Effects of rainfall intensity fluctuations on infiltration and runoff: rainfall simulation on dryland soils,Fowlers Gap,Australia   总被引：4，自引：0，他引：4  

David Dunkerley 《水文研究》2012,26(15):2211-2224

Small plots and a dripper rainfall simulator were used to explore the significance of the intensity fluctuations (‘event profile’) within simulated rainfall events on infiltration and runoff from bare, crusted dryland soils. Rainfall was applied at mean rain rates of 10 mm/h. Fourteen simulated rainfall events each involved more than 5000 changes of intensity and included multipeak events with a 25‐mm/h peak of intensity early in the event or late in the event and an event that included a temporary cessation of rain. These are all event profiles commonly seen in natural rain but rarely addressed in rainfall simulation. A rectangular event profile of constant intensity, as commonly used in rainfall simulation experiments, was also adopted for comparative purposes. Results demonstrate that event profile exerts an important effect on infiltration and runoff for these soils and rainfall event profiles. ‘Uniform’ events of unvarying intensity yielded the lowest total runoff, the lowest peak runoff rate and the lowest runoff ratio (0.13). These parameters increased for ‘early peak’ profiles (runoff ratio 0.24) and reached maxima for ‘late peak’ profiles (runoff ratio 0.50). Differences in runoff ratio and peak runoff rate between the ‘uniform’ event profile and those of varying intensity were all statistically significant at p ≤ 0.01. Compared with ‘uniform’ runs, the varying intensity runs yielded larger runoff ratios and peak runoff rates, exceeding those of the ‘uniform’ events by 85%–570%. These results suggest that for small‐plot studies of infiltration and erosion, the continued use of constant rainfall intensity simulations may be sacrificing important information and misrepresenting the mechanisms involved in runoff generation. The implications of these findings for the ecohydrology of the research site, an area of contour‐aligned banded vegetation in which runoff and runon are of critical importance, are highlighted. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Compared performance of a conceptual and a mechanistic hydrologic models of a green roof   总被引：1，自引：0，他引：1  

A. Palla  I. Gnecco  L. G. Lanza 《水文研究》2012,26(1):73-84

In order to investigate the hydrologic response of a green roof system within the urban environment, a monitoring campaign is carried out at the green roof site of the University of Genova (Italy). Experimental data confirm that the green roof is able to significantly mitigate the generation of runoff with median values of retained volume and peak reduction, respectively, equal to 94 and 98%. A conceptual linear reservoir and a simple mechanistic (Hydrus‐1D) models are implemented to simulate the hydrologic behaviour of the system; each model is calibrated and validated based on experimental data collected at the green roof site. The hydrographs simulated with both hydrologic models reproduce with acceptable matching capabilities the experimental measurements, as confirmed by the Nash‐Sutcliffe Efficiency index generally greater than 0·60. Although the relative percentage differences evaluated for the selected hydrograph variables (the total effluent volume, the peak flow rate and the hydrograph centroid) demonstrate that the mechanistic model is more accurate, prediction errors of the conceptual model are generally limited when compared with the observed hydrologic performance. Results of the present comparison are useful in supporting conceptual model selection in case the hydrologic response is addressed for hydrologic performance assessment. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

一种用于突发性场地污染模拟的解析模型     

陈家军  王浩  全向春  文军 《地球科学与环境学报》2012,(1):72-78,95

为了及时有效地应对各种突发性环境污染事故,有必要开发一种简单实用、适于各类型污染物的场地污染数学模型。通过污染事故发生后污染物在包气带、饱和带迁移转化的概化,建立了污染物运移的自由入渗模型以及降雨入渗模型并给出各自相应的解析解。无降雨时,考虑污染物在重力作用下随包气带向下渗透的作用,建立一维垂直入渗模型。有降雨时,考虑污染场地(包气带)中污染物迁移和转化的对流作用、扩散作用及挥发、生物降解、吸附、根系吸收等作用,建立包气带剖面二维溶质运移模型和饱和带平面二维溶质运移数学模型。建模过程中,假定降雨量的平均分布及土壤质地、水力参数以及有机物成分、种类均相同,同时假定污染物与多孔介质间的作用为线性吸附,植物根系对污染物的吸附遵循一级动力学。基于模型的解析解,实现案例的模拟计算。模拟结果表明:该模型具有适用范围广、模拟高效快捷等优点,能够较准确预测污染发生后污染物在土壤中的动向、到达饱和带的时间以及饱和带中污染物的迁移情况。  相似文献   

太湖疏浚底泥堆场黏土防渗层阻隔污染物的试验研究   总被引：1，自引：0，他引：1  

李涛  张志红  唐保荣 《岩土力学》2012,33(4):993-998

底泥疏浚是治理太湖污染的必要途径之一。限于目前国内的经济与技术条件以及疏浚底泥的数量巨大,太湖雪浪底泥堆场只能直接采用下部的天然黏性土层作为防渗层而不加任何处理。为了确保疏浚污染底泥在堆放期间不对周围环境和地下水造成污染,采用渗透与阻隔、静态吸附、动态土柱等试验测定和分析了黏土层对底泥中主要污染物（总氮、氨氮、硝氮、亚硝氮、总磷、化学耗氧量（COD））渗透和运移的阻隔能力,同时得到了可用于分析污染物在土层中运移和转化规律的一些重要参数。试验结果表明,雪浪堆场下部的黏土层对疏浚底泥中的主要污染物具有较强的吸附和阻隔能力。  相似文献   

溶井微污染水供水就地处理技术研究   总被引：1，自引：0，他引：1  

邹胜章  朱丹尼  李录娟  卢海平  周长松 《中国岩溶》2015,34(4):309-313

溶井是西南岩溶区主要的分散式供水方式。本文在对典型地区溶井水污染特征分析基础上,通过对现有分散供水水处理工艺原理的分析,提出了溶井供水的水污染防治措施,并结合中试试验,对溶井快渗池的设计思路、设计参数、水处理工艺以及施工中的注意事项进行了详细说明。试验表明,溶井在采取水处理措施后,出水浊度均低于5度,微量有机物去除率大于35%,氨氮可削减60%以上,细菌总数最大可截留95%;溶井快渗池工艺在溶井水处理过程中不需要添加任何药剂,避免了混凝剂和消毒剂对水质产生的副作用和卫生问题,出水水质主要指标基本达到生活饮用水卫生标准。   相似文献   

Uncertainty of rainfall-induced landslides considering spatial variability of parameters     

《Computers and Geotechnics》2017

A cross-correlation analysis is conducted to determine the impacts of the heterogeneity of hydraulic conductivity K_s, soil cohesion c′ and soil friction angle (tan φ′) on the uncertainty of slope stability in time and space during rainfall. We find the relative importance of tan φ′ and c′ depends on the effective stress. While the sensitivity of the stability to the variability of K_s is small, the large coefficient of variation of K_s may exacerbate the variability of pore-water pressure. Therefore, characterizing the heterogeneity of hydraulic properties and pore-water distribution in the field is critical to the stability analysis.  相似文献   

青藏高原多年冻土区高寒草甸土壤水分入渗变化研究   总被引：4，自引：3，他引：1  

朱美壮  王根绪  肖瑶  胡兆永  宋春林  黄克威 《冰川冻土》2017,39(6):1316-1325

在多年冻土区典型坡面上,将坡面划分为坡下（L）、坡中（M）和坡顶（H）三个坡位,每个坡位上各选取92%、60%和30%植被盖度为研究对象,用双环入渗仪测定土壤水分入渗过程,对影响土壤入渗过程的环境因子进行了分析,并基于土壤物理特性及土壤水分的测定进行模型模拟。结果表明：研究区不同植被盖度下土壤水分入渗性能在活动层冻融过程中差异明显,初始含水量和初始入渗率具有较好的负相关关系;稳定入渗率大小为：活动层融化期,92%（0.61 mm·min^-1） > 60%（0.50 mm·min^-1） > 30%（0.29 mm·min^-1）;活动层开始冻结期,60%（0.56 mm·min^-1） > 30%（0.39 mm·min^-1） > 92%（0.26 mm·min^-1）。土壤水分入渗速率具有显著的坡位差异并与冻土的冻融循环过程关系紧密。主要表现为,稳定入渗速率随坡位高度的降低依次递减;同一坡位下,开始冻结期入渗速率小于融化期。在整个入渗阶段,坡顶的累积入渗量是最大的,体现了较好的入渗性能。影响高寒草甸土壤水分入渗的环境因子主要有容重,有机质含量及粒径<0.1 mm微粒。通过比较研究得出,在长江源地区,活动层融化期通用经验模型f（t）=a+bt^-n更适用于该研究区域高寒草甸土壤水分入渗过程的研究,而在开始冻结期Horton模型f（t）=i_c+（i₀-i_c）e^-kt则具有更好的适用性。  相似文献   

地表水入渗对垃圾填埋场水质水量影响的数值模拟分析   总被引：3，自引：0，他引：3  

赵颖  梁冰  薛强  刘磊 《岩土力学》2010,31(7):2295-2302

将填埋垃圾视作一种特殊土体,建立了综合描述垃圾填埋场内渗滤液水分的饱和-非饱和渗流、垃圾土体沉降变形、有机污染物的释放、迁移、转化,以及微生物的生长、衰减等物理化学过程的多场耦合仿真分析模型,将任意的Lagrangian- Eulerian（ALE）方法引入到模型求解中,基于自行开发的仿真分析程序,开展了地表水入渗对垃圾填埋场水质、水量影响的数值仿真分析研究。模拟结果表明：300 d的非饱和水分入渗及内源水产生可使填埋单元内渗滤液饱和液面最高达6 m;地表水入渗对水相可溶性可降解有机物浓度和厌氧微生物浓度具有显著的影响,并间接地影响固相可溶性可降解有机物和微生物的浓度分布。  相似文献   

Modelling infiltration enhancement in a tropical urban catchment for improved stormwater management   总被引：1，自引：0，他引：1       下载免费PDF全文

Ting Fong May Chui  Dieu Huong Trinh 《水文研究》2016,30(23):4405-4419

To mitigate the impacts of impervious surfaces in urban areas, structures such as bioretention systems and permeable pavements have been installed to enhance infiltration in many countries. However, relatively little knowledge is available regarding the performance of such infiltration‐based structures in humid tropical and highly urbanized areas. This study investigates the feasibility of enhancing the infiltration of stormwater in tropical urbanized areas using Singapore as a case study. It first shows that the rainfall depth and intensity are both high, but the time interval between consecutive rainfall event is long in Singapore. It then numerically simulates single‐event local infiltration and finds that the fraction of infiltrated rainfall is actually high. It finally performs catchment‐scale simulations and finds that bioretention systems can enhance infiltration and groundwater recharge particularly during wet periods. However, local mounding of groundwater can be significant and can hinder the performance of those structures. Furthermore, with 5% of catchment area being converted to such structures, the infiltration of the entire catchment is enhanced but still not yet up to the natural level. To increase the overall effectiveness, future studies can look into bioretention systems with underdrain systems. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

降雨条件下考虑饱和渗透系数变异性的边坡可靠度分析   总被引：1，自引：0，他引：1  

豆红强  韩同春  龚晓南  李智宁  邱子义 《岩土力学》2016,37(4):1144-1152

土体饱和渗透系数表现为天然的变异性,为此基于Green-Ampt模型建立了考虑饱和渗透系数变异性的降雨入渗物理模型,并藉此模型确定了坡体湿润锋深度和含水率分布。然后结合无限长非饱和土边坡稳定模型得到解析形式的反映边坡稳定性的极限状态函数。采用Monte Carlo法对饱和渗透系数进行随机抽样并最终建立降雨条件下考虑饱和渗透系数变异性的边坡概率分析框架。针对一假想边坡,探讨了饱和渗透系数的变异系数、降雨持时和降雨强度对边坡破坏概率以及破坏发生时间概率分布的影响,结果表明：在降雨初期,边坡的破坏概率随饱和渗透系数变异性的增强而逐渐增加,但随着降雨的持续,破坏概率开始随变异性的增强而显著降低;滑坡最可能发生时间的大小并不受饱和渗透系数变异性的影响,而是直接取决于降雨强度;滑坡最可能发生时间所对应的概率却随变异性的增强而逐渐减小。  相似文献