| The rapid development of urbanization leads to the dilemma of water resources reduction and pollution degradation in cities.At the same time,the overloaded operation of the urban infrastructure makes the city face the threat of severe rain flood and waterlogging.Lake is not only an important water resource in the city,but also an important carrier of urban rainwater facilities construction.Lake park is the intersection of urban green space system and urban lake system,which carries the important functions of reducing urban waterlogging and rainwater and protecting lake resources.The layout and construction of lake parks are faced with great challenges under the conditions of intensive land use,limited construction space and complex site conditions.In recent years,scholars in China and abroad have discussed the regulation and storage effect of water system and green space on urban stormwater from the aspects of urban water system connectivity,urban green infrastructure construction and sponge city construction,etc.,and with the help of hydrological model software,it is used to simulate and predict the rainwater process,the layout of rainwater facilities and the construction evaluation of rainwater system.Wuhan is a typical lake water system city.this study urban lake water system and urban green space system of urban rain flood regulation of synergy in Wuhan city center as the research scope,to city water system and urban green space system intersects the rain flood storage patches-lake park as the research object,explore urban rain flood regulation of lake park and lake protection construction strategy.The main research contents and results of this paper are as follows:(1)The SWMM model of the central city of Wuhan was constructed to simulate the three-hour rainfall inundation in the central city of Wuhan under the rainfall intensity of 2,5,10,50 and 100 years of the rainstorm return period.The results show that with the increase of rainfall intensity,the urban total runoff,external flood,drainage volume of discharge outlet and total storage volume of node increase.The number of overflow nodes increases,the occurrence time of overflow nodes is earlier,and the overflow time is longer.However,there is no linear correlation between the overflow depth and the overflow time and the maximum overflow velocity.The depth of overflow is greatly affected by the underlying surface of the city.Therefore,in this research,five indexes of overflow time,overflow depth,overflow speed,impervious rate of underlying surface and road density were selected from the aspects of risk,vulnerability and vulnerability,and a storm flood inundation risk assessment system was constructed for the central city of Wuhan.And the regions with high risk of rain and flood in different rainstorm return periods were identified.(2)The stormwater storage potential of urban lake system and urban green space system in the central district of Wuhan were calculated.The results show that the regulation and storage volume of the urban lake system reaches 110*106m3,and the rainwater and flood regulation and storage volume of the urban green space system reaches 6.15*106m3,which can receive the highest rainfall of 3 hours under the intensity of one rainstorm in 20 years.Urban lake water system,urban green space system elements were gradually added to the initial SWMM model of Wuhan city center.The results show that the urban lakes drainage outlet of urban rain flood storage can only reduce the city traffic,and can reduce the total amount of runoff and infiltration of the city,and the synergy of urban green space system and urban lakes water system can effectively reduce the rain runoff flood peak values,and delay the peak time of runoff.(3)The lake and green coordinated stormwater storage system in the central urban area of Wuhan was constructed.The system takes urban drainage system as matrix,urban lake system and urban green space system as stormwater diversion corridor,and urban lake park as the terminal patch of runoff rainwater regulation and storage,and establishes a complete stormwater runoff drainage and storage network.And the system also connects urban lake water system gallery with urban rainwater runoff path,urban green system gallery with green patch density and vegetation coverage,regulates the opening rate and form of boundary of urban lake parks,and ensures the smoothness of rainwater and flood runoff drainage and storage network.(4The influence of urban general layout,the lake water body elements,green lake park plant elements,road traffic,landscape architecture elements such as spatial layout of urban lake park rain flood storage efficiency was analyzed.The results showed that the water in the overall arrangements for the area proportion(54.60%),the largest lake water area and park area there is a significant positive correlation relationship,The average distance from the boundary of lake park to the boundary of lake water is 58.37 m,49% of the revetment is natural revetment,and there is a significant positive correlation between the green planting area and the park area,while there is no significant correlation between the road paving area and the total area of lake park and the green space area.By using the orthogonal test method,with the help of SWMM model,the abstract model of lake park was constructed by five level values of three factors: water area ratio(25%,40%,55%,70%,85%),green road area ratio(3/1,6/1,9/1,12/1,15/1)and vegetation coverage(20%,35%,50%,65%,80%).The rainwater runoff and water quality of the lake park were simulated to explore the threshold of landscape layout elements in the lake park.The results show that the water area of the lake should be controlled below 40%,the area ratio of green space and road should be 13/1,and the higher the vegetation coverage is,the more beneficial the rainwater storage in the park.(5)Urban lake park storm water storage development planning strategy including boundary and internal two aspects was established.The boundary planning of urban lake park should first determine whether the surrounding environment of the lake is suitable for the lake to accept runoff and rainwater,and then regulate the layout of landscape elements of the park to maximize its ecological and landscape benefits.Water elements should be ecological first,lake protection priority;The land used for planting afforestation should meet the demand,and pay equal attention to function and aesthetics;Road paving elements should be innovative form,update technical materials;Rainwater facilities should be clearly positioned and the regulation and storage system should be improved. |
