| Affected by the global extreme climate change,meteorological disasters occur frequently,suddenly and widely,the frequency and intensity of disaster events around the world increase and enhance.In recent years,local short-duration rainstorm frequently occurs in large and medium-sized cities in China,which seriously affects urban safety and restricts urban economic development and social harmony and stability.Urban waterlogging has become a practical obstacle and a difficult problem of ecological security governance that hinders the normal operation and healthy progress of cities.In the meantime,the rapid urban expansion promotes the dynamic change of urban land patches,and the urban landscape pattern evolves in time and space.Urban landscape pattern affects the frequency and intensity of urban waterlogging by slowing down the production and concentration process of surface runoff.Using the stormwater regulation and storage measures to combine urban landscape pattern planning with urban waterlogging prevention can effectively alleviate the surface runoff generated by short-term rainstorm,relieve the pressure of drainage pipe network,reduce the frequency and intensity of urban waterlogging,promote the construction of urban ecological security pattern and achieve sustainable development.This paper selects the main urban area of Xi’an as the research area.The spatial distribution map of landscape pattern in the main urban area of Xi’an City based on the remote sensing data sets from 2000 to 2019 was extracted,and validated with actual land use data.The methods of SCS model,landscape pattern Index,Arc GIS and Pearson correlation analysis were applied to analyze the relationship between the dynamic change of landscape pattern and the change of surface runoff in the main urban area of Xi’an.Tarting from the optimization of natural landscape and seminatural landscape pattern,combining urban landscape pattern planning research with urban waterlogging prevention,this paper attempts to raise the landscape pattern planning strategy based on stormwater management.The process and results of this research show that:(1)From 2000 to 2019,the landscape pattern of the main urban area of Xi’an showed a developing trend of high connectivity and high aggregation,regular patch shape,homogenization and stabilization,and the patch spread decreased.At the same period,the surface runoff depth increased year by year,however,the increase of runoff depth showed a downward trend with the time.In2000—2005,2005—2010,2010—2015,2015—2019,the increment of runoff depth was 4.99,4.95,3.55,and 3.33 mm respectively,indicating that retention effect of landscape pattern on surface runoff increased gradually.(2)At the level of landscape,the proportion of maximum patch area and patch connectivity index are observably and positively related to the depth of surface runoff,indicating that the larger and more concentrated the artificial landscape patches are,the wider the range of surface runoff is;however the landscape shape index showed a significant negative correlation with the depth of surface runoff,indicating that the more complex the shape of natural landscape patches is,the lower the yield of surface runoff is.(3)At the level of landscape type,the change rate of landscape pattern index is observably correlated with the annual growth rate of surface runoff.The change rate of artificial landscape index such as construction land is significantly and positively related to the annual growth rate of surface runoff.On the contrary,the change rate of natural landscape index such as green space,cultivated land and water area is negatively related to the annual growth rate of surface runoff.Combined with the land use transfer matrix shows that the more complex the shape of natural landscape patches is,the more beneficial it is to reduce precipitation interception and effectively slow down and reduce surface runoff.(4)Landscape planning under the background of stormwater management starts from the pattern of urban ecological security,and combine with stormwater regulation and storage measures,including the construction strategy of urban scale stormwater landscape security pattern,the planning strategy of stormwater prevention and control unit at the block scale and the site regulation and storage strategy of landscape sponge at the site scale.(5)Landscape pattern optimization can give completely play to the multiple composite functions of urban natural landscape,seminatural landscape and artificial landscape,such as stormwater regulation and storage,drought and flood regulation,landscape construction and ecological protection,and form a stormwater management ecosystem network with mutual linkage of landscape pattern.Give play to the overall benefits of urban drainage and waterlogging reduction and promote the coordinated development of social,economic and ecological benefits. |
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