| With the progress of society and the development of the economy,the natural landscape of the city is reduced by high-intensity human intervention,and the frequency of extreme weather is increasing.The infighting disaster caused by heavy rain often occurs,which ultimately causes significant loss of life and property to citizens.Because the green space has special ecological value in the process of urban construction and development,its storage and regulation function play an important role in realizing the utilization of rainwater resources,effective control of runoff,and solving the problem of internal disasters.Therefore,researches on green space and runoff control and rational use of water resources has become inevitable.This paper taking the central area of Luohe as the research object,based on field field survey,aerial image of unmanned aerial vehicle,map of urban elevation,surface point cloud data,urban master plan,urban green space system planning and other data,using SWMM model,using GIS geographic information system,analysis the changes of runoff characteristics under the local green space landscape pattern,different underlying surface and different rainfall return periods in the central urban area initially.And then revealed the influence of green landscape pattern on runoff changes,and finally proposed the strategy of urban green space pattern optimization and runoff control.The conclusions are as below:(1)Urban green space has a certain mitigation effect on the generation of rainwater runoff.The green space mainly plays an auxiliary role in reducing urban rain and flood through three ways: soil infiltration,rainwater savings and runoff delay.Urban green space is necessary in the future construction of urban runoff control.(2)Urban green space layout has an important impact on the distribution and regulation of storm water runoff.In the case of a certain green space rate,the green space affects the city's rain and flood storage capacity through the distribution pattern and structural characteristics.Therefore,according to the different types of green space,scale and structure to optimize,combined with water bodies and other permeable elements to build a reasonable spatial layout,this way improve the city's rain and flood storage capacity,and achieve the goal of efficient control of runoff.(3)By the hydrological analysis function of GIS and the simulation analysis of SWMM model,the variation law of runoff is obtained: the total runoff and runoff peaks increase with the increase of rainfall return period when the underlying surface impervious area ratio is the same.When the rainfall return period is consistent,the total runoff and peak value increase with the increase of urban surface impervious area;the in-depth study of surface impervious area ratio is 35%,55%,75% of the sub-catchment area total runoff.The change in volume and peak value found that the increase in the ratio of the impervious area to the surface gradually decreased.There is a convergence effect between the increase of runoff coefficient and the increase of runoff peak in the study object;the total runoff and peak runoff increase under the adjacent return period have different rules with different surface: the total runoff increase under the adjacent return period is negatively correlated with the area ratio of impervious area.The increase of peak runoff is positively correlated with the ratio of impervious area.The change of rainfall under different return periods affects the numerical change of runoff peak and runoff total.The change area is the same as the change trend of rainfall,and the added value maintains a certain consistency with the increase of rainfall. |
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