Seepage Simulation And Design Optimization Of Rain Garden

As one of the important components of urban stormwater management system,the rain garden is not only beneficial to improving urban waterlogging and purifying rainwater quality,but also beneficial to ameliorating urban ecological environment.Consequently,it is of great significance to carry out research related to urban rain gardens to enhance the ability of urban stormwater management and improve the quality of life of residents.In the interest of quantitatively evaluating the seepage performance of rain garden and its absorption effect on stormwater,this paper optimizes the calculation scheme of Horton infiltration model on the basis of the equivalent permeability principle.Meanwhile,taking a rain garden in Hebi City as the engineering background,this paper combines the optimized Horton model calculation scheme and SWMM software to construct the seepage model of rain garden.Furthermore,this paper presents the systematic research of seepage performance and design and optimization of rain garden,with achieving the main research contents and results as follows:(1)During the practical application process,Horton model revealed the defect of lack of sufficient consideration of soil moisture content,which led to the infiltration rate calculated by the model being less than the actual soil infiltration rate.In this regard,this paper optimized the calculation scheme of Horton model adopting the equivalent permeability principle.In addition,by virtue of empirical analysis,this paper demonstrated that the infiltration curve obtained by the optimized model calculation scheme had a higher fitting degree with the actual infiltration curve,showing a wider engineering application range.(2)Taking a typical rain garden in Hebi City as the research object,this paper constructed a rain garden model in combination with the optimized Horton model calculation scheme and SWMM software.Based on that,this paper further carried out the research related to the internal seepage performance of rain garden and the rainwater absorption effect.By simulating the rain garden under typical working conditions,the research results indicated that the seepage performance of the rain garden gradually decreased with the increase of rainfall intensity and duration.Moreover,in the existing rain gardens,the design scheme represented by sponge facilities reflected unreasonable defects,lacking consideration for typical rainfall situations.Also,under the context of partial typical rainfall conditions,the seepage performance of the rain garden was not consistent with the requirement of runoff reduction rate above 15%.(3)Committed to solving the problem that the seepage performance of the rain garden does not comply with the specified requirements in the typical rainfall conditions,this paper selected the design parameters related to the seepage performance of the rain garden to optimize the seepage performance of the rain garden accordingly.The research results indicated that:a)changing the sinking depth was the top priority to improve the seepage performance;b)the effect of changing the filler and increasing the area ratio is poor.At the same time,by introducing the two parameters of sinking depth and area ratio,this paper further drew the reference table of the influence of structural design parameters of rain garden in Hebi City on seepage performance.Based on this,this paper proposed that only by adopting the design area ratio and the sinking depth greater than the value corresponding to the 15%runoff reduction rate in the reference table can the similar rain gardens in Hebi City fully conform to the requirements related to seepage performance design under typical rainfall conditions.Furthermore,this paper provided a clear design reference scope for the future construction of rain gardens in Hebi City.