An Approach for Estimation of Evapotranspiration by Standardizing Parsimonious Method
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FULL-LENGTH RESEARCH ARTICLE
An Approach for Estimation of Evapotranspiration by Standardizing Parsimonious Method Nikul Kumari1 • Ankur Srivastava1
Received: 5 May 2019 / Accepted: 5 November 2019 Ó NAAS (National Academy of Agricultural Sciences) 2019
Abstract Evapotranspiration (ET) is one of the important components of the hydrological cycle which is essential for sustainable water resource management and ecohydrological studies. Accurate estimation of ET is a crucial task in datascarce regions due to limited meteorological variables. There exist a number of indirect methods among which the standard method for computing ET is FAO-56-Penman–Monteith (PM) method. However, due to paucity of flux data such as the components of net radiation, relative humidity, vapour pressure, and wind speed in many parts of the world, the use of standard benchmark method is limited. This limitation provides the widespread acceptance of the method which uses fewer variables and can give an accurate estimation of ET for water resource management. In this study, we have developed a framework to standardize the Hargreaves-based ET in the Kangsabati River basin. We utilize the weather datasets from six stations, namely Purulia, Bankura, Mohanpur, Jhargram, Kharagpur, and Midnapore to apply the ET standardization method. We have compared both the raw and corrected ET from Hargreaves with FAO-56-PM ET prior and after correction by using harmonization method. Performance evaluation of harmonization technique is done using statistical and graphical indicators for the duration of 2006–2010. It is observed that Purulia (r = 0.83 and d = 0.80) and Mohanpur (r = 0.85 and d = 0.87) stations are almost standardized appropriately on daily scale. Further, the highest r and R2 was obtained for Mohanpur station (r = 0.972; d = 0.940), while least for Jhargram station (r = 0.961; d = 0.741) at monthly scale. Overall, this approach can be used to provide the utility in data-scarce conditions irrespective of agro-climatic conditions. Keywords Evapotranspiration FAO-56-PM Penman–Monteith equation Hargreaves Data-scarce Harmonization
Introduction Evapotranspiration (ET) is the most significant variable in the global hydrological cycle as it one of the significant losses which take place in the surface energy budget [16]. Accurate estimates of ET are essential for crop modelling, hydrological modelling, climate studies, and agriculture management from regional to global scales [1, 13]. Though there are several methods in the literature which are used to & Ankur Srivastava [email protected] 1
School of Engineering, The University of Newcastle, Callaghan, NSW 2308, Australia
estimate ET, however, for data-scarce regions there is a need to provide a framework to standardize ET with the benchmark method FAO-56-PM. This will provide a basis in different climatologies to use this framework for estimation of ET with parsimonious datasets [20]. The reference ET is estimated about a standard (alfalfa) grass surface, 12 cm in average height
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