Applying ANN emulators in uncertainty assessment of flood inundation modelling: a comparison of two surrogate schemes |
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| Authors: | JJ Yu |
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| Institution: | 1. School of Civil &2. Environmental Engineering, Nanyang Technological University, Singapore, Singapore;3. DHI-NTU Water &4. Environment Research Centre and Education Hub, DHI Water &5. Environment (S) Pte. Ltd., Singapore, Singaporexsqin@ntu.edu.sg |
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| Abstract: | AbstractA generalized likelihood uncertainty estimation (GLUE) framework coupling with artificial neural network (ANN) models in two surrogate schemes (i.e. GAE-S1 and GAE-S2) was proposed to improve the efficiency of uncertainty assessment in flood inundation modelling. The GAE-S1 scheme was to construct an ANN to approximate the relationship between model likelihoods and uncertain parameters for facilitating sample acceptance/rejection instead of running the numerical model directly; thus, it could speed up the Monte Carlo simulation in stochastic sampling. The GAE-S2 scheme was to establish independent ANN models for water depth predictions to emulate the numerical models; it could facilitate efficient uncertainty analysis without additional model runs for locations concerned under various scenarios. The results from a study case showed that both GAE-S1 and GAE-S2 had comparable performances to GLUE in terms of estimation of posterior parameters, prediction intervals of water depth, and probabilistic inundation maps, but with reduced computational requirements. The results also revealed that GAE-S1 possessed a slightly better performance in accuracy (referencing to GLUE) than GAE-S2, but a lower flexibility in application. This study shed some light on how to apply different surrogate schemes in using numerical models for uncertainty assessment, and could help decision makers in choosing cost-effective ways of conducting flood risk analysis. |
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| Keywords: | GLUE artificial neural network surrogate uncertainty flood inundation |
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