évapotranspiration de référence

2020

18.08

sigur rós popplagið

évapotranspiration de référence

Thèse de doctorat en Hydrologie continentale soutenue en 2011 à l'Université Cheikh Anta Diop de DakarÉvaluation de vingt méthodes d'estimation de l'évapotranspiration journalière de référence au Burkina FasoKnowledge of evapotranspiration (ET) is very important for water resources planning and management. ALLEN R.G., PEREIRA L.S., RAES D. et SMITH M. (1998) - Crop evapotranspiration. XU C.Y. Where the vegetation does not completely cover the soil, the resistance factor should indeed include the effects of the evaporation from the soil surface. MAHRINGER W. (1970) - Verdunstungsstudien am Neusiedler See. Gobin, P. Balandier, N. Korboulewsky, Y. Dumas, V. Seigner, et al., « Une strate herbacée monopoliste: quelle concurrence vis-à-vis de l’eau pour le peuplement adulte ? FG : Fada Ngouma. C'est une valeur pour une végétation choisie, dans des conditions hydriques réelles, permettant ensuite de déduire l'évapotranspiration pour d'autres couverts végétaux. The surface resistance parameters are often combined into one parameter, the 'bulk' surface resistance parameter which operates in series with the aerodynamic resistance. Dans les espaces continentaux, plus de 60 % de l'apport pluviométrique serait ainsi dissipé par évapotranspirationL'évapotranspiration potentielle et réelle varient considérablement selon les écosystèmes et parfois selon les saisons, dont en Lorsqu’on ne dispose que de données journalières on peut calculer l’évapotranspiration de référence à l’aide de la formule suivante, dérivée l’équation de Penman – Monteith (2). L'évapotranspiration (ET) est la combinaison de l'évaporation et de la transpiration. et OKUNADE D.A. "Evapotranspiration components determined by stable isotope, sap flow and eddy covariance techniques."

TRABERT W (1896) - Neue beobachtungen über verdampfungsgeschwindigkeitenTRAJKOVIC S (2007) - Hargreaves versus Penman-Monteith under humid conditions. Several empirical equations for the estimate of d, zThe 'bulk' surface resistance describes the resistance of vapour flow through the transpiring crop and evaporating soil surface. Because the resistance to diffusion of vapour strongly depends on crop height, ground cover, LAI and soil moisture conditions, the characteristics of the reference crop should be well defined and fixed. - Measurement and estimation of evaporation and evapotranspiration. ABTEW W. (1996) - Evapotranspiration measurement and modeling for three wetland systems in South Florida. 24 'Crop water requirements'. Consequently, the associated canopy and aerodynamic resistances will vary appreciably with time. et ALEXANDRIS S.G. (2015) - Solar radiation and relative humidity based, empirical method, to DALTON J. Auteur : Food and Agriculture Organization of the United Nations (2003) - Evapotranspiration estimation for South Florida. However, its use is difficult in some areas particularly in developing countries where climate data are not always available. The studies confirm the overestimation of the modified Penman introduced in FAO Irrigation and Drainage Paper No. Relating ETGrass, together with alfalfa, is a well-studied crop regarding its aerodynamic and surface characteristics and is accepted worldwide as a reference surface. Conditions d'accès : Avec redevance Cette équation est celle de … The study proved very revealing and showed the widely varying performance of the methods under different climatic conditions. One of the alternatives is then to use methods integrating fewer climatic variables. Archiv für Meteorologie Geophysik und BioklimatologieALEXANDRIS S., STRICEVIC R. et PATKOVIC S. (2008) - Comparative analysis of reference evapotranspiration from the surface of rainfed grass in central Serbia, calculated by six empirical methods against the Penman-Monteith formula. Ce mouvement de l'eau permet de déplacer les éléments nutritifs essentiels à travers la plante. Testing the accuracy of the methods under a new set of conditions is laborious, time-consuming and costly, and yet evapotranspiration data are frequently needed at short notice for project planning or irrigation scheduling design. and the roughness length governing momentum transfer, zThe roughness length governing transfer of heat and vapour, zAssuming a constant crop height of 0.12 m and a standardized height for This can be done for weather stations with full data sets by comparing ET The equation can be utilized for the direct calculation of any crop evapotranspiration as the surface and aerodynamic resistances are crop specific.The transfer of heat and water vapour from the evaporating surface into the air above the canopy is determined by the aerodynamic resistance: HRmin : moyenne des humidités relatives minimales journalières. PENMAN (1963), W. ABTEW (1996), J.D. wind speed, temperature and humidity at 2 m (zThe Leaf Area Index (LAI), a dimensionless quantity, is the leaf area (upper side only) per unit area of soil below it. Tmin : moyenne des températures minimales journalières. half of dense clipped grass is actively contributing to the surface heat To accommodate users with different data availability, four methods were presented to calculate the reference crop evapotranspiration (ETAdvances in research and the more accurate assessment of crop water use have revealed weaknesses in the methodologies. BU : Bur Dédougou.

The ASCE study analysed the performance of 20 different methods, using detailed procedures to assess the validity of the methods compared to a set of carefully screened lysimeter data from 11 locations with variable climatic conditions. Factors to convert common units to the standard unit are presented in Annex I.