An integrated hydrological and meteorological approach for the simulation of terrestrial evapotranspiration / Une approche hydrologique et météorologique intégrée pour la simulation de l'évapotranspiration terrestre     

《水文科学杂志》2013,58(6):1151-1164

Abstract

Terrestrial evapotranspiration (ET) plays an important role in determining water and heat balances in the water cycle between the land surface and the atmosphere. In the present research a dynamic approach is developed to simulate actual ET distribution for large-scale spatial and temporal scales based on an integration of meteorological and hydrological methods. The method developed has been used to examine the impacts of climate change, complex land cover features, and soil moisture on actual ET. The distribution characteristics of actual ET demonstrate that ET in eastern China is greater than that in western China, and that ET is greater in low-latitude regions of China than in high-latitude regions. Actual monthly and annual ET values in most regions show an increasing tendency from the year 1991 to 2000, especially in arid and semi-arid regions. The results of the present study also confirm that soil moisture is one of the critical factors that affect regional ET in China. It is demonstrated that the integrated hydrological-meteorological approach is effective for simulating actual ET on large spatial and temporal scales.  相似文献   

Flow and transport through two-dimensional isotropic media of binary conductivity distribution. Part 1: NUMERICAL methodology and semi-analytical solutions     

A.?FioriEmail author  I.?Jankovic  G.?Dagan 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(6):370-383

Flow and transport take place in a heterogeneous medium made up from inclusions of conductivity K submerged in a matrix of conductivity K ₀. We consider two-dimensional isotropic media, with circular inclusions of uniform radii, that are placed at random and without overlap in the matrix. The system is completely characterized by the conductivity contrast =K/K ₀ and by the volume fraction n. The flow is uniform in the mean, of velocity U=const. The derivation of the velocity field is achieved by a numerical method of high accuracy, based on analytical elements. Approximate analytical solutions are derived by a few methods: composite elements, effective medium, dilute systems and first-order approximation in logconductivity variance. The latter was employed by Rubin (1995), while the dilute system approximation was used by Eames and Bush (1999) and Dagan and Lessoff (2001). Transport is solved in a Lagrangean framework, with trajectories determined numerically from the velocity field, by particle tracking. Results for the velocity variance and for the longitudinal macrodispersivity, for a few values of and n, are presented in Part 2.  相似文献   

Hydrological management of a cutover peatland     

A. L. Heathwaite 《水文研究》1994,8(3):245-262

Mechanisms for preserving the hydrological balance of Thorne Moors National Nature Reserve (NNR) while allowing peat extraction to continue in the surrounding peatland are examined. Three strategies exist for modifying seepage losses from the NNR: (I) re-direction of pump drainage waters from the peat extraction areas; (II) provision of a hydrological buffer zone around the NNR; and (III) mechanical compaction of the boundaries of the buffer zone. Strategy II (increased width of the buffer zone) should be used together with strategy III (compaction) for the maximum reduction of seepage losses from the NNR. If strategy I (water level manipulation) is also adopted, it may be possible to reduce the width of the hydrological buffer zone around the NNR.  相似文献   

Nutrient chemistry and hydrology of interstitial water in brackish tidal marshes of Chesapeake Bay     

Thomas E. Jordan  David L. Correll 《Estuarine, Coastal and Shelf Science》1985,21(1):45-55

Nutrient concentrations in interstitial water were measured throughout the year in two brackish tidal marshes differing in elevation and vegetation. At all sites, sulfate to chloride ratios were lowest during the fall. In contrast, dissolved ammonia, phosphate, organic nitrogen, and organic phosphorus concentrations did not vary seasonally but differed among sample sites. These nutrients were generally enriched in interstitial water relative to tidal water and those that were most enriched declined in concentration with increasing proximity to creeks. In the low elevation marsh, flow of interstitial water towards creek banks was traced with Rhodamine WT dye. Consequent seepage of interstitial water into the creek of the low marsh was estimated from continuous monitoring of water table heights and from measurements of hydraulic conductivity. The estimated seepage could account for a portion, probably less than half, of the tidal export of dissolved nutrients from the low marsh.  相似文献   

An analysis of methods for calculating constant terminal-settling velocities of spheres in liquids     

J. B. Warg 《Mathematical Geology》1973,5(1):59-72

Methods for calculating constant terminal-settling velocities (v_s)of spheres are examined for their validity and limitations of usefulness. A different approach is given which accurately predicts v_s for spheres over a wide range of hydraulic conditions based on past experimental work. The theory behind this approach is given along with the listing of a fortran program which directs the calculations of v_s.The practical limits of the author's method are stated, and tables of v_s may be generated from the program for common mineral densities over a range of sizes useful to sedimentologists.  相似文献   

The interaction between hydrology and geomorphology in a landscape simulator experiment     

Greg Hancock  Garry Willgoose 《水文研究》2001,15(1):115-133

An experimental landscape simulator has been developed which uses a rainfall simulator to create overland flow and erosion. The simulator uses rainfall sprinklers that eliminate rainsplash and an artificial soil which has little cohesion. Experimental landscapes developed in the simulator evolved according to Howard's headward growth model. Elements of Glock's model could be identified during evolution (i.e. initiation and maximum extension), but other stages of this model were not observed (i.e. extension and integration). The Horton concept of cross‐grading and micropiracy and stream piracy was not observed despite the dominance of overland flow, nor the groundwater headward growth mechanism proposed by Dunne, the latter due to experimental design, which eliminated any perched groundwater table. The experimental apparatus produced model landscapes that are scaled‐down analogues of real world processes. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

The link between glacier velocity and the drainage of ice-dammed lakes: Comment on a paper by knight and tweed     

D. M. Lawler 《水文研究》1994,8(5):447-456

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Probing the relationship between surface waters and aquifers by <Superscript>18</Superscript>O measurements on the top of the Araripe Plateau/NE Brazil     

Luiz?Alberto?Ribeiro?Mendon?a  Horst?FrischkornEmail author  Maria?Marlúcia?Freitas?Santiago  Josué?Mendes Filho 《Environmental Geology》2004,46(2):295-302

The Araripe Plateau in northeastern Brazil has an area of about 8,000 km², confined by 39°05E and 40°55E, and 7°10S and 7°50S. Due to high permeability of soils, a surface drainage system is practically inexistent. Water is stored in excavations with clayey soil, the barreiros. Monthly samples were taken for ¹⁸O measurements, from September 1999 to August 2000, from four barreiros, three dug wells and five drilled wells. Results show that (1) groundwaters in the eastern part of the plateau are derived from present-day rainfall (¹⁸O–3.2), whereas groundwaters in the western portion are isotopically different (¹⁸O–5.0); (2) barreiros are strongly marked seasonally by elevated ¹⁸O during the dry period due to elevated evaporation; (3) a dug well at a distance of 30 m from a barreiro exhibits ¹⁸O similar to that of the reservoir, indicating a strong interaction between groundwater and surface water; and (4) a tubular well of 242-m depth, located in a fault, exhibits strong seasonal changes in ¹⁸O and electrical conductivity, revealing downward leakage between aquifers.  相似文献   

Dynamics of floodplain-island groundwater flow in the Okavango Delta, Botswana     

P. Wolski  H.H.G. Savenije   《Journal of Hydrology》2006,320(3-4):283-301

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Hydrodynamics of floodplain wetlands in a chalk catchment: The River Lambourn, UK     

T.R. Grapes  C. Bradley  G.E. Petts 《Journal of Hydrology》2006,320(3-4):324-341

Variations in floodplain channel water levels and valley floor groundwater levels (measured in piezometers and boreholes) are examined at selected points along the course of the River Lambourn, a chalk river in southern England. A local alluvial gravel aquifer in the valley bottom is associated with numerous small wetlands that extend over much of the river's perennial profile. Variations in hydraulic gradient between local borehole levels and/or floodplain channel water levels are described for three sites in the seasonal section of the channel at Bockhampton, East Garston and West Shefford. The results indicate that observed groundwater levels are closely associated with flows from discrete springs at the margins of the channel and floodplain. However, as the floodplain widens and the alluvial gravel aquifer increases in size, the gravel aquifer accounts for a substantial down-valley component of groundwater flow with a diffuse vertical water flux. In the lower catchment, the exchange of flows between the gravel aquifer and the river enables some attenuation of floodplain water-table variability, providing a stable hydrological regime for valley-bottom wetlands. Catchment controls upon the local, valley-bottom, wetland regime are demonstrated with the application of a simple groundwater model developed using MODFLOW. The model is used to simulate groundwater discharge to the river in the upper and lower catchment, in addition to the water level regime at selected points in the valley bottom in the lower catchment. The results demonstrate the importance of taking catchment-scale water flow into account when managing isolated wetlands in a permeable catchment.  相似文献