Modified models for better prediction of infiltration rates in trapezoidal permeable stormwater channels     

《水文科学杂志》2012,57(15):1918-1931

ABSTRACT

In stormwater management, it is important to accurately quantify the infiltration rates to solve urban runoff-related problems. This study proposes a method to improve estimates of the infiltration rate in permeable stormwater channels. As part of the analysis, five infiltration models were evaluated: the Kostiakov, Horton, modified Kostiakov, Philip and SCS (Soil Conservation Service) models. Infiltration tests with various initial water levels were performed on channel models with differing base width and side slopes. The results show that the addition of three parameters that describe the trapezoidal cross-sectional area, i.e. the depth, side slope and base width, in the infiltration models yielded better estimates of the infiltration rate. A comparison of the infiltration capacity values obtained from the models after the three parameters were added with those that were experimentally obtained, shows that the improved modified Kostiakov model is the most suitable model to predict infiltration rates in trapezoidal permeable stormwater channels.  相似文献   

Mean and turbulent flow fields in a simulated ice‐covered channel with a gravel bed: some laboratory observations     

André Robert  Thang Tran 《地球表面变化过程与地形》2012,37(9):951-956

Northern rivers experience freeze‐up over the winter, creating asymmetric under‐ice flows. Field and laboratory measurements of under‐ice flows typically exhibit flow asymmetry and its characteristics depend on the presence of roughness elements on the ice cover underside. In this study, flume experiments of flows under a simulated ice cover are presented. Open water conditions and simulated rough ice‐covered flows are discussed. Mean flow and turbulent flow statistics were obtained from an Acoustic Doppler Velocimeter (ADV) above a gravel‐bed surface. A central region of faster flow develops in the middle portion of the flow with the addition of a rough cover. The turbulent flow characteristics are unambiguously different when simulated ice covered conditions are used. Two distinct boundary layers (near the bed and in the vicinity of the ice cover, near the water surface) are clearly identified, each being characterized by high turbulent intensity levels. Detailed profile measurements of Reynolds stresses and turbulent kinetic energy indicate that the turbulence structure is strongly influenced by the presence of an ice cover and its roughness characteristics. In general, for y/d > 0·4 (where y is height above bed and d is local flow depth), the addition of cover and its roughening tends to generate higher turbulent kinetic energy values in comparison to open water flows and Reynolds stresses become increasingly negative due to increased turbulence levels in the vicinity of the rough ice cover. The high negative Reynolds stresses not only indicate high turbulence levels created by the rough ice cover but also coherent flow structures where quadrants one and three dominate. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

福建晋江市前港湖、龙湖等四湖泊的成因机理   总被引：1，自引：0，他引：1       下载免费PDF全文

徐起浩  施建生 《地震地质》2012,34(1):110-128

对前港湖、龙湖、虺湖、(氵丙)州湖的地理环境进行了实地考察,对钻孔和钻孔岩心沉积相及微体古生物进行了分析,对14C样品进行了年代测定,特别是通过对龙湖湖内和沿岸共78个钻孔岩心的分析,揭示了龙湖及沿岸残坡积层和晚更新世以来的沉积层展布,进而得到了龙湖成湖前的凹陷和发育在凹陷内的古河流环境,最终推断这4个湖泊为全新世晚期地震断塞湖.主要理由是:这4个湖沿衙口-(氵丙)州隐伏断裂(控制深沪湾地堑NW侧边界的断裂)呈线状展布,都为淡水湖;都发育在晚更新统含砾砂黏土及残坡积层构成的凹陷内,成湖前凹陷内有古河流;已发现龙湖湖盆SE近隐伏断裂处的下游古河床被抬高,且高出上游河床3m以上;前港湖、龙湖的最早成湖年龄都为距今2.4ka左右,这个年龄处于全新世晚期的强古地震发生的可能时间区间内,该地震同时导致了深沪湾海底古森林更深沉没于海底;都存在湖坝和可能的地震沉积相.推断上述湖泊是在该古地震时衙口-(氵丙)州断裂NW侧地块翘起掀升堵塞河流形成的地震断塞湖.湖泊形成后,当地盛行的风沙在湖坝处的加积和在地堑内的填积,导致湖坝变宽增高并和地堑沉积连成大致等高的一体,阻挡了湖水的外流,这是使湖泊继续发育并留存至今的重要原因.  相似文献   

The correlation and sequence architecture of the Ormskirk Sandstone Formation in the Triassic Sherwood Sandstone Group of the East Irish Sea Basin,NW England     

N. S. Meadows 《Geological Journal》2006,41(1):93-122

The existing stratigraphic nomenclature applied to the Early and Middle Triassic Sherwood Sandstone Group in NW England has resulted from more than 150 years of geological investigation, but is characterized by a lithostratigraphic system that is insufficiently flexible to allow for variations in lithology and sedimentary facies within a continental depositional system. A revised well correlation based on the detrital mineralogical and chemical composition of the Ormskirk Sandstone Formation in four offshore wells, that is then extended to provide near‐basin‐wide well correlations using a regional shale marker, confirms previously suggested but unproven diachroneity at the top of the Sherwood Sandstone Group. It also reveals the presence of incised valleys filled by stacked amalgamated fluvial channel sandstones and cut into previously deposited aeolian and sandflat sequences as well as older fluvial channel sandstones. The combination of well correlations indicates that the valleys were incised by a fluvial system flowing NW from the Cheshire Basin into the East Irish Sea Basin and then west towards the Peel and Kish Bank basins. The stratal geometry of the upper part of the Sherwood Sandstone Group is suggested to conform to models of climatically mediated alternations of fluvial degradation and aggradation in response to changes in the relationship between sediment flux and stream discharge. This model is supported in the Sherwood Sandstone Group by climatically driven variations in the non‐channelized facies which record upward wetting and drying cycles that can be locally tied to fluvial incision surfaces, and suggest a hierarchy of at least three levels of climatic cyclicity recorded within the sedimentary succession. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Patch‐scale representation of vegetation within hydraulic models          下载免费PDF全文

Timothy I. Marjoribanks  Richard J. Hardy  Stuart N. Lane  Matthew J. Tancock 《地球表面变化过程与地形》2017,42(5):699-710

Submerged aquatic vegetation affects flow, sediment and ecological processes within rivers. Quantifying these effects is key to effective river management. Despite a wealth of research into vegetated flows, the detailed flow characteristics around real plants in natural channels are still poorly understood. Here we present a new methodology for representing vegetation patches within computational fluid dynamics (CFD) models of vegetated channels. Vegetation is represented using a Mass Flux Scaling Algorithm (MFSA) and drag term within the Reynolds‐averaged Navier–Stokes Equations, which account for the mass and momentum effects of the vegetation, respectively. The model is applied using three different grid resolutions (0.2, 0.1 and 0.05 m) using time‐averaged solution methods and compared to field data. The results show that the model reproduces the complex spatial flow heterogeneity within the channel and that increasing the resolution leads to enhanced model accuracy. Future applications of the model to the prediction of channel roughness, sedimentation and key eco‐hydraulic variables are presented, likely to be valuable for informing effective river management. © 2016 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

Width variations control the development of grain structuring in steep step-pool dominated streams: insight from flume experiments     

Matteo Saletti  Marwan A. Hassan 《地球表面变化过程与地形》2020,45(6):1430-1440

We report results from flume experiments designed to study the effect of width variations on the formation and stability of steps in steep streams. To physically model channel width changes we inserted multiple trapezoidal elements in the flume. Two competing effects are in play: a fluidic effect, suggesting that steps are more likely to form in wide areas because of deposition enhanced by lower shear stress, and a granular effect, suggesting that steps are more likely to form in narrow areas because of particle jamming. Our experiments show that width variations enhance the formation of steps. Although steps can form in every location, those in narrow/narrowing areas are more common, more stable and they occupy a larger portion of the channel width. These results stress the importance of particle interactions in coarse-bedded streams and help river engineers by providing a new element to consider when designing step-pool sequences in river restoration projects. © 2020 John Wiley & Sons, Ltd.  相似文献   

曲阜近山前地区地热地质条件浅析          下载免费PDF全文

胡玉禄  回寒星  胡红文  王克光  高赞东 《山东国土资源》2005,21(4):35-37

曲阜市近山前地区基底地层是理想的热介质,区域主控断裂对地温场起明显控制作用,含水岩组和地下水运动为地热提供了理想载体。以岩石导热特征,可将曲阜地区地层分为2 大类:即热基底地层和热盖层地层。前者热导率为25.41×10-3~36.30×10-3T/cm·s·℃;后者为18.92×10-3~23.99×10-3 T/cm·s·℃。地热资源赋存于受断裂构造控制的槽形地带内,属典型的构造—盆地增温型。  相似文献   

利用AIRS数据交叉辐射定标SVISSR分裂窗通道   总被引：1，自引：0，他引：1       下载免费PDF全文

蒋耿明  延昊  马灵玲 《遥感学报》2009,13(5):797-807

利用高精度和稳定的AIRS/Aqua(Atmospheric InfraRed Sounder on board Aqua)数据对SVISSR/FY- 2C(Stretched Visible and Infrared Spin Scan Radiometer onboard FengYun 2C)的两个分裂窗通道IR1(InfraRed 1, 10.9 μm)和IR2(InfraRed 2, 11.9μm)进行交叉辐射定标的方法, 并利用赤道附近2006年12月和2007年12月的AIRS和SVISSR数据完成了交叉辐射定标, 结果表明, SVISSR数据与卷积得到的AIRS数据高度线性相关, SVISSR/FY-2C传感器的两个分裂窗通道不仅存在定标误差, 而且定标误差随时间的变化呈现增大的趋势。相对于AIRS/Aqua测量值, 当SVISSR的通道亮温从220 K变化到340 K时, 2006年12月IR1通道的温度调整量从5.8 K变化到-4.4 K, 而2007年12月IR1通道的温度调整量从6.9 K变化到-5.1 K; 2006年12月IR2通道的温度调整量从2.2 K变化到-1.5 K, 而2007年12月IR2通道的温度调整量从6.3 K变化到-6.1 K。  相似文献