An Approach for Estimation of Evapotranspiration by Standardizing Parsimonious Method

摘要

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 data-scarce 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 R-2 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.