The optimal alternative for quantifying reference evapotranspiration in climatic sub-regions of Bangladesh

Roquia Salam; Abu Reza Md Towfiqul Islam; Quoc Bao Pham; Majid Dehghani; Nadhir Al-Ansari; Nguyen Thi Thuy Linh

doi:10.1038/s41598-020-77183-y

The optimal alternative for quantifying reference evapotranspiration in climatic sub-regions of Bangladesh

Sci Rep. 2020 Nov 19;10(1):20171. doi: 10.1038/s41598-020-77183-y.

Authors

Roquia Salam¹, Abu Reza Md Towfiqul Islam¹, Quoc Bao Pham^{2

3}, Majid Dehghani⁴, Nadhir Al-Ansari⁵, Nguyen Thi Thuy Linh^{6

7}

Affiliations

¹ Department of Disaster Management, Begum Rokeya University, Rangpur, 5400, Bangladesh.
² Environmental Quality, Atmospheric Science and Climate Change Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
³ Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
⁴ Civil Engineering Department, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran.
⁵ Department of Civil, Environmental and Natural Resources Engineering, Lulea University of Technology, 97187, Lulea, Sweden.
⁶ Institute of Research and Development, Duy Tan University, Danang, 550000, Vietnam. nguyentthuylinh58@duytan.edu.vn.
⁷ Faculty of Environmental and Chemical Engineering, Duy Tan University, Danang, 550000, Vietnam. nguyentthuylinh58@duytan.edu.vn.

Abstract

Reference evapotranspiration (ET_o) is a basic element for hydrological designing and agricultural water resources management. The FAO56 recommended Penman-Monteith (FAO56-PM) formula recognized worldwide as the robust and standard model for calculating ET_o. However, the use of the FAO56-PM model is restricted in some data-scarce regions like Bangladesh. Therefore, it is imperative to find an optimal alternative for estimating ET_o against FAO56-PM model. This study comprehensively compared the performance of 13 empirical models (Hargreaves-Samani, HargreavesM1, Hargreaves M2, Berti, WMO, Abtew, Irmak 1, Irmak 2, Makkink, Priestley-Taylor, Jensen-Haise, Tabari and Turc) by using statistical criteria for 38-years dataset from 1980 to 2017 in Bangladesh. The radiation-based model proposed by Abtew (ET_o,6) was selected as an optimal alternative in all the sub-regions and whole Bangladesh against FAO56-PM model owing to its high accuracy, reliability in outlining substantial spatiotemporal variations of ET_o, with very well linearly correlation with the FAO56-PM and the least errors. The importance degree analysis of 13 models based on the random forest (RF) also depicted that Abtew (ET_o,6) is the most reliable and robust model for ET_o computation in different sub-regions. Validation of the optimal alternative produced the largest correlation coefficient of 0.989 between ET_o,s and ET_o,6 and confirmed that Abtew (ET_o,6) is the best suitable method for ET_o calculation in Bangladesh.