Coupling antecedent rainfall for improving the performance of rainfall thresholds for suspended sediment simulation of semiarid catchments.

Suspended sediment transport is one of the essential processes in the geochemical cycle. This study investigated the role of rainfall thresholds in suspended sediment modeling in semiarid catchments. The results showed that rainfall-sediment in the study catchment (HMTC) could be grouped into two patterns on the basis of rainfall threshold 10 mm. The sediment modeling based on LSTM model with the rainfall threshold (C-LSTM scheme) and without threshold (LSTM scheme) were evaluated and compared. The results showed that the C-LSTM scheme had much better performances than LSTM scheme, especially for the low sediment conditions. It was observed that in the study catchment, the mean NSE was marginally improved from 0.925 to 0.934 for calibration and 0.911 to 0.924 for validation for medium and high sediment (Pattern 1); while for low sediment (Pattern 2), the mean NSE was significantly improved from -0.375 to 0.738 for calibration and 0.171 to 0.797 for validation. Results of this study indicated rainfall thresholds were very effective in improving suspended sediment simulation. It was suggested that the incorporation of more information such as rainfall intensity, land use, and land cover may lead to further improvement of sediment prediction in the future.