نتایج جستجو برای: modified penman equation
تعداد نتایج: 472208 فیلتر نتایج به سال:
مقدار تبخیر و تعرق حقیقی مزرعه یونجه واقع در باجگاه بوسیله روش تعادل آبیاری در 9 کرت آزمایشی و دولیسمتر از نوع وزنی بمنظور تعیین آب مصرفی گیاه یونجه تعیین شد. در طول مدت آزمایش مقدار آب موجود در خاک بوسیله نمونه برداری وزنی از خاک و دستگاه نوترون متر تعیین و مقدار تشعشع رسیده از خورشید بزمین و ساعات آفتابی روز نیز اندازه گیری شد. مقدار تبخیر و تعرق پتانسیل بوسیله روشهای modified blaney-criddle ...
this experiment aimed to determine evapotranspiration, and responses of some yield and quality parameters of subsurface drip irrigated broccoli (brassica oleraceae l.). treatments included water application when available soil moistures were depleted 30, 40, and 50% during both spring and autumn cultivations. under a semi-arid climatic condition of tokat, turkey, the experiment was carried out ...
So far, various methods have been presented for determining reference crop evapotranspiration in different parts of the world. The most popular and prestigious of them are probably the combined methods of Penman family, modified Blany-Criddle, Hargreaves - Samani and thornthwaite. Due to lack of lysimeter data in many parts of Iran, presenting an equation according to the regional condition wit...
Estimated daily reference crop evapotranspiration (ETo) is normally used to determine the water requirement of crops using the crop factor method. Many ETo estimation methods have been developed for different types of climatic data, and the accuracy of these methods varies with climatic conditions. In this study, pair−wise comparisons were made between daily ETo estimated from eight different E...
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) ...
A brief history of development of the 1985 Hargreaves equation and its comparison to evapotranspiration ~ET! predicted by the Food and Agricultural Organization of the United Nations ~FAO! Penman-Monteith method are described to provide background and information helpful in selecting an appropriate reference ET equation under various data situations. Early efforts in irrigation water requiremen...
in agricultural practices, reference evapotranspiration (et0) parameters need to be specified for crop water requirement determination. although, the crop water requirement is not an easy task. numerous mathematical models and experimental methods have been developed for this purpose in the entire world. on the other hand, ten-daily and monthly average meteorological data are used in many of ir...
As a key hydrological parameter, daily reference evapotranspiration (ETo) determines the accuracy of the hydrological number of the crop, and, consequently, the regional optimization disposition of water resources. At present, the main methods for ETo estimation are the Penman-Monteith (PM) equation and its modified formula, both of which are based on climatic factors such as temperature, radia...
The Penman-Monteith equation is useful for computing evaporation rates of uniform surfaces, such as dense vegetation or bare soil. This equation becomes less useful for evaluation of evaporation rates at the regional scale, where surfaces are generally characterized by a patchy combination of vegetation and soil. This is particularly true in the arid and semi-arid regions of the world. The appr...
The recommended Penman±Monteith reference crop evapotranspiration (ET0) with derived crop coef®cients (Kc) from the phenomenological stages of Acala cotton is used to estimate the crop water requirements (CWRs) of Acala cotton in the Gezira area of Sudan. The published basal crop factors of Acala cotton were used with Penman±Monteith equation as well to estimate ET. The results were compared wi...
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