A Novel Evidential Uncertainty Framework for Hybrid Models in Rainfall Simulation
摘要
Reliable rainfall forecasting remains essential for effective water resources management and flood risk mitigation. This study develops two hybrid deep learning frameworks: a Convolutional Neural Network combined with Q-learning (CNN–Q-learning) and a Convolutional Neural Network–Long Short-Term Memory (CNN–LSTM) to simulate multi-station precipitation across Iran’s Karkheh Basin. Among the first, Evidential Deep Learning (EDL) is embedded into these hybrid models to analytically disentangle aleatoric (data-related) and epistemic (model-related) uncertainties within a single-pass predictive framework. Monthly precipitation data (1966–2019) from five synoptic stations were quality-controlled, normalized via Min–Max scaling, and used to train the models under a strict chronological split. To assess robustness and sampling uncertainty, bootstrap resampling and Latin Hypercube Sampling (LHS) were employed to generate ensemble scenarios and confidence intervals. The results demonstrate that CNN–Q-learning more effectively captures extreme precipitation and heavy-tailed distributions (Mean RMSE ≈ 1.7 mm; NSE ≈ 0.78; CRPS ≈ 0.65; KS ≈ 0.055), while CNN–LSTM yields sharper central predictions with slightly higher overall accuracy (Mean RMSE ≈ 1.1 mm; NSE ≈ 0.79; CRPS ≈ 0.91). EDL-derived uncertainty components indicate normalized aleatoric and epistemic variances, confirming the model’s ability to quantify both measurement and model uncertainty. Both models achieved full coverage of observations within 95% confidence bounds; however, CNN–Q-learning showed better calibration in the tails, while CNN–LSTM exhibited narrower predictive intervals. Overall, integrating EDL-based uncertainty quantification with an adaptive Q-learning policy provides a transparent, interpretable, and decision-oriented framework for probabilistic rainfall simulation. The CNN–Q-learning model is more suitable for risk management and extreme-event forecasting, whereas CNN–LSTM offers higher precision for routine operational predictions.