Shoukat Ali Shah
Abstract
Reference Evapotranspiration (ETo) counted as the main factor for assessing the amount of water, needed for crops as well as for the planning of water resources management. Several techniques, methods, and equations have been used for computing ETo. Thus, required weather data sets are the main challenge ...
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Reference Evapotranspiration (ETo) counted as the main factor for assessing the amount of water, needed for crops as well as for the planning of water resources management. Several techniques, methods, and equations have been used for computing ETo. Thus, required weather data sets are the main challenge for evaluating this factor. FAO Penman-Monteith is the most popular technique to determine the ETo. The FAO 56-PM equation requires accurate weather data like air temperature, humidity, solar radiations, and wind speed. Unfortunately, not all these data are possible to reach easily on the station's side. Therefore, FAO 56 recommended another equation namely Hargreaves-Samani (HS) equation when sufficient weather data may not be available to estimate ETo by FAO56-PM. In the context of this, this study aimed to estimate ETo using the HS equation. For this purpose, historical annual, seasonal, and monthly temperature and wind data were collected from 1981 to 2020 using ‘The Prediction of Worldwide Energy Resources (POWER)’ web portal. It is concluded that the HS method in conjunction with the POWER datasets and spatially mapping with IDW interpolation gave reliable and accurate results of ETo. This technique gives an idea of water losses in a district and demonstrates a trend of historical annual, seasonal, and monthly ETo.
Ehsan Fadaei Kermani; Gholam Abbas Barani; Mohamad Javad Khanjani
Volume 1, Issue 2 , June 2014, , Pages 66-73
Abstract
In this paper, a new framework has been developed for compatibility analysis of predictive climatic variables distribution with reference evapotranspiration (ETo) in probabilistic analysis of water requirement. Initially, measured monthly meteorological data of four cities of Iran including Kerman, Shiraz, ...
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In this paper, a new framework has been developed for compatibility analysis of predictive climatic variables distribution with reference evapotranspiration (ETo) in probabilistic analysis of water requirement. Initially, measured monthly meteorological data of four cities of Iran including Kerman, Shiraz, Ramsar and Babolsar synoptic weather station recorded from 1961 to 2003 were considered based on De Martonne climate classification. Then monthly ETo was calculated using FAO-Penman-Moentith (FAO-PM), and optimum Probability distribution function (PDF) was determined. The Chow method has been used for frequency analysis, and compatibility analysis was implemented on results. Based on the results, the Generalized Pareto (GP) was selected as optimum PDF for ETo. Results showed that the optimum PDF for minimum and maximum temperature, solar radiation and relative humidity is GP which had compatibility with EToPDF. Eventually, obtained results in compatibility analysis framework were confirmed using Correlation analysis. The proposed methodology developed in this research has application capability in probability scheduling of design water requirement, and can be utilized to optimize probability estimate of water requirement.
