نتایج جستجو برای: bear soil evaporation
تعداد نتایج: 218764 فیلتر نتایج به سال:
Evaporation coefficient (KE) is defined as the ratio of actual evaporation over potential evaporation under the same atmospheric conditions. The use of KE provides an alternative means for evaluating soil moisture status and quantifying soil evaporation by reducing in situ measurements. However, little effort has been made to evaluate the estimation of KE over soil surfaces. In this study, a re...
Crop coefficient curves provide simple, reproducible means to estimate crop evapotranspiration (ET) from weather-based reference ET values. The dual crop coefficient sKcd method of the Food and Agricultural Organization of the United States (FAO) Irrigation and Drainage Paper No. 56 (FAO-56) is intended to improve daily simulation of crop ET by considering separately the contribution of evapora...
Literature regarding evaporation from soil, wet plant surfaces, and sprinkler droplets was examined, normalized, and inter preted. Much of the evaporation literature is difficult to compare and interpret; this paper offers comparisons and discussions of various findings by others as well as by the writers. Techniques of measuring and estimating evaporation from irrigation and rainfall are disc...
In an effort to develop methods based on integrating the subsurface to the atmospheric boundary layer to estimate evaporation, we developed a model based on the coupling of Navier-Stokes free flow and Darcy flow in porous medium. The model was tested using experimental data to study the effect of wind speed on evaporation. The model consists of the coupled equations of mass conservation for two...
Soil surface resistance increase quickly during the first three days after irrigation or rain event. By explicitly incorporating surface resistance in simple equations, daily total evaporation estimation of a drip-irrigated olive grove was significantly improved. This increase in soil surface resistance could explain why observed cumulative soil evaporation is higher in locations with lower irr...
Using a fully coupled climate–terrestrial ecosystem model, we demonstrate explicitly that an initial perturbation on vegetation induces not only a direct positive vegetation feedback, but also a significant indirect vegetation–soil moisture feedback. The indirect feedback is generated through either fractional cover change or soil moisture depletion. Both indirect feedback mechanisms are trigge...
Tillage-induced changes in soil properties are difficult to predict, yet can influence evaporation, infiltration and howwater is redistributedwithin the profile after precipitation.We evaluated the effects of sweep tillage (ST) on near surface soil water dynamics as compared with an untilled (UT) soil during a 7-month period. Plots were established in a fallow field devoid of residue under stub...
The present paper proposes a method for the evaluation of soil evaporation, using soil moisture estimations based on radar satellite measurements. We present firstly an approach for the estimation and monitoring of soil moisture in a semi-arid region in North Africa, using ENVISAT ASAR images, over two types of vegetation covers. The first mapping process is dedicated solely to the monitoring o...
The 12 weather and climate models participating in the Global Land–Atmosphere Coupling Experiment (GLACE) show both a wide variation in the strength of land–atmosphere coupling and some intriguing commonalities. In this paper, the causes of variations in coupling strength—both the geographic variations within a given model and the model-to-model differences—are addressed. The ability of soil mo...
A physically based, variably saturated flow model was developed to predict soil water dynamics, evapotranspiration (ET) from the vadose zone, and recharge to (or exfiltration from) the saturated zone using mean daily atmospheric forcings and to identify the value of diurnal climate forcings on those predictions. The vadose zone flow is modelled using the Galerkin finite element technique to sol...
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