prospect of the research results. |
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