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重庆山地公园子汇水区产流特征与雨洪利用改造策略
刘家琳1, 李媛媛2, 张建林3
1.西南大学园艺园林学院,副教授, liujialincq1986@qq.com;2.雄安城市规划设计研究院有限公司;3.西南大学园艺园林学院,教授
摘要:
重庆主城区山地公园外排雨洪与暴 雨水问题不容忽视,针对其产流量化特征以 及相应的雨洪利用策略的研究较缺乏。以重 庆主城区四种典型基址类型的12例山地公园 为研究对象,基于SWMM建立山地公园现 状雨洪模型,在25 mm、50 mm、127 mm、 166 mm降雨下,对138个子汇水区进行产流 模拟分析,得出25 mm、50 mm降雨下,子汇水 区土壤基本均未饱和,不透水率与产流量呈 线性关系,127 mm、166 mm降雨下,随雨量 的增加,不透水率与产流量的线性拟合度减 弱,饱和入渗率与产流量的线性拟合度增强。 25 mm、50 mm、127 mm、166 mm降雨下, 公园综合径流系数分别为0.313、0.342、0.529 和0.617。雨洪利用策略以子汇水区为基本管 控单元,针对6种典型的子汇水区类型,提出 不同雨型控制目标下相应的低影响开发设施 布局策略,并基于产流量分析结果对渗透设 施(简易型生物滞留设施、渗透塘)规模计算 公式进行细化,研究结果为海绵城市建设和城市双修背景下,山地公园汇水区现状雨洪管理优化 改造提供实践指导参考。
关键词:  风景园林  城市山地公园  SWMM模型  产流特征  低影响开发
DOI:10.13791/j.cnki.hsfwest.20190606
分类号:
基金项目:国家自然科学基金青年科学基金项目:城 市山地公园低影响开发系统布局构建研 究——以“海绵城市”建设试点城市重庆 为例(51708452)
Analysis on Surface Runoff Property and Stormwater Utilization in Urban Mountain Parks in Chongqing
LIU Jialin,LI Yuanyuan,ZHANG Jianlin
Abstract:
The stormwater in most urban mountain parks in Chongqing City has not been utilized by planning and design. In the Southwest Region of China under subtropical monsoon humid climate, little research has been done to study surface runoff characteristics and stormwater utilization in urban mountain parks. This study focused on four types of urban mountain park (hilltop subtype, hillside subtype, piedmont subtype and valley substype). Three typical cases in each subtype resulted in 12 typical cases were focused in this study. These 12 parks were divided into 138 subcatchments. Stormwater management models were created by SWMM to analyze the surface runoff quantity and the comprehensive runoff coefficients of the s ubcatchments. T he s ubcatchments p roperties i n SWMM were s et a s b elow. 1) T he a rea, width, slope and the impervious rate properties of each subcatchment were set based on the Auto CAD topographic map data. 2) Horton model is adopted for the infiltration model in SWMM. The saturated infiltration rate of the topsoil (thickness of 30 cm) under four types of vegetation (ground cover subtype, shrub and ground cover subtype, arbor and ground cover subtype, arbor, shrub and ground cover subtype) in each park was measured in the laboratory by the ring cutter sampling method. The saturated infiltration rate of the pervious portion of each subcatchment was determined by the area weighting method according to the saturated infiltration rate of the topsoil under the four types of vegetation. The initial infiltration rate of the pervious portion of the subcatchment was determined based on another local research result of the initial infiltration rate (rainfall interval 2-7 days) of the urban green space in Chongqing. The infiltration attenuation coefficient was according to the model default value. 3) The manning’s n for overland flow over the impervious portion and the depth of depression storage on the impervious portion were determined by the model recommended value of the impervious concrete. The manning’s n for overland flow over the pervious portion and the depth of depression storage on the pervious portion were based on the area weighting method by the model recommended value of different vegetation cover types. 4) The percent of the impervious area with no depression storage was set by the model default value. The simulated results of the runoff coefficient of the pervious surface were close to the local experimental measurement results on the pervious surface with similar slope, which shows that simulated results of the models could be reliable. The result shows that under 25 mm and 50 mm rainfall events, the subcatchment in urban mountain parks were almost unsaturated and there was linear relationship between impervious rate (X) and runoff quantity (Y). Under 25 mm rainfall event, the linear formula is Y=235.7X-0.702 (R2=0.993), under 50 mm rainfall event, the linear formula is Y= 454X+23.639 (R2=0.920). Under 127 mm and 166 mm rainfall events, the linear fitting degree between impervious rate and runoff quantity reduced (R2= 0.363 under 127 mm rainfall event, R2= 0.294 under 166 mm rainfall event), while the linear fitting degree between saturated infiltration rate and runoff quantity increased (R2= 0.450 under 127 mm rainfall event, R2= 0.570 under 166 mm rainfall event). The result shows that the comprehensive runoff coefficients of all subcatchments were increased with the increased rainfall events. The comprehensive runoff coefficients of urban mountain parks were obtained by the area weighting method, which were 0.313 (under 25 mm)、0.343 (under 50 mm)、0.526 (under 127 mm) and 0.614 (under 166 mm). These values are bigger than the reference value provided by the Outdoor Drainage Design Standard GB50014-2006 (2016 vision), which were probably due to the slope and the impervious surface construction in these local parks. For the runoff control and utilization strategies, the basic runoff control unit is the subcatchment. Based on location, surface composition, slope, impermeability and the outlet layout of the subcatchments, all 138 subcatchments were divided into 6 types: paved square type, vegetation cover type I and II, mixed cover type I, II and III. This study provided the layout strategies of low impact development facilities for the 6 types subcatchments under different rainfall control objectives and pointed out the revised calculation formula for infiltration facilities (simple bio-retention area and pervious retention pond) for the urban mountain parks in Chongqing City. This study has the practical value for the landscape renovation of the subcatchments in urban mountain parks under the background of sponge city development in Southwest China.
Key words:  Landscape Architecture  Urban Mountain Parks  SWMM  Surface Runoff Property  Low Impact Development