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1.
This study examined the influence of tidally‐induced oscillations of the beach water table in regulating beach surface moisture dynamics. A series of laboratory experiments were conducted to assess the influence of hysteresis and transient flow effects on surface moisture variability. The experimental apparatus utilized a column of well‐sorted fine sand partially immersed in a reservoir of water. The water level in the reservoir was raised and lowered via a diaphragm‐metering pump to simulate tidally induced fluctuations of the water table, and the moisture content profile within the column was monitored using an array of Delta‐T probes. Moisture contents at specific elevations within the column were utilized as proxies to represent various ‘surface’ elevations (relative to the high water table). Results indicate that surface moisture content behaves in a distinctly hysteretic manner. Examination of water flow scanning curves illustrated that for all surface elevations considered, higher moisture contents for a given pressure head occurred during the drying cycle than during the wetting cycle. This observation is particularly evident with shallow surface elevations (i.e. water table close to the surface) where the Haines Jump phenomenon was found to have a significant influence on moisture content dynamics. Additionally, an assessment of the accuracy of hysteretic and non‐hysteretic models to predict the measured moisture contents demonstrated that hysteretic simulations consistently provide a better representation of the observed moisture contents than non‐hysteretic simulations. A time lag was found between the respective maxima and minima in water table elevation surface moisture content. At the near surface water table positions the time lag ranged between 30 and 100 minutes, and it increased to 240 minutes (four hours) with the high water table at 60 cm below the surface. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

2.
A two‐dimensional (2D) finite‐difference shallow water model based on a second‐order hybrid type of total variation diminishing (TVD) approximate solver with a MUSCL limiter function was developed to model flooding and inundation problems where the evolution of the drying and wetting interface is numerically challenging. Both a minimum positive depth (MPD) scheme and a non‐MPD scheme were employed to handle the advancement of drying and wetting fronts. We used several model problems to verify the model, including a dam break in a slope channel, a dam break flooding over a triangular obstacle, an idealized circular dam‐break, and a tide flow over a mound. Computed results agreed well with the experiment data and other numerical results available. The model was then applied to simulate the dam breaking and flooding of Hsindien Creek, Taiwan, with the detailed river basin topography. Computed flooding scenarios show reasonable flow characteristics. Though the average speed of flooding is 6–7 m s?1, which corresponds to the subcritical flow condition (Fr < 1), the local maximum speed of flooding is 14·12 m s?1, which corresponds to the supercritical flow condition (Fr ≈ 1·31). It is necessary to conduct some kind of comparison of the numerical results with measurements/experiments in further studies. Nevertheless, the model exhibits its capability to capture the essential features of dam‐break flows with drying and wetting fronts. It also exhibits the potential to provide the basis for computationally efficient flood routing and warning information. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

3.
Previous studies have shown that water retention curve (WRC) and the hydraulic conductivity vary because of changes of the void ratio or porosity of soil. However, limited documents pointed out the change of hydraulic properties of soil when compacted to different porosities while considering both of the drying and wetting processes of the WRC. This information is sometimes necessary for research like finger flow analysis or the occurrence of wetting and drying cycles as what would be seen in the field. Therefore, this study aims to examine the change of WRC characteristics with varied porosity considering both of the drying and wetting path in WRC by conducting a sand box experiment. Results show that the same type of sand compacted to various porosities have different hydraulic parameters. Hydraulic conductivities generally decrease with reduced porosities; shape parameter α of the van Genuchten equation (1980) linearly decreases with declining porosity and shape parameter n in a reversal manner for the sands of interest whether in the drying process or wetting process. The unsaturated properties of sand are further characterized by inspecting the variations of moisture content, matric suction and vertical displacement of soil body subject to periodic changes of the water level by another sand box experiment. The outcomes suggest that the saturated water content and residual water content are changing during the wetting–drying process, which can be an implication of the changed properties of WRC. The characteristics of volumetric deformation might be varied as well because of the observation of the dissimilar patterns of the changing vertical displacements among each wetting–drying process. Infiltration patterns of the sands also are identified through numerical modelling by introducing a constant infiltration flux from the surface followed by a no‐influx condition. Results indicate that less water accumulates in the sand near the surface for the sand compacted to higher porosity, but water can move deeper. Hydraulic conductivity is found as the prime factor dominating the evolvement of wetting fronts. However, shape parameters of water retention curves also affect the infiltration pattern to some extent. In addition, different sands with similar porosities can have quite different infiltrating characteristics. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

4.
This work proposes a method for detecting inundation between semi‐diurnal low and high water conditions in the northern Gulf of Mexico using high‐resolution satellite imagery. Radarsat 1, Landsat imagery and aerial photography from the Apalachicola region in Florida were used to demonstrate and validate the algorithm. A change detection approach was implemented through the analysis of red, green and blue (RGB) false colour composites image to emphasise differences in high and low tide inundation patterns. To alleviate the effect of inherent speckle in the SAR images, we also applied ancillary optical data. The flood‐prone area for the site was delineated a priori through the determination of lower and higher water contour lines with Landsat images combined with a high‐resolution digital elevation model. This masking technique improved the performance of the proposed algorithm with respect to detection techniques using the entire Radarsat scene. The resulting inundation maps agreed well with historical aerial photography as the probability of detection reached 83%. The combination of SAR data and optical images, when coupled with a high‐resolution digital elevation model, was shown to be useful for inundation mapping and have a great potential for evaluating wetting/drying algorithms of inland and coastal hydrodynamic models. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

5.
This work proposes two modelling frameworks for diagnosing temporal variations in nonlinear rating curves that describe suspended sediment–discharge relationships. A variant of the weighted regression on time, discharge, and season model is proposed and is compared against dynamic nonlinear modelling, a newly developed nonlinear time series filter based on sequential Monte Carlo sampling. Both approaches estimate a time series of rating curve parameters, with uncertainty, that can be used to diagnose variability in the sediment–discharge relationship over time. We evaluate the models with a variety of synthetic scenarios to highlight their ability to estimate signals of known rating curve change. Results reveal important bias‐variance trade‐offs unique to each approach, and in general, suggest that dynamic nonlinear modelling is better suited for rapid rating curve changes, whereas the weighted regression on time, discharge, and season variant more precisely estimates slow change. The techniques are then applied in two case studies in the Upper Hudson and Mohawk Rivers in New York. We conclude with a discussion of the implications of dynamic rating curves for the management of water quality in riverine and estuary systems.  相似文献   

6.
This study presents time‐varying suspended sediment‐discharge rating curves to model suspended‐sediment concentrations (SSCs) under alternative climate scenarios. The proposed models account for hysteresis at multiple time scales, with particular attention given to systematic shifts in sediment transport following large floods (long‐term hysteresis). A series of nested formulations are tested to evaluate the elements embedded in the proposed models in a case study watershed that supplies drinking water to New York City. To maximize available data for model development, a dynamic regression model is used to estimate SSC based on denser records of turbidity, where the parameters of this regression are allowed to vary over time to account for potential changes in the turbidity‐SSC relationship. After validating the proposed rating curves, we compare simulations of SSC among a subset of models in a climate change impact assessment using an ensemble of flow simulations generated using a stochastic weather generator and hydrologic model. We also examine SSC estimates under synthetic floods generated using a peaks‐over‐threshold model. Our results indicate that estimates of extreme SSC under new climate and hydrologic scenarios can vary widely depending on the selected model and may be significantly underestimated if long‐term hysteresis is ignored when simulating impacts under sequences of large storm event. Based on the climate change scenarios explored here, average annual maximum SSC could increase by as much as 2.45 times over historical values.  相似文献   

7.
This paper proposes a new set of probabilistic joint shear strength models using the conventional multiple linear regression method, and advanced machine‐learning methods of multivariate adaptive regression splines (MARS) and symbolic regression (SR). In order to achieve high‐fidelity regression models with reduced model errors and bias, this study constructs extensive experimental databases for reinforced and unreinforced concrete joints by collecting existing beam‐column joint subassemblage tests from multiple sources. Various influential parameters that affect joint shear strength such as material properties, design parameters, and joint configuration are investigated through tests of statistical significance. After performing a set of regression analyses, the comparison of simulation results indicates that MARS approach is the best estimation method. Moreover, the accuracy of analytical predictions of the derived MARS model is compared with that of existing joint shear strength relationships. The comparison results show that the proposed model is more accurate compared to existing relationships. This joint shear strength prediction model can be readily implemented into joint response models for evaluation of earthquake performance and inelastic responses of building frames. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
Thus far, measurements and estimations of actual evapotranspiration (ET) from high‐altitude grassland ecosystems in remote areas like the Qinghai‐Tibetan plateau are still insufficient. To address these issues, a comparison between the results of the eddy covariance (EC) measurements and the estimates, considering the Katerji and Perrier (KP), the Todorovic (TD) and the Priestley–Taylor (PT) models, was carried out over an alpine grassland (38o03'1.7'' N, 100o 27’ 26'' E; 3032 m a.s.l.) during the growing seasons in 2008 and 2009. The results indicated that the KP model after a particularly simple calibration gave the most effective ET values in different time scales, the PT model slightly underestimate ET at night and the TD model significantly overestimated ET at noon. In addition, the canopy resistance calculated by the TD model was completely different from that calculated using the inverted EC‐measured data and the KP model, which may be due to some unrealistic assumptions made by the TD model. The KP parameters were a = 0.17 and b = 1.50 for the alpine grassland and appeared to be interannually stable. However, the PT parameter showed some interannual variations (α = 0.83 and 0.74 for 2008 and 2009, respectively). Therefore, the KP model was preferred to estimate the actual ET at both hourly and daily time scales. The PT model, being the simplest approach and field condition dependent, was recommended when available weather data were rare. On the contrary, the TD model always overestimated the actual ET and should be avoided in case of the alpine grassland ecosystems. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

9.
Forest evapotranspiration is one of the main components in the regional water budget. A comparison between measured and estimated eddy covariance (EC) data, considering the Katerji–Perrier (KP), Todorovic (TD) and Priestley–Taylor (PT) actual evapotranspiration methods, was carried out. These models, relying on more easily obtainable data, are valuable when long‐term direct measurements are not available. The objective of this paper is to compare the effectivity of these three models. In this paper, experimental data were obtained within the temperate mixed forest of broad‐leaved and coniferous trees of the Changbai Mountains in northeastern China during the growing seasons of 2003 to 2005. The KP method gave the most effective values for half‐hourly and daily evapotranspiration computed by summing up half‐hourly estimates, and the TD method overestimated evapotranspiration by about 30%. The diurnal courses of estimated and measured evapotranspiration showed bell curves, similar to that of net radiation, except for a slight increase at about 14:30 solar time due to a peak value of vapour pressure deficit (VPD). For the case of daily evapotranspiration using daily mean micrometeorological variables, the PT method presented the closest values to the measurements. Accuracy of estimation related to VPD negatively (especially for VPD > 1·5 kPa). The KP parameters, considered to be vegetation dependent, were a = 0·545 and b = 1·31 at the experimental site. A constant PT parameter (α = 1·18) was applied to estimated evapotranspiration. Daily values of α responded to VPD (negatively) more strongly than to soil moisture (positively) in this forest. The experiment showed the inherent limits and advantages of the three methods. The KP method, a semi‐empirical approach, was preferred to estimate half‐hourly evapotranspiration. The TD method was a mechanistic approach to estimate reference evapotranspiration and always overestimated actual evapotranspiration. The PT method, being site dependent and the simplest approach, was effective enough to estimate large time‐scale (at least daily) evapotranspiration. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

10.
Laboratory experiments were used to investigate the influence of simulated cracks and roots on soil water repellency (SWR) dynamics with and without basal drainage impedance in wetting–drying cycles. Observations and measurements were taken following water application equivalent to 9.2‐mm rainfall and then periodically during 80 h of drying. In total, 180 experiments were carried out using 60 samples of three homogeneous, reconstituted soils with different organic matter contents and textures, but of similar initial severity of SWR [18% molarity of an ethanol droplet (MED)]. Water flowing down the cracks and roots left the soil matrix largely dry and water repellent except for vertical zones adjacent to them and a shallow surface layer. A hydrophilic shallow basal layer was produced in experiments where basal drainage was impeded. During drying, changes in SWR were largely confined to the zones that had been wetted. Soil that had remained dry retained the initial severity of SWR, while wetted soil re‐established either the same or slightly lower severity of SWR. In organic‐rich soil, the scale of recovery to pre‐wetting MED levels was much higher, perhaps associated with temporarily raised levels (up to 36% MED) of SWR recorded during drying of these soils. With all three soils, the re‐establishment of the original SWR level was less widespread for surface than subsurface soil and with impeded than unimpeded basal drainage. Key findings are that as follows: (1) with unimpeded basal drainage, the soils remained at pre‐wetting repellency levels except for a wettable thin surface layer and zones close to roots and cracks, (2) basal drainage impedance produced hydrophilic basal and surface layers, (3) thorough wetting delayed a return to water‐repellent conditions on drying, and (4) temporarily enhanced SWR occurred in organic‐rich soils at intermediate moisture levels during drying. Hydrological implications are discussed, and the roles of cracks and roots are placed into context with other influences on preferential flow and SWR under field conditions. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

11.
Long‐term weathering of a quartz chlorite schist via wetting and drying was studied under a simulated tropical climate. Cubic rock samples (15 mm × 15 mm × 15 mm) were cut from larger rocks and subjected to time‐compressed climatic conditions simulating the tropical wet season climate at the Ranger Uranium Mine in the Northern Territory, Australia. Fragmentation, moisture content and moisture uptake rate were monitored over 5000 cycles of wetting and drying. To determine the impact of climatic variables, five climatic regimes were simulated, varying water application, temperature and drying. One of the climatic regimes reproduced observed temperature and moisture variability at the Ranger Uranium Mine, but over a compressed time scale. It is shown that wetting and drying is capable of weathering quartz chlorite schist with changes expected over a real time period of decades. While wetting and drying alone does produce changes to rock morphology, the incorporation of temperature variation further enhances weathering rates. Although little fragmentation occurred in experiments, significant changes to internal pore structure were observed, which could potentially enhance other weathering mechanisms. Moisture variability is shown to lead to higher weathering rates than are observed when samples are subjected only to leaching. Finally, experiments were conducted on two rock samples from the same source having only subtle differences in mineralogy. The samples exhibited quite different weathering rates leading to the conclusion that our knowledge of the role of rock type and composition in weathering is insufficient for the accurate determination of weathering rates. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

12.
Nested circulation models developed to date either exclude the flooding and drying process or prohibit flooding and drying of nested boundaries; they are therefore ill-suited to the accurate modelling of inter-tidal areas. The authors have developed a nested model with moving boundaries which permits flooding and drying of both the interior domain and the nested boundaries. The model uses a novel approach to boundary formulation; ghost cells are incorporated adjacent to the nested boundary cells so that the nested boundaries operate as internal boundaries. When combined with a tailored adaptive interpolation technique, the approach facilitates a dynamic internal boundary. Details of model development are presented with particular emphasis on the treatment of the nested boundary. Results are presented for Cork Harbour, a natural coastal system with an extensive inter-tidal zone and a complex flow regime which provided a rigorous test of model performance. The nested model was found to achieve the accuracy of a high resolution single grid model for a much lower computational cost.  相似文献   

13.
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14.
The presence of scaling statistical properties in temporal rainfall has been well established in many empirical investigations during the latest decade. These properties have more and more come to be regarded as a fundamental feature of the rainfall process. How to best use the scaling properties for applied modelling remains to be assessed, however, particularly in the case of continuous rainfall time‐series. One therefore is forced to use conventional time‐series modelling, e.g. based on point process theory, which does not explicitly take scaling into account. In light of this, there is a need to investigate the degree to which point‐process models are able to ‘unintentionally’ reproduce the empirical scaling properties. In the present study, four 25‐year series of 20‐min rainfall intensities observed in Arno River basin, Italy, were investigated. A Neyman–Scott rectangular pulses (NSRP) model was fitted to these series, so enabling the generation of synthetic time‐series suitable for investigation. A multifractal scaling behaviour was found to characterize the raw data within a range of time‐scales between approximately 20 min and 1 week. The main features of this behaviour were surprisingly well reproduced in the simulated data, although some differences were observed, particularly at small scales below the typical duration of a rain cell. This suggests the possibility of a combined use of the NSRP model and a scaling approach, in order to extend the NSRP range of applicability for simulation purposes. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

15.
As illustrated variously by wetting and drying scanning curves, flow in unsaturated porous media is inherently nonlocal. This nonlocality is also manifest in hysteresis in the classical Darcy conductivity. It is the authors' belief that most current theories of unsaturated/saturated flow are often inadequate, as they do not account for spatial nonlocality and memory. Here we provide a fundamental theory in which nonlocality of the flow constitutive theory is a natural consequence of force balances. The results are derived from general principles in statistical physics and under appropriate limiting conditions, the classical Darcy's Law is recovered for saturated flow. A notable departure in this theory from other nonlocal flow theories is that a classical Darcy type equation on a small scale need not exist.  相似文献   

16.
Hysteresis is a common feature exhibited in hydraulic properties of an unsaturated soil. The movement of wetting front and the hysteresis effect are important factors which impact the shear strength of the unsaturated soil and the mechanics of shallow landslides. These failures are mainly triggered by the deepening of the wetting front accompanied by a decrease in matric suction induced by infiltration. This research establishes a method for determining a stability analysis of unsaturated infinite soil slopes, integrating the influence of infiltration and the water retention curve hysteresis. Furthermore, the present stability analysis method including the infiltration model and the advanced Mohr–Coulomb failure criterion calculates the variations of the safety factor (FS) in accordance with different slope angle, depth and hydrological processes. The experimentally measured data on the effect of hysteresis are also carried out for comparison. Numerical analyses, employing both wetting and drying hydraulic behaviour of unsaturated soil, are performed to study the difference in soil‐water content as observed in the experiments. The simulating approximations also fully responded to the experimental data of sand box. The results suggest that the hysteresis behaviour affect the distribution of soil‐water content within the slope indeed. The hysteresis made the FS values a remarkable recovery during the period of non‐rainfall in a rainfall event. The appropriate hydraulic properties of soil (i.e. wetting or drying) should be used in accordance with the processes that unsaturated soil actually experience. This method will enable us to acquire more accurate matric suction head and the unsaturated soil‐shear strength as it changes with the hysteretic flow, in order to calculate into the stability analysis of shallow landslides. An advanced understanding of the process mechanism afforded by this method is critical to realizing a reliable and appropriate design for slope stabilization. It also offers some immediate reference information to the disaster reduction department of the government. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

17.
Taiwan is surrounded by the sea, and the southwestern seashores are suffering from a growing land subsidence problem caused by the excessive extraction of groundwater. There is also very serious intrusion by seawater along the coastline. These circumstances obstruct any land use, soil remediation or agriculture development in the area. When seawater intrudes, salt gets into the soil. The infiltration, evapotranspiration and the distribution of salinity in the unsaturated soil become a very complex problem. It is vital to investigate the hysteresis of soil water‐retention curves, combined with the salinity in these areas. Therefore, this study's main focus will be the calibration of variations in salinity and their effect on the hysteresis of soil water‐retention curves. In the wetting processes, the salty soil water‐retention curves undergo an upper shift compared with the original soil water‐retention curves because of the higher tension of saltwater. In the drying processes, there is also an upper shift compared with the original curves because the salinity influences the air‐entry pressure. The saltwater's high salinity causes the hysteresis of soil water‐retention curves to experience a greater shift. The changes in salinity also cause changes to the hysteresis curves’ shape factors, which conforms to Huang's model (developed by Huang H.C., Y.C. Tan, C.W. Liu, and C.H. Chen in 2005), the values of α and n. The value of α decreases with the increased salinity. The trend of the n value presents an irregular result. A linear regression of the αw and αd values was advanced where the R‐square values of αw and αd exceeded 0.97. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

18.
D. Yu  S. N. Lane 《水文研究》2006,20(7):1567-1583
This paper develops and tests a sub‐grid‐scale wetting and drying correction for use with two‐dimensional diffusion‐wave models of urban flood inundation. The method recognizes explicitly that representations of sub‐grid‐scale topography using roughness parameters will provide an inadequate representation of the effects of structural elements on the floodplain (e.g. buildings, walls), as such elements not only act as momentum sinks, but also have mass blockage effects. The latter may dominate, especially in structurally complex urban areas. The approach developed uses high‐resolution topographic data to develop explicit parameterization of sub‐grid‐scale topographic variability to represent both the volume of a grid cell that can be occupied by the flow and the effect of that variability upon the timing and direction of the lateral fluxes. This approach is found to give significantly better prediction of fluvial flood inundation in urban areas than traditional calibration of sub‐grid‐scale effects using Manning's n. In particular, it simultaneously reduces the need to use exceptionally high values of n to represent the effects of using a coarser mesh process representation and increases the sensitivity of model predictions to variation in n. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

19.
A periodic vertical movement of the groundwater table results in a subsequent cyclic response of the water content and pressure profiles in the vadose zone. The sequence of periodic wetting and drying processes can be affected by hysteresis effects in this zone. A one-dimensional saturated/unsaturated flow model based on Richards’ equation and the Mualem (Soil Sci. 137 (1984) 283) hysteresis model is formulated which can take into account multi-cycle hysteresis effects in the relation between capillary pressure and water content. The numerical integration of the unsaturated flow equation is based on a Galerkin-type finite element method. The flow domain is discretised by finite elements with linear shape functions. Simulations start with static water content and pressure profiles, which correspond to either a boundary drying or wetting retention curve. To facilitate the numerical solution of the hysteretic case an implicit non-iterative procedure was chosen for the solution of the nonlinear differential equation. Laboratory experiments were performed with a vertical sand column by imposing a high frequency periodic pressure head at the lower end of the column. The total water volume in the column, and the periodic water content profile averaged over time were measured. The boundary drying and wetting curves of the relation between water content and capillary pressure were determined by independent experiments. The simulations of the experimental conditions show a clear effect of the hysteresis phenomenon on the water content profile. The simulations with hysteresis agree well with the measurements. Computed dimensionless water content profiles are presented for different oscillation frequencies with and without consideration of hysteresis.  相似文献   

20.
Coupled groundwater–surface water (GW–SW) models are capable of simulating complex hydrological systems when used at fine resolutions. However, properly characterizing bulk GW–SW fluxes for either coarsely resolved integrated models or basin‐discretized surface water models remains a challenge. Loss of subgrid detail, while beneficially decreasing computational cost, leads to a decrease in model accuracy as scale effects become important. Ideally, coarse low‐resolution models should be informed by expected subgrid behaviour, reducing the impact of scale effects. Determining how to best represent these fine‐scale details in lower‐resolution models is important for improving the accuracy and appropriateness of these models. To investigate some of these scale effects, we here explore the relationships between area‐averaged hydraulic head and bulk GW–SW exchange fluxes (e.g. evapotranspiration and discharge), all of which are presumed to be controlled predominantly by subgrid topographic effects. These relationships may be useful for simply upscaling models without the complete loss of crucial fine‐resolution subgrid details. Using finely resolved simulation output from Modflow for a fine‐resolution simulation and post‐processed results generated to represent coarser resolutions, upscaled flux relationships (UFRs) are generated for multiple terrains; these UFRs define the relationships that exist between average hydraulic head and average fluxes in unconfined aquifer systems. It is found that, for steady‐flow regimes, similar one‐to‐one power law relationships consistently exist between area‐averaged hydraulic heads, exchange fluxes and saturated area for a variety of terrains. Additionally, when the averaged values are properly normalized, the generated steady‐state UFRs for a single terrain are independent of hydraulic conductivity and potential evapotranspiration rates and apparently insensitive to the presence of mild heterogeneity. While some hysteresis is apparent in the relationships under transient conditions, transient artefacts are shown to be minor under some circumstances, indicating that UFRs may be applied to both steady‐state and transient scenarios. Simpler tests performed under saturated and variably saturated conditions in a cross‐sectional model show similar trends, suggesting that the UFR representation is extendable to systems where the vadose zone plays a significant role. It is suggested that relatively simple UFRs such as these may find use as an alternative to direct point upscaling or multi‐resolution models for estimating GW–SW exchange fluxes in coarse‐scale models. They also appear to justify the functional form of some classical models of baseflow and evapotranspiration used in conceptual surface water models. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

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