Investigating sediment dynamics in a landslide-dominated catchment by modeling landslide area and fluvial sediment export
Journal
Water (Switzerland)
Journal Volume
12
Journal Issue
10
Pages
1-20
Date Issued
2020
Author(s)
Abstract
Few models are capable of simultaneously simulating the sequences of landslide occurrence and sediment export. Quantification of the temporarily stored sediment within the watershed plays a key role to link hillslope landslides with fluvial sediment export. In this study, two coupled models were proposed to simulate time-series total landslide area and the subsequent sediment export on a daily basis with only the inputs of rainfall and runoff. The landslide model considers per-existing and models new landslide, and the sediment transport model incorporates a sediment storage variable. The landslide and sediment transport model were well evaluated with Nash-Sutcliffe efficiency (EC) of 0.89 and logarithmic Nash-Sutcliffe efficiency (EClog ) of 0.90, respectively, in the Tsengwen Reservoir watershed in southern Taiwan by using long-term observed data (2005–2015). It is found that reactivated landslides were up to 72% of the pre-landslide area, which contributed sediment comparable to the new landslide. Besides, the landslide model indicates that pre-landslide area controls the total landslide area but when rainfall is large it takes control in turn. With the simulation of sediment storage, the sediment transport model can well simulate the sediment export after the catastrophic event (typhoon Morakot in 2009). During the post-Morakot period, small rainfall and runoff can lead to high sediment export owing to the storage of Morakot-triggered landslide. This model will be a useful tool to diagnose the sediment dynamics in the watershed. ? 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Subjects
Catchments; Digital storage; Efficiency; Rain; Runoff; Sediment transport; Sedimentation; Watersheds; Catastrophic event; Fluvial sediment; Hillslope landslides; Rainfall and runoffs; Sediment dynamic; Sediment exports; Sediment storage; Sediment transport model; Landslides; catastrophic event; catchment; fluvial deposit; hillslope; landslide; precipitation intensity; sediment transport; typhoon; watershed; Taiwan; Tsengwen Reservoir
Type
journal article