Among the uncertain consequences of climate change on agriculture are changes in timing and quantity of precipitation together with predicted higher temperatures and changes in length of growing season. The understanding of how these uncertainties will affect water use in semiarid irrigated agricultural regions depends on accurate simulations of the terrestrial water cycle and, especially, evap...

Fluxes of water, energy and carbon dioxide (CO2) were measured using the eddy covariance technique over a mesquite (Prosopis velutina) woodland along the San Pedro River in southeastern Arizona for the entire growing seasons of 2001 and 2002, between the last freeze event of spring and the first of fall. Although the general pattern of ecosystem response to climate forcing was similar in both y...

The AnnAGNPS pollution model uses evapotranspiration as one of the inputs to predict runoff, sediment, nutrients, and pesticide contributions from land to streams. This modeling tool has been modified to accept evapotranspiration estimates derived from remotely sensed imagery, produced by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. This research evaluated the next generati...

Remotely sensed images of the Earth’s surface provide information about the spatial distribution of evapotranspiration. Since the spatial resolution of evapotranspiration predictions depends on the sensor type; scaling transfer between images of different scales needs to be investigated. The objectives of this study are first to validate the consistency of SEBAL algorithms for satellite images ...

Dryland ecosystems cover 40% of the total land surface on Earth and are defined broadly as zones where precipitation is considerably less than the potential evapotranspiration. Nonrainfall waters (for example, fog and dew) are the least-studied and least-characterized components of the hydrological cycle, although they supply critical amounts of water for dryland ecosystems. The sources of nonr...

The changing of climate directly affects on decreasing agricultural production. Therefore, application of automated system in agriculture activities is potential issue which must be considered. This paper presents error analysis of ON-OFF and ANN controllers which are applied to the automated irrigation system. Controlling of irrigation system used a calculated Penman-Monteith evapotranspiratio...

Terrestrial ecosystems greatly contribute to carbon (C) emission reduction targets through photosynthetic C uptake.Net primary production (NPP) represents the amount of atmospheric C fixed by plants and accumulated as biomass. The Three-North Shelterbelt Program (TNSP) zone accounts for more than 40% of China's landmass. This zone has been the scene of several large-scale ecological restoration...

Evapotranspiration, a major component in terrestrial water balance and net primary productivity models, is difficult to measure and predict. This study compared five models of potential evapotranspiration (PET) applied to a ponderosa pine forest ecosystem at an AmeriFlux site in Northern California. The AmeriFlux sites are research forests across the United States, Canada, Brazil, and Costa Ric...

Restoration activities in the Central Valley of California and elsewhere require accurate evapotranspiration information, which can then be used for a wide variety of surface and subsurface hydrologic evaluations. However, directly measuring evapotranspiration can be difficult or impossible depending on the evaluation’s time frame. Transferability of measured evapotranspiration in time and spac...

Evapotranspiration is one of the major parameter in the hydrologic cycle. Standard measurements of this parameter is quite complex due to various factors such as variation of precipitation amount, spatial variation by latitude and longitude and changes in environment and specific site conditions. Although of this complexity, various methods were developed to estimate actual and potential Evapot...