An integrated framework for real-time river sediment monitoring: fusing low-cost hydrometry with a comparison of LSTM and N-BEATS models and uncertainty analysis

Document Type : Original Article

Authors

1 Department of Water Resources Engineering, Faculty of Civil, Water and Environmental Engineering , Shahid Beheshti University, Tehran, Iran.

2 Department of Water Resources Engineering, Faculty of Civil , Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

Abstract

Objective: The objective of this study was to develop an integrated framework for real-time monitoring and prediction of the median bed-sediment diameter (D50) in rivers and to compare the performance of two deep learning architectures, Long Short-Term Memory (LSTM) and Neural Basis Expansion Analysis for Time Series (N-BEATS), in predicting sediment size. An additional objective was to quantify the uncertainty of LSTM predictions using Monte Carlo (MC) dropout.
 
Method: High-frequency water-level time-series data were collected from the Roudak River in Tehran using a custom-designed, low-cost ultrasonic stage sensor. The water-level data were integrated with grain-size analysis results obtained from bed-sediment samples collected during multiple field campaigns. Two deep learning models, LSTM and N-BEATS, were developed and evaluated for predicting D50. In addition, Monte Carlo dropout was applied to the LSTM model to assess the uncertainty and confidence of its predictions.
 
Results: Both deep learning models demonstrated a strong capability to learn the complex relationships between river hydraulic conditions and bed-sediment characteristics. However, the N-BEATS model achieved superior predictive performance, with an R² of 0.871 and an RMSE of 0.054, compared with an R² of 0.861 and an RMSE of 0.056 for the LSTM model. These results indicate that N-BEATS provided more accurate and robust predictions of D50.
 
Conclusions: The study demonstrated that integrating low-cost real-time water-level monitoring with advanced deep learning techniques provides a practical and cost-effective approach for river sediment monitoring. The superior performance of N-BEATS compared with LSTM highlights the potential of modern time-series architectures for improving computational hydrology and supporting more effective sediment and water-resources management.

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