【作者】 朱永杰；

【导师】 毕华兴；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2016， 硕士

【摘要】 城市草坪能通过截留、消减暴雨径流,可有效缓解城市内涝灾害,减轻城市排水管网压力。本文以我国南方和北方的代表性草坪绿地(狗牙根和高羊茅)为研究对象,并以裸地为对照,利用人工模拟降雨装置,通过降雨产流试验,研究了两种草坪绿地在2个植被覆盖度(0%、90%)、3个雨强(30、60、90 mm/h)、3个坡度(5°、10°、200)情况影响下的径流产生规律,分析了两种绿地对降雨形成的径流的削减效果,旨在为海绵城市建设提供理论和技术支撑。主要研究结果如下：(1)两种草地产流过程规律相似,降雨进行一段时间后才开始产流,初始产流时间从54’00"到2’05"不等,随着降雨的继续产流速率不断增大,出现径流峰值流量,流量峰值为182～1200 mL/min,达到峰值流量后,在降雨结束前产流速率就稳定在峰值上下波动。初始产流时间：两种草地及其裸地初始产流时间均随着坡度和降雨强度的增加而提前。随降雨强度增加,狗牙根草地初始产流时间从34’43"提前至23’25",其裸地由25’39"提前至7’22",高羊茅草地由52’45"提前至40’46",其裸地由19’20"提前至8’26";随坡度增加,狗牙根草地初始产流时间从48’18"提前至14’15",其裸地由31’15"提前至4’26",高羊茅草地由1h15’提前至24’17",其裸地由28’28"提前至4’10"。与裸地相比,草地对初始产流时间有很好的延缓作用。径流峰值流量出现时间(以下称为峰现时间)：峰现时间随降雨强度和坡度的增大而提前,最大提前75 min,平均提前37.5 min；与裸地相比,草地对峰现时间有很好的延缓作用,狗牙根草地比裸地平均延缓44 min,高羊茅比裸地平均延缓31 min草地对峰现时间的延缓作用在降雨强度较小、坡度较缓的情况下效果较好。径流峰值流量(以下称峰值流量)：相同条件下裸地峰值流量明显大于草地,草地与裸地差异极显著；随着坡度和降雨强度的增加,草地及其裸地的峰值流量逐渐升高,狗牙根草地变化范围为203～750 mL/min,对应裸地为380～1200 mL/min,高羊茅草地为182～871 mL/min,对应裸地为361～1070 mL/min。(2)两种草地径流总量随降雨强度和坡度增加递增明显,狗牙根草地由22.58 L (5°、30mm/h)上升为33.77L(90mm/h、20°),增幅为49.56%,高羊茅草地从16.96L(30 mm/h、5°)增加到30.54 L (90 mm/h、20°),增幅为80.07%；灰色关联度分析得到降雨强度和坡度对两种草地径流量影响关联度分别为0.61、0.60和0.62、0.51,降雨强度对草地径流总量的影响程度比地面坡度更大。(3)草地对径流削减作用效果显著；狗牙根草地对场降雨径流系数值最大削减59.02%,平均削减47.54%,高羊茅草地对场降雨径流系数最大削减64.18%,平均削减56.90%；总体来看,对径流总量削减率是随降雨强度和坡度增加而减小,呈幂函数递减的关系。狗牙根对径流量的最大削减率为59.04%,最低为37.65%,平均削减47.76%,高羊茅对径流量的削减率变化范围为47.13%-63.41%,平均削减57.23%。拟合狗牙根草地和高羊茅草地对径流削减率与坡度和降雨强度回归方程,试验条件下削减率模拟值与实测值绝对误差在10%以内,模型的纳什效率系数分别为0.69和0.18,可信度较好。狗牙根和高羊茅草坪绿地(坡度为0)对1941-2010年北京地区代表站60分钟年最大降雨强度削减率范围分别为47.92%～67.50%和55.04%-68.16%。更多还原

【Abstract】 City lawn can effectively alleviate the city waterlogging disaster, alleviate the pressure of city drainage pipe network through its function of interception, reducing surface runoff. In order to study the runoff process of two kinds of green space and analyze the effect of green space on storm runoff reducing at different vegetation coverage(0%、90%)、different rainfall density (30、60、90mm/h) and different slope degree (5°、10°、20°) by using artificial simulated rainfall device, this paper sat the representative green space in the south and the north of China as the study object and the bare land as CK, which aimed at to relieve urban waterlogging disasters and alleviate pressure on urban drainage network, and sponge urban construction to provide theoretical and technical support. The main results are as follows:Two kinds of grassland runoff process law is similar, runoff began to produce after a period of time raining, runoff rate increased as the rainfall continue, and finally tend to be stable. The initial runoff generation time range from 2’05"to 54"00", there is a peak flow with the increasing of runoff producing rate, the runoff rate is stable at 182-1200 mL/min after the peak flow rate is reached..Initial runoff-yielding time:Grassland, bare land initial runoff-yielding time shortened with increasing of rainfall intensity and slope. Cynodon dactylon (L.) Pers grass land (which referred to as C land) initial runoff-yielding time from 54’00"(30 mm/h,5°) shortened to 13’30"(90 mm/h,20°) and its bare land from 49’58"(30 mm/h,5°) shortened to 2’18"(90 mm/h,20°); Festuca elata Keng ex E. Alexeev grass land (which referred to as F land) initial runoff-yielding time from 1h24’(30 mm/h、5°) shortened to 20’51"(90 mm/h、20°) and its bare land from 45’24"(30 mm/h、5°) shortened to2’05"(90 mm/h、10°).Peak current time advanced with the increase of rainfall intensity and slope, the maximum was shortened 75 min and shortened 37.5 min averagely. Compared with bare land, grassland has a good delay function, C land averagely need 44 minutes peak current time more than its bare land, F land averagely need 31 minutes peak current time more than its bare land; The delayed effect of grassland on the peak current time was better in the case of smaller rainfall intensity and slow slope.Bare land peak flow under the level of 0.05 was significantly higher than that of grassland; The peak flow of grassland and its bare land increased gradually with the slope and rainfall intensity increased, C land range for 203-750 mL/min and its bare land range for 380-1200 ml/min, F land range for 182-871 ml/min, its bare land range for 361-1070 ml/min.The total runoff volume of the two types of grassland increased significantly with the increase of rainfall intensity and slope. C land total runoff volume from 22.58 L(30 mm/h、 5°)up to 33.77L(90mm/h、20°), the increase rate was 49.56%, while F land from 6.96 L(30 mm/b、5°)up to 30.54 L(90 mm/h、20°), the increase rate was 80.07%; The influence correlation degree of rainfall intensity and slope on the two types of grassland runoff was 0.61、0.60 and0.62、0.51 respectively by the ways of grey relational grade analysis, which means the effect of rainfall intensity on the total volume of grassland was greater than slope.The effect of grassland on runoff reduction was significant; The C land maximum can reduce runoff coefficient 59.02% and averagely reduce 47.54%, F land maximum can reduce runoff coefficient 64.18%and averagely reduce 56.90%; The reduction rate of total runoff is decreased with the increase of rainfall intensity and slope gradient, which decreased as a power function. Runoff reduction rate of C land up to 59.04%(30 mm/h、 5°), the average reduction of total runoff was 47.76%, The maximum runoff reduction rate of F land was 63.41%, minimum was 47.13%. The regression equation about reduction rate and slope and rainfall intensity of two grassland were analyzed, the simulated values of the reduction rates are close to the measured values under this experimental conditions and the absolute error is less than 10%.Nash-Sutcliffe efficiency coefficient of two model equation is 0.69 and 0.18. Cynodon dactylon (Linn.) Pers lawn and Festuca elata Keng ex E. Alexeev lawn can respectively reducing the runoff volume at 47.92%～67.50% and 55.04%-68.16% for 60 minutes on behalf of Station in Beijing between 1941～2010 years.更多还原