نتایج جستجو برای: evapotranspiration

تعداد نتایج: 6966  

2012
Ketema Tilahun Zeleke Leonard John Wade

The rise in water demand for agriculture, industry, domestic, and environmental needs requires sagacious use of this limited resource. Since agriculture (mainly irrigation) is the major user of water, improving agricultural water management is essential. Efficient agricultural water management requires reliable estimation of crop water requirement (evapotranspiration). Evapotranspiration (ET) i...

اسلامیان, سید سعید , زارعیان, محمدجواد, عابدی کوپایی, جهانگیر ,

Abstract Knowing crop evapotranspiration at any time is very important in management of irrigation systems for greenhouse. Changes in evapotranspiration during the crop growth period are described by crop coefficient (Kc), which is defined as the ratio between crop evapotranspiration and reference evapotranspiration. This study was conducted to determine the evapotranspiration of cucumber, tom...

1999
Kell B. Wilson Dennis D. Baldocchi

The components of the surface energy balance were measured for 3 years over a broadleaved deciduous forest using the eddy covariance technique. Within years, the magnitude and distribution of fluxes was controlled by seasonal changes in solar radiation, drought, as well as leaf emergence and senescence. Evapotranspiration increased by a factor greater than five (from about 0.5 to 3 mm day−1) af...

2009
Corinne A. Barker Brian D. Amiro Hyojung Kwon Brent E. Ewers Julia L. Angstmann

The Canadian boreal forest consists of a mosaic of landscapes of varying soil drainage and forest age driven by wildfire. The hydrological consequences are complicated by plant responses to soil moisture and forest age, both potentially influencing evapotranspiration. Evapotranspiration was measured using the energy balance residual technique in 2006 and 2007 at forested upland and fen sites th...

2000
A. Upadhyaya H. S. Chauhan

The linearized Boussinesq equation incorporating the effect of evapotranspiration with appropriate initial and boundary conditions was solved analytically to predict a fall in the water table in a bi-level drainage system. It was assumed that the evapotranspiration rate decreases linearly with a reduction in the elevation of the water table above the drains. A special case of this solution (i.e...

2009
Mohammad Javad Amiri

Evapotranspiration (ET) is one of the major components of hydrologic cycle. Accurate estimation of this parameter is essential for studies such as water balance, irrigation system design and management, and water resources management. Generally we used climate data for calculating evapotranspiration from indirect methods. This study investigates the utility of artificial neural networks (ANNs) ...

2011
S. E. Thompson C. J. Harman A. G. Konings M. Sivapalan A. Neal P. A. Troch

[1] Watersheds can be characterized as complex space‐time filters that transform incoming fluxes of energy, water, and nutrients into variable output signals. The behavior of these filters is driven by climate, geomorphology, and ecology and, accordingly, varies from site to site. We investigated this variation by exploring the behavior of evapotranspiration signals from 14 different AmeriFlux ...

2005
C.-Y. Xu V. P. Singh

Three evapotranspiration models using the complementary relationship approach for estimating areal actual evapotranspiration were evaluated and compared in three study regions representing a large geographic and climatic diversity: NOPEX region in Central Sweden (cool temperate, humid), Baixi catchment in Eastern China (subtropical, humid), and the Potamos tou Pyrgou River catchment in Northwes...

2008
S. Opoku-Duah D.N.M. Donoghue T. P. Burt

This paper compares evapotranspiration estimates from two complementary satellite sensors - NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) and ESA's ENVISAT Advanced Along-Track Scanning Radiometer (AATSR) over the savannah area of the Volta basin in West Africa. This was achieved through solving for evapotranspiration on the basis of the regional energy balance equation, which wa...

1999
J. Eastham P. J. Gregory D. R. Williamson G. D. Watson

The losses of water by evapotranspiration and evaporation from soil were investigated during two seasons from wheat and lupin crops sown at two times. Evapotranspiration was measured using ventilated chambers and microlysimeters were used within the chambers to measure evaporation from the soil surface. These techniques allowed the partitioning of evapotranspiration into its two components. In ...

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