Interpretable Water Level Forecaster with Spatiotemporal Causal Attention Mechanisms

Forecasting the water level of the Han River is essential to control traffic and avoid natural disasters. The stream flow of the Han River is affected by various and intricately connected factors. Thus, a simple forecasting machine frequently fails to capture its serial pattern. On the other hand, a complex predictive model loses the interpretability of the model output. This work proposes a neural network model with a novel transformer exploiting a causal relationship based on prior knowledge. The transformer consists of spatiotemporal attention weight that describes the spatial and temporal causation with multilayer networks with masking. Our model has two distinguished advantages against the existing spatiotemporal forecasting models. First, the model allows the heterogeneous predictors for each site such that a flexible regression is applicable to the causal network. Next, the model is adapted to partially identified causal structures. As a result, we have relaxed the constraints of the applicable causal network through our model. In real data analysis, we use the Han River dataset from 2016 to 2021, compare the proposed model with deep learning models, and confirm that our model provides an interpretable and consistent model with prior knowledge, such as a seasonality arising from the tidal force. Furthermore, in prediction performance, our model is better than or competitive with the state-of-the-art models.