基于DRAINMOD模型的雨水花园运行效果影响因素

为研究雨水花园对暴雨径流水文调控效果受不同设计参数的影响,在试验研究的基础上,利用排水模型DRAINMOD分析了雨水花园长期运行效果受其蓄水层深度、汇流面积比以及降雨特征等因素的影响。模型测试结果显示,DRAINMOD可以较好地模拟雨水花园内部水文过程;长序列（1951—2007年）模拟结果发现,试验雨水花园对暴雨径流量削减率的年均值为18.5%,经介质净化的水量占雨水径流总量的76.1%;雨水花园蓄水层深度超过某一临界值后对其滞留效果没有影响;汇流面积比增大,排水量和溢流量均增大;在雨水花园内部增加30 cm反硝化作用蓄水层后,排水量下降了19.2%,雨水花园对径流量的削减率提高到33.5%。可见,增加内部蓄水层后雨水花园对水量削减和污染物浓度去除都具有积极作用。     

雨水花园集中入渗对地下水水位与水质的影响

作为低影响开发（Low Impact Developmet, LID）措施之一,城市雨水花园集中入渗雨水径流可增加对城区地下水的补给。根据一现场监测试验,研究了长期（监测期3年）及短期（降雨3天内）雨水花园入渗点及对照点地下水位与水质的变化,分析了集中入渗的效果和影响范围。结果表明:① 雨水花园对入渗区地下水位产生了显著影响（α=0.01）;② 氨氮（NH₄-N）在3年及雨后3日的观测值均显著小于对照值;总氮（TN）指标在短期增加显著,长期均值增加不显著。③ 硝态氮（NO₃-N）浓度在降雨后有所升高,但不显著,几个观测点浓度有增有减;总磷（TP）浓度的短期值和长期均值有增有减。对于类似研究区地下水位在2~3 m的情况,集中入渗雨水径流可有效补给地下水,对氮素影响明显,对磷影响有限。     

含碎石紫色土坡面降雨入渗和产流产沙过程

在室内土槽模拟降雨试验基础上,观测了具有不同碎石体积含量紫色土的降雨入渗地表产流产沙量以及细沟间径流和细沟径流的流速,以期建立碎石含量与土壤流失的定量关系。研究结果表明:土壤中碎石混合对降雨入渗有正负两方面的影响,当碎石含量为20%~30%时,碎石的存在增强土壤入渗能力,当碎石含量提高到30%时,土壤的入渗能力被削弱。土壤中碎石混合通过不同的作用机制对坡面细沟间径流流速和细沟径流流速产生不同的影响,随着碎石含量的增加,细沟间径流平均流速逐渐增加,细沟径流的平均流速逐渐降低。土壤中碎石混合通过改变土壤的物质组成和结构,增强土壤的抗蚀性和抗冲性,随着碎石含量的增加,径流含沙率和土壤流失量显著降低,土壤流失比与碎石含量呈极显著指数负相关关系。     

含碎石紫色土坡面降雨入渗和产流产沙过程

在室内土槽模拟降雨试验基础上,观测了具有不同碎石体积含量紫色土的降雨入渗地表产流产沙量以及细沟间径流和细沟径流的流速,以期建立碎石含量与土壤流失的定量关系。研究结果表明:土壤中碎石混合对降雨入渗有正负两方面的影响,当碎石含量为20%~30%时,碎石的存在增强土壤入渗能力,当碎石含量提高到30%时,土壤的入渗能力被削弱。土壤中碎石混合通过不同的作用机制对坡面细沟间径流流速和细沟径流流速产生不同的影响,随着碎石含量的增加,细沟间径流平均流速逐渐增加,细沟径流的平均流速逐渐降低。土壤中碎石混合通过改变土壤的物质组成和结构,增强土壤的抗蚀性和抗冲性,随着碎石含量的增加,径流含沙率和土壤流失量显著降低,土壤流失比与碎石含量呈极显著指数负相关关系。     

海绵城市雨水径流集中入渗对土壤和地下水影响研究进展

中国海绵城市研究的热点主要有海绵城市的内涵、目标、内容和效果,而对可能产生的不利影响缺乏研究。近几年雨水径流集中入渗类设施在中国海绵城市建设中得到广泛应用,但对集中入渗的影响及风险研究严重滞后,不利于中国海绵城市建设的健康发展。因此,从海绵城市雨水径流集中入渗与传统入渗的差异切入,分别从集中入渗对土壤污染与地下水水量水质的影响、集中入渗对土壤与地下水影响的数值模拟、集中入渗污染物的累积效应与风险评价研究等方面,综合评述国内外的研究进展与不足。建议今后从以下4个方面开展进一步研究:①土壤污染风险及其影响因素;②雨水径流集中入渗的土壤污染累积效应;③地下水污染风险预测;④降低地下水污染风险的措施。     

前期土壤含水量对红壤坡面产流产沙特性的影响

利用田间人工模拟降雨试验,研究了前期土壤含水量对两种红壤坡面降雨入渗、产流和产沙特性的影响.结果表明:前期含水量越高,两种土壤都是产流越快,达到稳定径流和入渗的时间越短.低含水量区(干态和稍干),两种土壤的径流系数和入渗率都与降雨时间呈线性关系,并在60 min内达不到稳定.高含水量区(稍湿和湿态),两种土壤的径流系数、入渗率及产沙速率与降雨时间关系都符合Boltzmann(玻耳兹曼)方程;第四纪红粘土发育的红壤稍干态和红砂岩发育的红壤干态下的产沙速率在整个降雨过程中变化不明显,并都维持在较低水平;第四纪红粘土发育的红壤干态和红砂岩发育的红壤稍干态下的产沙速率随着模拟降雨的进行而大致以线性关系增大.土壤前期含水量越高,两种土壤坡地累tk积入渗量都越小,雨水转化为土壤水分的比率亦越小.     

岩溶泉域降雨径流水文过程的模拟——以重庆金佛山水房泉为例

通过地貌、水文地质、土壤、植被、地下洞穴管道等实地调查,以及示踪试验确定水房泉泉域范围和地下水文系统特征,并通过代表性点的土壤入渗试验、降雨和流量监测以及DEM数据等获得泉域水文模型所需的面积、结点高程、入渗率、糙率、管道长度、含水层孔隙度、出流系数等参数。选择SCS径流曲线模型估算地表产流,利用SWMM模型模拟泉域对场降雨的径流响应过程。通过运行模型,与实测流量比较,结果显示模拟曲线与观测流量曲线吻合较好,用于校正和验证的两场降雨产流的模拟误差分别为9.5%和12%,表明SWMM可应用于岩溶区以管道流为主要排水系统的含水介质的模拟。     

海绵城市之含水层补给砾石桩与垂直渗透导管LID工法新设计

海峡两岸之都会地区快速发展,使不透水地表面积增加,加上降雨型态逐渐改变,都市防洪必须采取更多元的策与手段,以因应此一趋势所造成的挑战。近年来,国际间常采用低冲击开发(low impact development,LID)之入渗工法为都市防洪的手段。低冲击开发措施,是利用开发区域其中一小部分土地,以小单元分布式之入渗方式削减地表径流,恢复该区块之原始水文循环状态,以提升地下水补注、降低热岛效应,以实现海绵城市之概念。本研究以台中市卵砾石地层为研究对象,导入上述低冲击开发概念,以办公大楼旁之空地,设置一植生滞留池并加入砾石桩,利用砾石桩之高渗透性,将自大楼屋顶收集之降雨径流,快速导入含水层中,进而补注地下水。人为注水试验结果显示,植生滞留池于设置砾石桩后,入渗率可提升约10倍,而自然降雨事件入渗率效果更加显著。以暴雨径流管理模式(storm water management model,SWMM)评估植生滞留池设置前后之功效,植生滞留池设置后,于5年重现期距降雨事件下,可达到86%出流体积削减,也降低5%洪峰流量,设置砾石桩后,于自然降雨事件中植生滞留池皆未产生地表出流。而以停车场铺面区域为例,加入垂直式渗透导管改造后之透水铺面饱和入渗率计算值可增加18~35倍,模拟子集水区与铺面改造情境下加入垂直式渗透导管,考虑设置数量与削减径流百分比,其设置面积10%时发挥最佳削减效益,以连锁砖改造为植草砖之情况设置垂直式渗透导管面积达10%与现况情境相较之下,于五年重现期降雨可削减15%以上之地表径流体积。     

不同坡度植被边坡降雨入渗和径流侵蚀规律的试验研究

为研究不同坡度植被边坡降雨入渗和径流侵蚀的规律,开展大型边坡模型降雨试验,对边坡含水率、水土流失等参数进行实时监测,量化分析坡度对边坡雨水入渗、坡面径流和土壤侵蚀的影响。结果表明：在持时为4 h、降雨强度为60 mm/h持续降雨条件下,1:2、1:1.75、1:1.5裸土边坡累计雨水入渗量分别为同坡度植被边坡的70.6%、80.4%、92.3%,植被覆盖会加快雨水入渗速率,增大边坡累计雨水入渗量。植被边坡坡度越小,雨水入渗速率越快,累计雨水入渗量越大,而裸土边坡则相反。植被覆盖可有效降低坡面径流速率、减少累积径流量,边坡坡度越小,减流效果越显著,1:2、1:1.75、1:1.5植被边坡对比同坡度裸土边坡分别减少径流量53.11%、32.56%、17.73%。植被边坡水土流失含泥沙量均不足0.1%,植被可有效抑制坡面土壤侵蚀,而裸土边坡坡度越大坡面土壤侵蚀越严重,1:2、1:1.75、1:1.5裸土边坡单位面积侵蚀土壤质量分别为3.623、5.710、11.295 kg/m²,水土流失含泥沙量分别为3.06%、4.29%、7.34%。根据试验结果拟合得到裸土边坡产泥...     

植草沟径流调控效果对关键设计参数的响应规律模拟

为分析道路低影响设施植草沟主要设计参数对地表径流调控作用的影响规律,应用一套耦合了水文和水动力过程的数值模型,研究各设计参数对植草沟径流控制作用的调控效果,经验证模型模拟精度可满足研究要求。模拟结果表明:植草沟具有削减洪峰洪量、推迟峰现时间的作用。且溢流井位于入水口上游侧,横、纵坡坡度越缓时,植草沟径流控制效果越显著。溢流井位置改变时径流控制效果差值达2%~10%,峰值削减差异为13%~28%;横坡坡度从1/3~1/7变化时,径流控制率提高4%~13%,峰值削减效果提升6%~23%;纵坡坡度从0.5%~0.3%变化时,径流控制率提高7%~16%,峰值削减效果提升12%~29%。数值模拟得出各设计参数的影响规律,可用于指导植草沟的规划设计,为其推广应用提供参考。     

Modeling hydrological responses of karst spring to storm events: example of the Shuifang spring (Jinfo Mt., Chongqing,China)

Reproduction of hydrographs at karst springs has been an approach of understanding the karst aquifer, which normally acts as drains for the groundwater flow. However, its numerical modeling is difficult since factors for the internal geometry and connectedness are unknown and hard to quantify. Hydrographs of the karst aquifer with well-developed conduits in Shuifang spring catchment were obtained from the automatic gauging station at the spring orifice. Data as to the conduit system were also obtained based on results and analyses of tracer tests. With these data, the hydrological responses of Shuifang spring to storm events were simulated by storm water management model (SWMM) developed by USA EPA (Environmental Protection Agency). Nash–Sutcliffe efficiencies are used to compare the computed flow to the observed, which are 0.95 and 0.92 for calibration and validation. SWMM was verified and applicable in karst conduit drainage system. The model illustrated correctly quick recharge through conduits and slow and low inflow from the fissured aquifer matrix. The SCS-CN (soil conservation service-curve number) infiltration method was used for computation of losses and runoff. Field tests indicated that permeability was extremely high but different in karst area, which was less sensitive to the computed runoff when exceeded the common value provided by SWMM. Therefore, an improved quantitative infiltration model for karst area will make SWMM possible to be a useful tool for assessing and reproducing spring hydrographs.     

长三角地区典型海绵设施水文效益试验研究

开展不同海绵设施在中国长三角气候模式下的水文效益研究, 对增强城市应对内涝能力从而提高城市对变化环境的适应性具有重要科学意义。选择国家首批海绵试点城市镇江海绵基地4种典型海绵设施作为研究案例, 采用径流系数、削减率、削峰率及洪峰流量等指标, 评估场次降雨与海绵设施出流相关性, 分析海绵设施在不同降水量级和降雨雨型下的水文性能, 以及运行时间对海绵设施水文效益的影响。结果表明: ①透水铺装类海绵设施的降雨—径流关系呈单一式; 而绿植类则表现为分段式, 即在场次降水量超过一定临界暴雨量之后关系线发生转折, 其中平均径流系数增加了8.4~38.5倍, 平均削峰率和削减率分别减少了50.4%和44.6%。②暴雨条件下不同海绵设施的产流能力和洪峰流量最大, 对径流总量消减能力及洪峰流量削减能力最弱, 且从暴雨到大雨变化规律比大雨到中雨变化规律更显著。③海绵设施的水文性能受到降雨雨型、平均降雨强度和最大单位降雨强度等因子多重复合影响。除雨水花园外, 其他海绵设施的径流系数对上述影响因子变化最为敏感, 洪峰流量次之, 削减率第3, 削峰率的敏感性显著低于前面三者。④车行透水砖运行1 a后, 其产流能力与洪峰流量分别显著增加1.7~2.1倍和1.9~2.5倍; 径流控制能力显著减弱, 其中消减能力降低了16%。     

Behaviour of chromium(VI) in stormwater soil infiltration systems

The ability of stormwater infiltration systems to retain Cr(VI) was tested by applying a synthetic stormwater runoff solution with a neutral pH and high Cr(VI) concentrations to four intact soil columns excavated from two roadside infiltration swales in Germany. Inlet flow rates mimicked normal (10 mm in 2 h) and extreme (100 mm in 3 h) rain events. The objectives were to understand the behaviour of the anionic and toxic Cr(VI) in soil at neutral pH and to asses treatment efficiency towards Cr(VI). During normal rain events Cr(VI) was largely retained (more than 50%), even though pH was neutral, while under extreme rain events approximately 20% of Cr(VI) was retained. In both cases effluent concentrations of Cr(VI) would exceed the threshold value of 3.4 μg/L if the infiltrated water were introduced to freshwater environments. More knowledge on the composition of the stormwater runoff, and especially the occurrence of Cr(VI), is needed.     

利用水化学方法识别岩溶水文系统中的径流

通过暴雨中的野外观测,确认了桂林丫吉试验场S31泉岩溶水文系统中多种径流形式：表层岩溶带管道流、回归流、坡面流和壤中流。现场测量发现不同形式径流的水化学特征(pH、电导率、Ca²⁺、HCO^-₃)存在差异,Ca²⁺的质量浓度相差最大可以达到3倍。从CaCO₃-H₂O-CO₂平衡体系来看,CO₂分压（p_CO2）对径流的水化学特征具有控制作用。在大气p_CO2影响下的岩溶水矿化度较低,而土壤空气p_CO2达到2.7%,是大气的近百倍,其影响的径流矿化度较高。鉴于大气中和土壤中p_CO2的显著差异,从水化学特征上将径流分为2类,并且认为它们构成了系统出口洪水的2个主要来源。在此基础上利用水化学方法计算出S31岩溶泉洪水时的径流构成。结果表明,在暴雨的情形,由大气p_CO2环境产生形成的岩溶水的比例占到泉水总量的70%,进一步证明了快速流在岩溶水中的重要作用。     

Distribution of stable isotopes in arid storms

 Temporal distributions of the isotopic composition in arid rain storms and in the associated runoff were investigated in a small arid rocky basin in Israel. Customized rain and runoff samplers provided sequential water samples hermetically sealed in high-density PVC bags. In several storms where the runoff was isotopically depleted, compared with the rainfall, the difference could not be explained by fractionation effects occurring during overland flow. A water-balance study relating the runoff discharge to rainfall over a rocky watershed showed that the entire discharge is produced by a very small segment (1–2 mm) of the rain storm. The major objective, therefore, was to provide quantitative relations between segments of rainfall (rain showers and rain spells) and runoff. The time distribution of the composition of stable isotopes (oxygen and hydrogen) was used to quantify the correlation between the rain spell's amount and the consequent runoff. The aim of this work was to (a) utilize the dynamic variations in the isotopic composition in rainfall and runoff and model the magnitude of surface-storage capacity associated with runoff processes of overland flow, and (b) characterize the isotopic composition of the percolating water with respect to the isotopic distribution in rainfall and runoff events. The conceptual model postulates an isotopic mixing of overland flow with water within the depression storage. A transport model was then formulated in order to estimate the physical watershed parameters that control the development of overland flow from a certain rainfall period. Part I (this paper) presents the results and the assessment of the relative depression storage obtained from oxygen-18 and deuterium analyses that lead to the physical and mathematical formulation of a double-component model of kinematic-wave flow and transport, which is presented in Part II (accompanying paper). Received, February 1997 · Revised, September 1997 · Accepted, September 1997     

Hydrological modeling of typhoon-induced extreme storm runoffs from Shihmen watershed to reservoir, Taiwan

Typhoon-induced extreme storm runoffs often cause flood hazards. In this study, a hydrological model (HEC-HMS) was applied to Shihmen watershed located in Taiwan. Three typhoon-induced storm events, with return period ranging from 1 to 90 years, were used in case studies to characterize storm runoff. With a 5-year storm for model calibration, model parameters were carefully calibrated through the comparison between model simulated and observed flows at a stream gage station. The calibrated model was then verified for a 90-year storm and a 1-year storm event. Results indicate that the calibrated and verified HEC-HMS hydrological model is capable of providing satisfactory predictions of the typhoon-induced extreme storm runoff to support reservoir operation and flood hazard mitigation. Based on model simulations, typhoon-induced water table increases for different initial water volumes at Shihmen Reservoir was derived by adding storm-runoff volume to the reservoir’s initial elevation-volume rating curve. Water tables above the top elevation of the dam in the reservoir indicate the need for immediate water releases to avoid the risk of overflow over the dam.     

土坡降雨入渗影响因子模拟实验

综合模拟实验土坡降雨入渗的各种常见影响因子,实验结果表明:土质对降雨入渗能力的影响明显,土中粘粒含量越高,颗粒越细微,粒间孔隙越小,吸、保水性能越强,开始入渗速度较快,在一定时间后入渗趋于平缓,浸润线前锋位置与雨水之间存在滞后现象;土体结构都对土体入渗能力产生较大影响,随着土体密实程度的增加,土体水力传导度减小,其水分入渗能力明显降低,开始入渗速度较快,在30min过后入渗趋于平缓;在临界含水量内,渗透系数与饱和度成反比;在正常温度范围内,对渗透影响不明显;坡度与累积入渗深度基本呈凸形曲线关系;随着植被覆盖度增加,累积入渗量成直线增加。     

Bayesian approach to daily rainfall modelling to estimate monthly net infiltration using the Thornthwaite water budget and Curve Number methods

The Thornthwaite and Mather water budget is a simple and frequently applicable tool to estimate surpluses of water, which are not stored in the soil profile. Combining it with the empiric CN-method of the US Soil Conservation Service (US-SCS), which is applied to daily rainfall records, it is possible to estimate the runoff, and this way, from the difference between surpluses and runoff, to estimate the net infiltration that would recharge a phreatic aquifer. In order to apply both methods during a sequence of years, it is necessary to predict the number of rain events per month, and the rainfall depth for each event. In this work, the author proposes a methodology based on the theorem of Bayes to estimate the number of occurrences of rainy events in a considered month conditioning the forecast to the monthly rainfall. In addition, an exponential distribution to generate rainfall depth knowing the monthly rainfall was done. Both algorithms were applied in four stations of the southern region of Santa Fe province (Argentina). More than 7,600 forecasts of rain occurrences and rainfall depths were compared with the observed records. Moreover, the runoff values estimated by means of the US-SCS method, using the observed rainfall and using rainfalls predicted with the algorithms were also compared. In both cases, the obtained results were also very satisfactory. The proposed methodologies allow the correct application of the balance of Thornthwaite and Mather together with the US-SCS method and a good forecast of monthly runoff and net infiltration.