Seismic constraints on sediment budget for a mountainous catchment

In the steep mountain catchment, measuring the budget change of soil and sediment has always been a great challenge. Results of recent research have shown that the seismic station nearby river channels can capture seismic signals cause by different mechanisms such as water flow, sediment transport, and debris flow. Among them, river sediment transport and the debris flow have a more serious impact on the sediment mass distribution of river bed. This study site selected the Putanpunuas River in southern Taiwan where landslide occurred frequently, which could provide a stable source of sediment materials for this river. The temporals changes of erosion and deposition in the downstream alluvial fan can represent the income and expenditure of soil and sediment in the catchment area. Therefore, two broadband stations and one Geophone station were installed at downstream of the Putanpunuas River, and a broadband station was installed at the confluence of the Putanpunuas River and the Laonong River, which was named the Putanpunuas seismic array (PSA). By using a multi-temporal digital elevation model (DEM) of downstream alluvial fan, water level information captured by time-lapse images, time-frequency analysis of seismic signals, and the seismic physical models for different mechanisms (turbulent flow, bed saltation, debris flow), out study not only effectively monitor sediment transport but also provide better understanding on sediment budget in the catchment area. Temporal changes in erosion and deposition volume of the downstream alluvial fan was used to validate above seismology-based results.