an accurate determination of evapotranspiration is required for many studies that involve estimation of the water balance. one methodology is the use of lysimeters. considering the semiarid climate of kerman province, in southeastern parts of iran, the only operating electronic weighing lysimeter in the country was used for calculating daily eto from april 2004 to march 2005 in three different ...

been reviewed in final form. Permission, as indicated by the signatures and dates given below, is now granted to submit final copies to the College of Graduate Studies for approval. Abstract Changes in streamflow across the western US illustrate a need to better understand how drought indices derived from climate data track streamflow. Three drought metrics, the (SPEI), and Palmer Drought Sever...

Establishing satisfactory calculation methods of lake evaporation has been crucial for research and management of water resources and ecosystems. A 30 year dataset from Dickie Lake, south-central Ontario, Canada added to the limited long-term studies on lake evaporation. Evaporation during ice-free season was calculated separately using seven evaporation methods, based on field meteorology, hyd...

from the mathematical point of view, the fao penman-monteith equation shows a homographic function related to the wind speed. the homographic function has horizontal and vertical asymptotes. in this issue horizontal asymptote is applicable; because the vertical asymptote occurs for negative values of wind speed but the negative sign indicates the direction of the wind speed and only the absolut...

The use of multiple evapotranspiration (ET) models is critical for exploring the ambiguity in the representations of ET processes. Although ensemble ET models are increasingly used to address this ambiguity, practical issues include: 1) the diversity of process representations, which require different input data and constants; 2) the diversity of nomenclature, terminology and units used in the ...

In both Australia and Swaziland large areas of sugarcane rely on irrigation to produce a viable crop or to improve rainfed productivity. Matching water supply to crop demand is essential for productivity and sustainability in any irrigation scheme. Historically Class-A pan evaporation was used as a basis for determining sugarcane water demand or evapotranspiration (ETc). ETc is now frequently o...

For the Penman±Monteith equation to be used to predict crop evapotranspiration in a one-step approach, methodologies for determining surface resistance (rs) must be available. One usual approach to the modelling of rs is to compute it by inverting the Penman±Monteith equation and then relate it to the most important environmental variables (radiation, temperature, vapour pressure deficit) using...

Knowing the rate of evapotranspiration (ET) from surface water resources such as lakes and reservoirs is essential for the precise management of water balance. Ardestan city with hot and dry climate is in Isfahan province (center of Iran), so in this region, water is very important. In this study, monthly ET was determined by several methods and equations for Ardestan city from 1993-2006. Month...

In order to better manage the limited water resources in arid regions, accurate determination of plant water requirements is necessary. For that, the evaluation of reference evapotranspiration (ET0)--a basic component of the hydrological cycle--is essential. In this context, the Penman Monteith equation, known for its accuracy, requires a high number of climatic parameters that are not always f...

[1] The Penman-Monteith equation is often used to estimate transpiration, but an important limitation to this approach, especially for mountainous forested sites, is an accurate estimate of canopy conductance averaged over the area of interest (Gs). We propose a method for estimating watershed-scale transpiration using estimates of Gs derived from measurements of stable isotopes. To estimate Gs...