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1.
Compared performance of a conceptual and a mechanistic hydrologic models of a green roof 总被引：1，自引：0，他引：1
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
2.
Abolfazl Rezaei Mohammad Zare Ezzatollah Raeisi Reza Namdar Ghanbari 《Ground water》2013,51(2):305-312
Kaftar Lake is a high‐altitude fresh water lake located in High Zagros, south of Iran. Despite the high annual evaporation to precipitation ratio in the area, lake water electrical conductivity is usually lower than 1000 µS/cm, this may be due to high seepage from the floor of the lake. Therefore, the hypothesis of possible underground connections between Namdan Basin, where the lake is located, and the surrounding basins with lower elevation (Aspas and Dehbid Basins) was investigated. Hydrogeology, hydrochemistry, and stable isotopes data of the lake and surrounding basins along with the lake water balance study were applied to test the hypothesis. Results indicate that Kaftar Lake has no connection with Aspas Basin in south, but it is hydraulically connected to Dehbid Basin. In Dehbid Basin, “Ghasr_e_Yaghoob spring” (average discharge ?1200 L/s) emerges from a small outcrop (about 0.8 km2) of Daryan limestone Formation, where this outcrop is much smaller than the required recharge area for such average discharge rate. The study shows that this spring is recharged by Kaftar Lake and Namdan Basin aquifer, through Daryan Formation of Gandboee Syncline located to the northern part of the lake. 相似文献
3.
Determination of the drainage structure of a watershed using a digital elevation model and a digital river and lake network 总被引：36，自引：0，他引：36
R. Turcotte J. -P. Fortin A. N. Rousseau S. Massicotte J. -P. Villeneuve 《Journal of Hydrology》2001,240(3-4):225-242
Distributed hydrological models require a detailed definition of a watershed's internal drainage structure. The conventional approach to obtain this drainage structure is to use an eight flow direction matrix (D8) which is derived from a raster digital elevation model (DEM). However, this approach leads to a rather coarse drainage structure when monitoring or gauging stations need to be accurately located within a watershed. This is largely due to limitations of the D8 approach and the lack of information over flat areas and pits. The D8 approach alone is also unable to differentiate lakes from plain areas.
To avoid these problems a new approach, using a digital river and lake network (DRLN) as input in addition to the DEM, has been developed. This new approach allows for an accurate fit between the DRLN and the modelled drainage structure, which is represented by a flow direction matrix and a modelled watercourse network. More importantly, the identification of lakes within the modelled network is now possible. The proposed approach, which is largely rooted in the D8 approach, uses the DRLN to correct modelled flow directions and network calculations. For DEM cells overlapped by the DRLN, flow directions are determined using DRLN connections only. The flow directions of the other DEM cells are evaluated with the D8 approach which uses a DEM that has been modified as a function of distance to the DRLN.
The proposed approach has been tested on the Chaudière River watershed in southern Québec, Canada. The modelled watershed drainage structure showed a high level of coherence with the DRLN. A comparison between the results obtained with the D8 approach and those obtained by the proposed approach clearly demonstrated an improvement over the conventionally modelled drainage structure. The proposed approach will benefit hydrological models which require data such as a flow direction matrix, a river and lake network and sub-watersheds for drainage structure information. 相似文献
4.
Shogo Kozaki 《Pure and Applied Geophysics》1976,114(6):879-889
Fields due to an electric current source in the atmosphere where the conductivity increases exponentially with altitude have been calculated. Characteristics of the field are described. The current source is assumednot to vary with time.Department of Electronic Engineering, Gumma University. 相似文献
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One of the aims of sewer networks is the protection of population against floods and the reduction of pollution rejected to the receiving water during rainy events. To meet these goals, managers have to equip the sewer networks with and to set up real-time control systems. Unfortunately, a component fault (leading to intolerable behaviour of the system) or sensor fault (deteriorating the process view and disturbing the local automatism) makes the sewer network supervision delicate. In order to ensure an adequate flow management during rainy events it is essential to set up procedures capable of detecting and diagnosing these anomalies.
This article introduces a real-time fault detection method, applicable to sewer networks, for the follow-up of rainy events. This method consists in comparing the sensor response with a forecast of this response. This forecast is provided by a model and more precisely by a state estimator: a Kalman filter. This Kalman filter provides not only a flow estimate but also an entity called ‘innovation’. In order to detect abnormal operations within the network, this innovation is analysed with the binary sequential probability ratio test of Wald. Moreover, by crossing available information on several nodes of the network, a diagnosis of the detected anomalies is carried out. This method provided encouraging results during the analysis of several rains, on the sewer network of Seine-Saint-Denis County, France. 相似文献
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Comparison of flowpaths to a well and spring in a karst aquifer 总被引：3，自引：0，他引：3
The permeability of some karst aquifers consists of networks of poorly integrated conduits and dissolution-widened fractures. The flow includes conduit flow, especially during storm recharge, but lacks the focused recharge into single master conduits that occurs in more highly developed karst systems. The proportions of conduit and dispersed flow are difficult to quantify in such systems. This study examines the flowpaths in a small karst watershed, based on comparing the physical and chemical response to storm flow at both a spring and a well. By conducting continuous monitoring at both locations, a better understanding of the flowpaths in a poorly integrated network was obtained. A more permeable flowpath to the spring leads to faster storm response and lower ion concentrations. The flowpath to and from the well is more complicated. The higher ion content and slower storm response suggest slower, more dispersed flowpaths. However, the well has greater variation in ion chemistry. Periodic recharge may dilute well concentrations due to faster (conduit or fracture) flowpaths. Although karst systems such as this are difficult to characterize, applying a variety of geochemical and physical monitoring techniques at multiple locations illustrates that the flowpaths can vary in both space and time. 相似文献
9.
This paper analyses measured data from two small tropical watersheds: one in a semiarid (Aiuaba, Brazil, 12·0 km2, 5 years of measurements) and another in a humid environment (Jaruco, Cuba, 43·5 km2, 21 years of measurements). The watersheds are similar with respect to catchment area (tens of km2), potential evaporation (2·1–2·6 m year?1), temperature (22–30 °C) and relief (mild hillslope steepness); but show considerable hydrological discrepancies: average precipitation in the humid watershed is two times higher; average river discharge (mm year?1) is five times higher; and surface water availability (mm year?1) is 14 times higher than in the semiarid watershed. Long‐term operation of hypothetical surface reservoirs in both basins is simulated. The analysis shows that 73% of the average river discharge are available (with 90% annual reliability) in the humid watershed, against only 28% in the semiarid. The main cause of this difference is the excess evaporation, which consumes 55% of the stored water in the semiarid reservoir, but only 12% in the humid one. The research concludes that: (1) although precipitation indicators are higher in the humid area, they are of the same order of magnitude as in the semiarid; and (2) fluvial‐regime and water‐availability variables are more than one order of magnitude higher in the humid basin, which shows a multiplication effect of these hydrological processes. Such major hydrological differences, despite the similarities between the two tropical watersheds, show the importance of further investigations in the field of comparative hydrology. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
B. Yadava 《Pure and Applied Geophysics》1970,78(1):78-85
Summary The transform calculus has been applied to investigate the disturbances in a composite piezoelectric media traversed by a magnetic field. 相似文献
11.
This paper considers the response of a beam with a dynamic vibration absorber, which consists of a viscoelastic solid and a double-cantilever viscoelastic beam, attached to the centre of the main beam. The ends of the main beam are built in and excited sinusoidally by the base motion. The transfer matrix method is used in the analysis. The displacement transmissibility, i.e. the ratio of the displacement at the centre of the main beam to that of the base is investigated in the numerical example. It is shown that the present absorber is effective to suppress several resonances of the main beam simultaneously by only one compact device. Values of the optimum tuning design parameters are presented in the numerical example. 相似文献
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N.H.C. Sparks S. Mann D.A. Bazylinski D.R. Lovley H.W. Jannasch R.B. Frankel 《Earth and Planetary Science Letters》1990,98(1)
Intracellular crystals of magnetite synthesized by cells of the magnetotactic vibroid organism, MV-1, and extracellular crystals of magnetite produced by the non-magnetotactic dissimilatory iron-reducing bacterium strain GS-15, were examined using high-resolution transmission electron microscopy, electron diffraction and57Fe Mo¨ssbauer spectroscopy. The magnetotactic bacterium contained a single chain of approximately 10 crystals aligned along the long axis of the cell. The crystals were essentially pure stoichiometric magnetite. When viewed along the crystal long axis the particles had a hexagonal cross-section whereas side-on they appeared as rectangules or truncated rectangles of average dimension, 53 × 35 nm. These findings are explained in terms of a three-dimensional morphology comprising a hexagonal prism of 110 faces which are capped and truncated by 111 end faces. Electron diffraction and lattice imaging studies indicated that the particles were structurally well-defined single crystals. In contrast, magnetite particles produced by the strain, GS-15 were irregular in shape and had smaller mean dimensions (14 nm). Single crystals were imaged but these were not of high structural perfection. These results highlight the influence of intracellular control on the crystallochemical specificity of bacterial magnetites. The characterization of these crystals is important in aiding the identification of biogenic magnetic materials in paleomagnetism and in studies of sediment magnetization. 相似文献
15.
Yanlin Zhang Guodong Cheng Xin Li Xujun Han Lei Wang Hongyi Li Xiaoli Chang G. N. Flerchinger 《水文研究》2013,27(25):3762-3776
Snow and frozen soil prevail in cold regions worldwide, and the integration of these processes is crucial in hydrological models. In this study, a combined model was developed by fully coupling a simultaneous heat and water model with a geomorphologically based distributed hydrological model. The combined model simulates vertical and lateral water transfer as well as vertical heat fluxes and is capable of representing the effects of frozen soil and snowmelt on hydrological processes in cold regions. This model was evaluated by using in situ observations in the Binggou watershed, an experimental watershed for cold region hydrology of the Watershed Allied Telemetry Experimental Research Project. Results showed that the model was able to predict soil freezing and thawing, unfrozen soil water content, and snow depth reasonably well. The simulated hydrograph was in good agreement with the in situ observation. The Nash–Sutcliffe coefficient of daily discharge was 0.744 for the entire simulation period, 0.472 from April to June, and 0.711 from June to November. This model can improve our understanding of hydrological processes in cold regions and assess the impacts of global warming on hydrological cycles and water resources. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
16.
利用InSAR(Interferometric SAR)干涉测量技术可以获得地表形变场(视线向, LOS), 将其与弹性半空间中一定断层模型模拟计算出的地表形变场进行正演分析, 以便获取发震断层的几何学和运动学参数, 是一种典型的前向模拟模式。 该计算模式由于模拟计算程序调试、 安装过程的复杂性, 使得在每台微机上安装此类程序不仅费时费力, 且浪费大量的计算资源。 文中首先介绍了实现InSAR干涉形变场模拟模型由单机推广到Internet/Intranet上进行远程计算最终建立“InSAR干涉形变场远程模拟系统”的过程, 并基于此系统平台对1997年玛尼MS7.9地震的InSAR地表形变场进行了模拟试算、分析等。 相似文献
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Maurizio Previati Davide Canone Edoardo Iurato Davide Gisolo Stefano Ferrari Pietro Teatini Mario Putti Stefano Ferraris 《水文研究》2020,34(5):1269-1284
A peat deposit (Zennare basin, Venice coastland, Italy) was monitored in previous field studies to investigate the hydrological response of organic soil to meteorological dynamics. Field tests and modelling predictions highlighted the risk of the complete loss of this peat layer during the next 50 years, due to oxidation enhanced by the increased frequency of warmer periods. Unfortunately, despite the considerable impacts that are expected to affect peat bogs (in this area and worldwide), only a few experimental studies have been carried out to assess the hydrologic response of peat to severe water scarcity. Because of that, an undisturbed 0.7 m3 peat monolith was collected, transferred to the laboratory and instrumented. The total weight (representative of the water content dynamics of the peat monolith as a whole), and two vertical profiles of matric potentials and water content were monitored in controlled water-scarce conditions. After an extended air-drying period, the monolith was used as an undisturbed peat lysimeter and a complete cycle of wetting and drainage was performed. Supplementary measurements of matric potential ψ and water content θ were collected by testing peat subsamples on a suction table apparatus. A set of water retention curves was determined in a range of matric potentials broader (ψ down to −7 m) than the current natural conditions in the field (minimum ψ = −1 m). While water content at saturation showed values similar to those in the original natural conditions (θ ≅ 0.8), a remarkable loss of water holding capacity (even for low potentials) has been highlighted, especially in deep layers that are now permanently below the water table. The retention curves changed shape and values, with a more pronounced hysteresis visible in an increasing distance between wetting and drying data. Hydraulic non-equilibrium between the water content and water potential could be a possible cause and it is worth modelling in future studies. The parameters of the van Genuchten retention curves were obtained for the wetting and the drying phases. 相似文献
19.
Suspension and calibration of a sediment trap 总被引：5，自引：0，他引：5
By Lars Håkanson 《Aquatic Sciences - Research Across Boundaries》1984,46(1):171-175
The aim of this technical note is to introduce a new, simple construction of a buoy-carried, suspended sediment trap that
meets given demands concerning design (geometry of vessels) and stability during the registration period. The device is based
on a ball-and-socket joint in the center and two Plexiglas cylinders (D=5cm, H=30cm) on PVC plastic arms. The suspension consists
of only three parts. To determine the optimal construction, the apparatus has been calibrated in a circulating flume at various
water velocities. 相似文献
20.
We discuss the form-drag instability for a quasi-geostrophic channel flow. We first study the characteristics of this instability in a barotropic flow, considering in detail the influence of the meridional scale and discussing which structure of the perturbation zonal flow must be chosen in order to describe properly this instability.We then consider a continuous quasi-geostrophic channel model in which the topography enters only through the bottom boundary condition, and we discuss how in this case the effects of the form-drag are felt by the mean zonal flow through the ageostrophic mean meridional circulation. Because the meridional structure of the perturbation zonal flow cannot simply be extended from the barotropic to the continuous case, we show how to modify it properly.We then study the baroclinic model in the particular case of constant (in the vertical) basic-state zonal flow and show how this case closely resembles the barotropic, demonstrating the barotropic nature of the form-drag instability.Symbols t
is the partial derivative with respect tot.
- x
is the partial derivative with respect tox.
- y
is the partial derivative with respect toy.
-
represents the geostrophic stream function.
-
u
is the eastward component of the geostrophic wind.
-
v
is the northward component of the geostrophic wind.
-
u
a
is the eastward component of the ageostrophic wind.
-
v
a
is the northward component of the ageostrophic wind.
-
w
is the vertical component of the wind.
-
f
is the Coriolis parameter=2 sin f
o+y.
-
f
o
is the Coriolis parameter evaluated at mid-latitude.
-
N
is the Brunt-Vaisala frequency.
- [A]
is the zonal (x) average ofA at constantp andy.
- <A>
is the horizontal (x andy) average ofA at constantp 相似文献