Variations of Fluvial Sediment Transport after Large Earthquakes: Field Study in Taiwan Catchments

By estimating long-term suspended sediment discharges around river catchments, recovery periods of fluvial sediment transport after a large earthquake can be assessed. This study proved that the recovery period in a given catchment is positively correlated with the peak ground motions triggered by an earthquake. The correlation indicates that a recovery period of more than four years is required if a catchment is affected by an earthquake with a ground acceleration greater than 400 gal (~0.4 g). A total of four factors (sediment transport, seismic frequency, rock strength, and joint density) in the multivariate analysis were carefully considered to assess their influence on the sediment yield. As expected, runoff and geomaterial properties were the most important factors affecting the amount of suspended sediment discharges. The analysis of the influence factors further revealed that earthquake frequency is another important factor for sediment yield, especially within a few years after a large earthquake.