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1.
Diagnostic calibration and cross‐catchment transferability of a simple process‐consistent hydrologic model 
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下载免费PDF全文 The transferability of hydrologic models is of ever increasing importance for making improved hydrologic predictions and testing hypothesized hydrologic drivers. Here, we present an investigation into the variability and transferability of the recently introduced catchment connectivity model (Smith et al., 2013 ). The catchment connectivity model was developed following extensive experimental observations identifying the key drivers of streamflow in the Tenderfoot Creek Experimental Forest (Jencso et al., 2009 ; Jencso et al., 2010 ), with the goal of creating a simple model consistent with internal observations of catchment hydrologic connectivity patterns. The model was applied across seven catchments located within Tenderfoot Creek Experimental Forest to investigate spatial variability and transferability of model performance and parameterization. The results demonstrated that the model resulted in historically good fits (based on previous studies at the sites) to both the hydrograph and internal water table dynamics (corroborated with experimental observations). The impact of a priori parameter limits was also examined. It was observed that enforcing field‐based limits on model parameters resulted in slight reductions to streamflow hydrograph fits, but significant improvements to model process fidelity (as hydrologic connectivity), as well as moderate improvement in the transferability of model parameterizations from one catchment to the next. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
This study presents a Geographic Information System (GIS)‐based distributed rainfall‐runoff model for simulating surface flows in small to large watersheds during isolated storm events. The model takes into account the amount of interception storage to be filled using a modified Merriam ( 1960 ) approach before estimating infiltration by the Smith and Parlange ( 1978 ) method. The mechanics of overland and channel flow are modelled by the kinematic wave approximation of the Saint Venant equations which are then numerically solved by the weighted four‐point implicit finite difference method. In this modelling the watershed was discretized into overland planes and channels using the algorithms proposed by Garbrecht and Martz ( 1999 ). The model code was first validated by comparing the model output with an analytical solution for a hypothetical plane. Then the model was tested in a medium‐sized semi‐forested watershed of Pathri Rao located in the Shivalik ranges of the Garhwal Himalayas, India. Initially, a local sensitivity analysis was performed to identify the parameters to which the model outputs like runoff volume, peak flow and time to peak flow are sensitive. Before going for model validation, calibration was performed using the Ordered‐Physics‐based Parameter Adjustment (OPPA) method. The proposed Physically Based Distributed (PBD) model was then evaluated both at the watershed outlet as well as at the internal gauging station, making this study a first of its kind in Indian watersheds. The results of performance evaluation indicate that the model has simulated the runoff hydrographs reasonably well within the watershed as well as at the watershed outlet with the same set of calibrated parameters. The model also simulates, realistically, the temporal variation of the spatial distribution of runoff over the watershed and the same has been illustrated graphically. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
3.
Ray Kostaschuk Dan Shugar Jim Best Dan Parsons Stuart Lane Rich Hardy Oscar Orfeo 《地球表面变化过程与地形》2009,34(12):1605-1611
Field data from the Rio Paraná, Argentina, are used to examine patterns of suspended sediment transport over a sand dune. Measurements of three‐dimensional velocity are made with an acoustic Doppler current profiler whilst suspended sediment concentration and particle size have been quantified using a laser in situ sediment scattering transmissometer. Suspended sediment concentration and streamwise and vertical sediment flux are highest close to the bed, with an upward vertical flux over the stoss side of the dune and downward flux over the lee side. Suspended sediment concentrations are higher over the crest compared with the trough and suspended sediment is coarsest near the bed. About 17% of the suspended‐load transported over the crest is deposited in the lee side before it reaches the trough. Most of this deposited sand is coarser sediment that originates close to the bed over the crest, a result consistent with simulations based on the model of Mohrig and Smith (Water Resources Research 1996; 32: 3207–3217) for the excursion lengths of sediment dispersed in the lee side of a dune. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
4.
The presence of the metamorphic high-pressure/low-temperature mineral association of lawsonite-sodic amphibole is reported at Cape Smith on Smith Island, located in the southwestern end of the South Shetland Archipelago. This association confirms the existence of a high-pressure/low-temperature metamorphic belt along the Pacific margin of the Antarctic Peninsula. This belt is considered to be the meridional prolongation of the metamorphic belt of similar metamorphic conditions known along portions of the Pacific margin of South America. 相似文献
5.
ABSTRACTA three-dimensional flow and temperature model was applied for a 124 km river-reservoir system from Lewis Smith Dam tailrace to Bankhead Lock & Dam, Alabama. The model was calibrated against measured water levels, temperatures, velocities and flow rates from 4 May to 3 September 2011 under small constant release (2.83 m3/s) and large intermittent releases (~140 m3/s) from an upstream reservoir. Distributions of simulated flow and temperatures and particle tracking at various locations were analyzed which revealed the complex interactions of density currents, dynamic surface waves and solar heating. Flows in the surface and bottom layers moved in both upstream and downstream directions. If there was small constant release only from Smith Dam, simulated bottom temperatures at Cordova were on average 4.8°C higher than temperatures under actual releases. The momentum generated from large releases pushed bottom density currents downstream, but the released water took several days to reach Cordova.
Editor D. Koutsoyiannis; Associate editor B. Dewals 相似文献
6.
A sensitivity analysis of Hortonian flow 总被引：6，自引：0，他引：6
We present a sensitivity analysis for infiltration excess (Hortonian) overland flow based on a classic laboratory experiment by Smith and Woolhiser [Smith RE, Woolhiser DA. Overland flow on an infiltrating surface. Water Resour Res 1971;7(4):899–913]. The model components of the compartment approach are comprised of a diffusive wave approximation to the Saint–Venant equations for overland flow, a Richards model for flow in the variably saturated zone, and an interface coupling concept that combines the two components. In the coupling scheme a hydraulic interface is introduced to allow the definition of an exchange flux between the surface and the unsaturated zone. The effects of friction processes, soil capillarity, hydraulic interface, and vertical soil discretization on both infiltration and runoff prediction are investigated in detail. The corresponding sensitivity analysis is conducted using a small-perturbation method. As a result the importance of the hydraulic processes and related parameters are evaluated for the coupled hydrosystem. 相似文献
7.
ＣＴ机、ＳＰＥＣＴ及ＰＥＴ等医疗设备是当前重要的医疗诊断工具，但这些设备都跟某些射互有关，当放射性元素衰变而发射某种射线时，如果它们在４立体角范围内是等概率分布的，则扇形采集比在上方向上有集的效率提高了许多。 相似文献
8.
9.
D. J. Dupuis 《Journal of Hydrology》1997,200(1-4):295-306
In Smith (1986, J. Hydrol. 86, 27–43), a family of statistical distributions and estimators for extreme values based on a fixed number r > = 1 of the largest annual events are presented. The method of estimation was numerical maximum likelihood. In this paper, we consider the robust estimation of parameters in such families of distributions. The estimation technique, which is based on optimal B-robust estimates, will assign weights to each observation and give estimates of the parameters based on the data which are well modeled by the distribution. Thus, observations which are not consistent with the proposed distribution can be identified and the validity of the model can be assessed. The method is illustrated on Venice sea level data. 相似文献
10.
Andy Smith 《Astronomy& Geophysics》2000,41(3):3.32-3.33
A discussion meeting at Burlington House on 10 March 2000 featured eight speakers and an audience of about 50. Andy Smith reports. 相似文献
11.
A devastating pyroclastic surge and resultant lahars at Mount St. Helens on 18 May 1980 produced several catastrophic flowages into tributaries on the northeast volcano flank. The tributaries channeled the flows to Smith Creek valley, which lies within the area devastated by the surge but was unaffected by the great debris avalanche on the north flank. Stratigraphy shows that the pyroclastic surge preceded the lahars; there is no notable “wet” character to the surge deposits. Therefore the lahars must have originated as snowmelt, not as ejected water-saturated debris that segregated from the pyroclastic surge as has been inferred for other flanks of the volcano. In stratigraphic order the Smith Creek valley-floor materials comprise (1) a complex valley-bottom facies of the pyroclastic surge and a related pyroclastic flow, (2) an unusual hummocky diamict caused by complex mixing of lahars with the dry pyroclastic debris, and (3) deposits of secondary pyroclastic flows. These units are capped by silt containing accretionary lapilli, which began falling from a rapidly expanding mushroom-shaped cloud 20 minutes after the eruption's onset. The Smith Creek valley-bottom pyroclastic facies consists of (a) a weakly graded basal bed of fines-poor granular sand, the deposit of a low-concentration lithic pyroclastic surge, and (b) a bed of very poorly sorted pebble to cobble gravel inversely graded near its base, the deposit of a high-concentration lithic pyroclastic flow. The surge apparently segregated while crossing the steep headwater tributaries of Smith Creek; large fragments that settled from the turbulent surge formed a dense pyroclastic flow along the valley floor that lagged behind the front of the overland surge. The unusual hummocky diamict as thick as 15 m contains large lithic clasts supported by a tough, brown muddy sand matrix like that of lahar deposits upvalley. This unit contains irregular friable lenses and pods meters in diameter, blocks incorporated from the underlying dry and hot pyroclastic material that had been deposited only moments earlier. The hummocky unit is the deposit of a high-viscosity debris flow which formed when lahars mingled with the pyroclastic materials on Smith Creek valley floor. Overlying the debris flow are voluminous pyroclastic deposits of pebbly sand cut by fines-poor gas-escape pipes and containing charred wood. The deposits are thickest in topographic lows along margins of the hummocky diamict. Emplaced several minutes after the hot surge had passed, this is the deposit of numerous secondary pyroclastic flows derived from surge material deposited unstably on steep valley sides. 相似文献
12.
Prol-Ledesma Rosa Maria M. Gerardo Juarez 《Journal of Volcanology and Geothermal Research》1986,28(3-4)
Silica temperatures were calculated for 326 water samples from hot and warm springs located throughout Mexico as an attempt to estimate heat flow. Available heat flow data (Smith, 1974; Smith et al., 1979) for northern Mexico were related to silica temperature data to obtain the appropriate constants for the regional conditions according to Swanberg and Morgan's equation (1979, 1980). The constants obtained are similar to those obtained for the United States, therefore heat flow can be estimated on the basis of silica temperature data. By contouring calculated temperatures a map is obtained where the main geothermal provinces are shown. 相似文献
13.
This study examines the circulation and associated monthly-to-seasonal variability in the Caribbean Sea using a regional ocean
circulation model. The model domain covers the region between 99.0 and 54.0°W and between 8.0 and 30.3°N, with a horizontal
resolution of 1/6°. The ocean circulation model is driven by 6-hourly atmospheric reanalysis data from the National Center
for Environmental Prediction and boundary forcing extracted from 5-day global ocean reanalysis data produced by Smith et al.
(Mercator Newsletter 36:39–49, 2010), and integrated for 7 years. A comparison of model results with observations demonstrates that the regional ocean circulation
model has skill in simulating circulation and associated variability in the study region. Analysis of the model results, as
well as a companion model run that uses steady annual mean forcing, illustrates the role of Caribbean eddies for driving monthly-to-seasonal
circulation variability in the model. It is found that vertically integrated transport between Nicaragua and Jamaica is influenced
by the interaction between the density perturbations associated with Caribbean eddies and the Nicaraguan Ridge. The impact
of Caribbean eddies squeezing through the Yucatan Channel is also discussed. 相似文献
14.
A simple and fast determination of the limiting depth to the sources may represent a significant help to the data interpretation. To this end we explore the possibility of determining those source parameters shared by all the classes of models fitting the data. One approach is to determine the maximum depth-to-source compatible with the measured data, by using for example the well-known Bott–Smith rules. These rules involve only the knowledge of the field and its horizontal gradient maxima, and are independent from the density contrast.Thanks to the direct relationship between structural index and depth to sources we work out a simple and fast strategy to obtain the maximum depth by using the semi-automated methods, such as Euler deconvolution or depth-from-extreme-points method (DEXP).The proposed method consists in estimating the maximum depth as the one obtained for the highest allowable value of the structural index (Nmax). Nmax may be easily determined, since it depends only on the dimensionality of the problem (2D/3D) and on the nature of the analyzed field (e.g., gravity field or magnetic field). We tested our approach on synthetic models against the results obtained by the classical Bott–Smith formulas and the results are in fact very similar, confirming the validity of this method. However, while Bott–Smith formulas are restricted to the gravity field only, our method is applicable also to the magnetic field and to any derivative of the gravity and magnetic field. Our method yields a useful criterion to assess the source model based on the (∂f/∂x)max/fmax ratio.The usefulness of the method in real cases is demonstrated for a salt wall in the Mississippi basin, where the estimation of the maximum depth agrees with the seismic information. 相似文献
15.
G. V. Kotovich A. G. Kim S. Ya. Mikhailov V. P. Grozov Ya. S. Mikhailov 《Geomagnetism and Aeronomy》2006,46(4):517-521
A simple method for finding the critical frequency at a path midpoint from the distance-frequency characteristic measured on the one-hop path, based on the Smith method (the transmission curve method). The proposed method is the solution of the problem for the regular ionosphere along the path; therefore the method accuracy is also estimated as applied to irregular paths. The modeling results for the Khabarovsk-Irkutsk path are considered, and the experimental results for the Magadan-Irkutsk path are presented. 相似文献
16.
Time‐delay is an important issue in structural control. Applications of unsynchronized control forces due to time‐delay may result in a degradation of the control performance and it may even render the controlled structures to be unstable. In this paper, a state‐of‐the‐art review for available methods of time‐delay compensation is presented. Then, five methods for the compensation of fixed time‐delay are presented and investigated for active control of civil engineering structures. These include the recursive response method, state‐augmented compensation method, controllability based stabilization method, the Smith predictor method and the Pade approximation method, all are applicable to any control algorithm to be used for controlled design. Numerical simulations have been conducted for MDOF building models equipped with an active control system to demonstrate the stability and control performance of these time‐delay compensation methods. Finally, the stability and performance of the phase shift method, that is well‐known in civil engineering applications, have also been critically evaluated through numerical simulations. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
17.
Robert Smith 《Astronomy& Geophysics》2010,51(1):1.13-1.17
M eeting report Mike Edmunds and Robert Smith draw together the wide-ranging scientific contributions made by Bernard Pagel, the theme of an RAS Specialist Discussion Meeting on 13 and 14 November 2008. 相似文献
18.
Fourteen popular, representative infiltration models, some physically based, some semi‐empirical and some empirical, were selected for a comparative evaluation. Using the Nash and Sutcliffe efficiency criterion, the models were evaluated and compared for 243 sets of infiltration data collected from field and laboratory tests conducted in India and the USA on soils ranging from coarse sand to fine clay. Based on a relative grading scale, the semi‐empirical Singh–Yu general model, Holtan model and Horton model were graded respectively as 6·52, 5·57 and 5·48 out of 10. The empirical Huggins and Monke model, modified Kostiakov and Kostiakov model were graded as 5·57, 5·30 and 5·22, respectively. The physically based non‐linear and linear models of Smith–Parlange were graded as 5·48 and 5·22, respectively. Other models were ranked lower than these models. All the models generally performed poorly in field tests on Georgia's sandy soils, except the Robertsdale loamy sand. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
19.
The rainfall erosivity plays a fundamental role in water soil erosion processes and it can be expressed by its kinetic power. At first in this paper, the raindrop‐size distributions measured, in the period June 2006–March 2014, by an optical disdrometer installed at the Department of Agricultural and Forestry Sciences of University of Palermo are aggregated into rainfall intensity classes, having different ranges, and the measured kinetic power values are determined. Measured kinetic power values are initially used for testing the applicability of the kinetic power‐rainfall intensity relationships proposed by Wischmeier and Smith ( 1978 ), used in Universal Soil Loss Equation (USLE), Brown and Foster ( 1987 ) (RUSLE), and McGregor et al. ( 1995 ) (RUSLE2). Then, the reliability of a theoretical relationship for estimating the kinetic power by rainfall intensity and median volume diameter is verified. Finally, using the literature available datasets, corresponding to measurements carried out by different techniques and in different geographical sites, the analysis demonstrated that the rainfall intensity is not sufficient to determine the rainfall kinetic power. On the contrary, the theoretically deduced relationship allows to reproduce adequately the kinetic power of all available datasets, demonstrating that the knowledge of both rainfall intensity and median volume diameter allows a reliable estimate of the rainfall erosivity. 相似文献
20.
Peter Schröder, Robert Smith and Kevin Apps take a speculative look at what the future may hold as the Sun becomes a supergiant.
Astronomy textbooks tell us that one day the Sun will expand to become a red supergiant of enormous size, finally swallowing its inner planets, including Earth. However, recent solar evolution models, which account for a realistic amount of mass loss, suggest a (slightly) less catastrophic future for our planet. 相似文献
Astronomy textbooks tell us that one day the Sun will expand to become a red supergiant of enormous size, finally swallowing its inner planets, including Earth. However, recent solar evolution models, which account for a realistic amount of mass loss, suggest a (slightly) less catastrophic future for our planet. 相似文献