Performance of grass and eucalyptus riparian buffers in a pasture catchment,Western Australia,part 1: riparian hydrology     

Lucy A. McKergow  Ian P. Prosser  David M. Weaver  Rodger B. Grayson  Adrian E. Reed 《水文研究》2006,20(11):2309-2326

Rainfall takes many flowpaths to reach a stream, and the success of riparian buffers in water quality management is significantly influenced by riparian hydrology. This paper presents results from hydrometric monitoring of riparian buffer hydrology in a pasture catchment. Runoff processes and riparian flowpaths were investigated on two planar hillslopes with regenerating grass and E. globulus buffers. Surface runoff and subsurface flows (A‐ and B‐horizons) were measured for 3 years using surface runoff collectors, subsurface troughs and piezometers. Water volumes moving through the riparian buffers via the measured flowpaths were ranked B‐horizon ? surface runoff ≈ A‐horizon. Runoff volumes through the B‐horizon troughs were an order of magnitude greater than those recorded for the most productive surface runoff plots or the A‐horizon troughs. Subsurface runoff and saturation‐excess overland flow (SOF) were limited to the winter months, whereas infiltration‐excess overland flow (IEOF) can occur all year round during intense storms. Surface runoff was recorded on 33 occasions, mostly during winter (late May–early October), and total annual surface runoff volumes collected by the 20 unconfined (2 m wide) runoff plots varied between > 80 and < 20 m³. Subsurface flow only occurred in winter, and the 6 m wide B‐horizon subsurface troughs flowed above 1 l s^?1 continuously, whereas the A‐horizon troughs flowed infrequently (<6 days per year). In summer, surface runoff occurred as IEOF during intense storms in the E. globulus buffer, but not in the grass buffer. Observations suggest that surface crusting reduced the soil's infiltration capacity in the E. globulus buffer. During winter, SOF and seepage were observed in both buffers, but subsurface flow through the B‐horizon was the dominant flowpath. Key hydrologic differences between the grass and tree buffers are the generation of IEOF in the E. globulus buffer during intense summer storms, and the smaller subsurface runoff volumes and fewer flow days in the E. globulus buffer. Low surface runoff volumes are likely to limit the potential of these buffers to filter pollutants from surface runoff. High subsurface flow volumes and saturated conductivities are also likely to limit the residence time of water in the subsurface domain. Based on their hydrologic performance, the key roles of riparian buffers in this landscape are likely to be displacing sediment and nutrient‐generating activities away from streams and stabilizing channel morphology. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Performance of grass and eucalyptus riparian buffers in a pasture catchment,Western Australia,part 2: water quality     

Lucy A. McKergow  Ian P. Prosser  David M. Weaver  Rodger B. Grayson  Adrian E. G. Reed 《水文研究》2006,20(11):2327-2346

Declining water quality on the south coast of Western Australia has been linked to current agricultural practices. Riparian buffers were identified as a tool available to farmers and catchment managers to achieve water quality improvements. This study compares 10 m wide regenerating grass and Eucalyptus globulus buffer performance. Surface and subsurface water quality were monitored over a 3‐year period. Nutrient and sediment transport were both dominated by subsurface flow, in particular through the B‐horizon, and this may seriously limit the surface‐runoff‐related functions of the riparian buffers. Riparian buffer trapping efficiencies were variable on an event basis and annual basis. The grass buffer reduced total phosphorus, filterable reactive phosphorus, total nitrogen and suspended sediment loads from surface runoff by 50 to 60%. The E. globulus buffer was not as effective, and total load reductions in surface runoff ranged between 10 and 40%. A key difference between the grass and E. globulus buffers was the seasonality of sediment and nutrient transport. Surface runoff, and therefore sediment and nutrient transport, occurred throughout the year in the E. globulus buffer, but only during the winter in the grass buffer. As a consequence of high summer nutrient and sediment concentrations, half the annual loads moving via surface runoff pathways through the E. globulus buffer were transported during intense summer storms. This study demonstrates that grass and E. globulus riparian buffers receiving runoff from pasture under natural rainfall can reduce sediment and nutrient loads from surface runoff. However, in this environment the B‐horizon subsurface flow is the dominant flowpath for nutrient transport through the riparian buffers, and this subsurface flow pathway carries contaminant loads at least three times greater than surface runoff. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Woody buffer effects on water temperature: The role of spatial configuration and daily temperature fluctuations     

Jochem Kail  Martin Palt  Armin Lorenz  Daniel Hering 《水文研究》2021,35(1):e14008

Water temperature is a key driver for riverine biota and strongly depends on shading by woody riparian vegetation in summer. While the general effects of shading on daily maximum water temperature T_max are well understood, knowledge gaps on the role of the spatial configuration still exist. In this study, the effect of riparian buffer length, width, and canopy cover (percentage of buffer area covered by woody vegetation) on T_max was investigated during summer baseflow using data measured in seven small lowland streams in western Germany (wetted width 0.8–3.7 m). The effect of buffer length on T_max differed between downstream cooling and heating: T_max approached cooler equilibrium conditions after a distance of 0.4 km (~45 min travel-time) downstream of a sharp increase in canopy cover. In contrast, T_max continued to rise downstream of a sharp decrease in canopy cover along the whole 1.6 km stream length investigated. The effect of woody vegetation on T_max depended on buffer width, with changes in canopy cover in a 10 m wide buffer being a better predictor for changes in T_max compared to a 30 m buffer. The effect of woody vegetation on T_max was linearly related to canopy cover but also depended on daily temperature range T_range, which itself was governed by cloudiness, upstream canopy cover, and season. The derived empirical relationship indicated that T_max was reduced by −4.6°C and increased by +2.7°C downstream of a change from unshaded to fully shaded conditions and vice versa. This maximum effect was predicted for a 10 m wide buffer at sunny days in early summer, in streams with large diel fluctuations (large T_range). Therefore, even narrow woody riparian buffers may substantially reduce the increase in T_max due to climate change, especially in small shallow headwater streams with low baseflow discharge and large daily temperature fluctuations.  相似文献   

电扰动仪数据处理软件的设计和实现     

王军  方召盟  何案华  高亮 《震灾防御技术》2016,11(3):667-673

使用Visual C++开发适用于高采样率电扰动仪的数据处理软件,可以对数据进行快速绘图、交互式预处理和初步分析,并具备简单的仪器运行统计功能,极大地提高了预处理和数据分析的效率。  相似文献   

基于3S技术的城市辐射效应景观分析——以蓬莱市为例     

蔡明玉  常学礼  张继平  李健英 《测绘科学》2008,33(3):38-40

本文在3S技术的支持下采用缓冲区分析,从景观和斑块两个层次对蓬莱市城市辐射效应与景观结构关系进行了研究。结果表明:在景观层次上,随着城市辐射距离的增加,景观破碎化降低。在斑块层次上,蓬莱市的城市辐射效应对果园和水浇地的影响较大,最大距离是25km;对其他斑块类型影响不大。这表明山东半岛城市化进程加剧了景观的破碎化,而且这一过程主要是通过影响果园和水浇地斑块来实现的。  相似文献   

平面P波入射下深埋圆形复合式衬砌隧道抗减震机理研究          下载免费PDF全文

王帅帅  高波 《地震工程学报》2016,38(2):159-165

基于Fourier-Bessel级数展开法,研究深埋圆形三层复合式衬砌洞室在平面P波入射下的动应力集中问题,并给出三层衬砌洞室动应力集中系数级数解析解;依托某IX度地震区管道隧道实际工程,分析不同衬砌刚度组合和厚度组合对洞室动应力集中系数的影响。研究表明:注浆加固洞室围岩和设置减震层都可以降低二次衬砌动应力集中系数;增大围岩注浆区弹性模量和厚度,有利于减小衬砌动应力集中系数,最优围岩注浆区厚度为1倍洞室净空半径;减震层弹性模量降低,减震层厚度增大,二次衬砌动应力集中系数变小,减震层弹性模量宜低于围岩弹模1/20,最优减震层厚度宜取1/50的洞室内净空半径。最后针对实际管道隧道抗减震技术,考虑围岩稳定性,提出"围岩-加固圈-减震层-衬砌"新型减震结构,分析结果表明:对比其他三种抗减震措施,新型减震结构的减震效果最好。  相似文献   

GIS支持下银川盆地地震与活动断裂关系研究   总被引：1，自引：0，他引：1  

崔瑾 《地震研究》2014,37(3)

在建立了银川盆地活动断裂和地震资料数据库的基础上,利用缓冲区分析、叠加分析和统计分析等方法,进行GIS支持下的地震与活动断裂关系的研究,探明了以20 km为半径的缓冲区内包含了约95%的地震,区内的近代地震主要沿全新世活动断裂分布,正断裂的单位地震数较高,在断裂交汇区地震分布较集中。研究结果表明,GIS技术是地震与活动断裂关系研究的有效手段。  相似文献   

基于条带扫描思想的线目标缓冲区快速构建   总被引：11，自引：0，他引：11  

朱熀  艾廷华  王洪 《测绘学报》2006,35(2):171-176

空间目标缓冲区建立的传统算法是基于平行双线扩展思想,在基线复杂分布情形下,该算法对于岛屿和多边形外环的构建及空间关系的处理十分困难。将计算几何的旨在提高运算速度的“条带扫描”思想引入到缓冲区建立过程,对曲线分离出多个两点连接的线段集,生成每条线段的椭圆形基元缓冲区,通过条带扫描法对基元缓冲区叠置生成岛屿内环与多边形外环,判断其间的套合关系。该算法在严密的逻辑组合分析条件下能够对单条或多条基线的复杂情形生成正确的缓冲区多边形,同时运算速度得到改进,达到O(nlogn)。  相似文献   

新型变权弱化缓冲算子的构造     

顾红  姚天祥 《南京气象学院学报》2012,4(3):279-284

根据灰色系统理论中的新信息优先利用原则,在灰色系统缓冲算子三公理体系下构造了新型变权弱化缓冲算子,研究了缓冲算子调节度与可变权重之间的关系.变权缓冲算子有效解决了由于传统缓冲算子不能实现作用强度的微调而导致的缓冲作用效果过强或过弱的问题.最后,通过实例说明了变权缓冲算子在控制作用强度方面的灵活性.  相似文献   

MapGIS K9 IMS缓冲区分析二次开发的研究与应用     

郝明  张建龙  邓昌荣  梁虹 《地理空间信息》2012,10(6):22-25,5

MapGIS K9 IMS平台底层依托超大型的地理信息系统平台MapGIS K9,且融入了互联网的各种技术,是一个功能全面、简便易用、特点突出、性能稳定的互联网地理信息系统开发平台。在该平台基础上,结合"青藏高原基础地质数据库管理系统"项目的功能需要,详细介绍了缓冲区分析二次开发的流程与经验,并且在该系统中得到了很好的应用。  相似文献