A novel integrated multicriteria decision analysis framework for group decision-making in evapotranspiration model selection

Accurate estimation of reference evapotranspiration (ETo) is essential for effective water resource management and agricultural planning, particularly in regions with diverse climatic conditions and data limitations. This study addresses the challenge of selecting suitable ETo models by evaluating 20 temperature-based, 20 radiation-based, and 11 mass transfer-based models in Nigeria using 53 years of ERA5 meteorological data (1950–2022), with the Penman–Monteith (PM) method as the reference. A novel integrated multicriteria decision analysis (MCDA) framework, termed group decision-making analysis (GDMA), was developed by combining three established MCDA techniques: Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), Vise Kriterijumsa Optimizacija I Kompromisno Resenje (VIKOR), and Weighted Aggregated Sum Product Assessment (WASPAS). This approach optimizes ETo model selection by harmonizing rankings across multiple criteria through a consensus-driven decision-making process. The results identified the World Meteorological Organization (WMO) model as the most suitable alternative to the PM method, achieving a KGE of 0.89, NSE of 0.97, PBIAS of 6.63%, and NRMSE of 17.27%, followed by the Penman model with a KGE of 0.74, NSE of 0.74, PBIAS of −10.17%, and NRMSE of 47.83%. The integrated GDMA framework effectively resolved discrepancies arising from different statistical metrics and MCDA methods, ensuring a robust and reliable model selection process. This study underscores the efficacy of the GDMA framework in selecting optimal ETo models, particularly in data-limited regions, and highlights its potential for application in other climatic zones. The findings provide valuable insights into improving irrigation planning, water resource management, and climate adaptation strategies in Nigeria and similar contexts.