EGU21-1691, updated on 28 Sep 2021 https://doi.org/10.5194/egusphere-egu21-1691 EGU General Assembly 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Bayesian Belief Networks for the metamodeling of simulation- optimization model to identify optimum water allocation scenario, Application in Miyandoab plain, Urmia Lake basin, Iran Amirhossein Dehghanipour1,2, Gerrit Schoups3, Hossein Babazadeh4, Majid Ehtiat5, and Bagher Zahabiyoun6 1Department of Water Management, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran ([email protected]) 2Present address: Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, Netherlands ([email protected]) 3Department of Water Management, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, Netherlands ([email protected]) 4Department of Water Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran ([email protected]) 5College of Engineering, Civil Engineering Group, Ardakan University, Yazd, Iran ([email protected]) 6Department of Water Management, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran ([email protected]) In this study, decision-making models in uncertain conditions are developed to identify optimal strategies for reducing competition between agricultural and environmental water demand. The decision-making models are applied to the irrigated Miyandoab Plain, located upstream of endorheic Lake Urmia in Northwestern Iran. Decision-making models are conceptualized based on static and dynamic Bayesian Belief Networks (BBN). The static BBN evaluates the effects of management strategies and drought conditions on environmental flow and agricultural profit at the annual scale, while the dynamic BBN accounts for monthly dynamics of water demand and conjunctive use. The reliability and performance of BBNs depend on the quantity and quality of data used to train the BBN and create conditional probability tables (CPTs). In this study, simulated outputs from a multi-period simulation-optimization model (Dehganipour et al., 2020) are used to populate the CPTs in each BBN and reduce the BBN training error. Cross-validation tests and sensitivity analysis are used to evaluate the effectiveness of the resulting BBNs. Sensitivity analysis shows that drought conditions have the most significant impact on environmental flow compared to other variables. Cross-validation tests show that the BBNs are able to reproduce outputs of the complex simulation-optimization model used for training, and therefore provide a computationally fast alternative for decision-making under uncertainty. Reference: Dehghanipour, A. H., Schoups, G., Zahabiyoun, B., & Babazadeh, H. (2020). Meeting agricultural and environmental water demand in endorheic irrigated river basins: A simulation- optimization approach applied to the Urmia Lake basin in Iran. Agricultural Water Management, 241, 106353. Powered by TCPDF (www.tcpdf.org).