Modeling the sediment yield from landslides in the Shihmen Reservoir watershed, Taiwan

Abstract

Landslides generate enormous volumes of sediment in mountainous watersheds; however, quantifying the downstream transport of landslide‐derived sediment remains a challenge. Landslide erosion and sediment delivery to the Shihmen Reservoir watershed in Taiwan was estimated using empirical landslide frequency–area and volume–area relationships, empirical landslide runout models, and the Hydrological Simulation Program‐ FORTRAN (HSPF). Landslide erosion rates ranged from 0.4 mm yr‐1 to 2.2 mm yr‐1 during the period 1986–2003, but increased to 7.9 mm yr‐1 following Typhoon Aere in 2004. The percentage of landslide sediment delivered to streams decreased from 78% during the period 1986–1997 to 55% in 2004. Although the delivery ratio was lower, the volume of landslide sediment delivered to streams was 2.81 × 106 Mg yr‐1 in 1986–1997 and 8.60 × 106 Mg yr‐1 in 2004. Model simulations indicate that only a small proportion of the landslide material was delivered downstream. An average of 13% of the landslide material delivered to rivers was moved downstream during the period 1986–1997. In 2004, the period including Typhoon Aere, the annual fluvial sediment yield accounted for approximately 23% of the landslide material delivered to streams. In general, the transfer of sediment in the fluvial system in the Shihmen Reservoir watershed is dominantly transport limited. The imbalance between sediment supply and transport capacity has resulted in a considerable quantity of landslide material remaining in the upper‐stream regions of the watershed. Copyright © 2012 John Wiley & Sons, Ltd.

Connectivity of earthquake‐triggered landslides with the fluvial network: Implications for landslide sediment transport after the 2008 Wenchuan earthquake

“…This landslide-channel connectivity sets an initial condition for post-Wenchuan sediment transport. Channel-connected landslides are expected to have high potential for fluvial evacuation in the monsoonal climate [Liu-Zeng et al, 2011;Wang et al, 2015], whereas landslide material in the hillslope domain should be less immediately available for river transport [Meunier et al, 2008;Dadson et al, 2004;Hovius et al, 2011;Huang and Fan, 2013;Tsai et al, 2013]. These predictions can be tested by evaluating relationships between postearthquake sediment fluxes and the landslide inventory.…”

“…Several studies have quantified sediment mass flux and the associated residence times of landslide material in mountain belts using hydrological gauging data [ Pearce and Watson , ; Dadson et al ., ; Korup et al ., ; Hovius et al ., ; Tsai et al ., ; Wang et al ., ], topographic surveys of individual rivers [ Liu et al ., ; Yanites et al ., ], and geochemical measurements such as cosmogenic nuclide inventories [ West et al ., ; McPhillips et al ., ]. Other studies have used numerical models to predict the entrainment, transport, and deposition of sediment and to predict evacuation rates [e.g., Attal and Lavé , ; Cui et al ., ; Sutherland et al ., ; Ferguson et al ., ].…”

“…In contrast, transport of the coarser fraction (which makes up >90% of the total landslide volume) may be more significantly affected by landslide locations. Hovius et al, 2011;Tsai et al, 2013;Wang et al, 2015], topographic surveys of individual rivers [Liu et al, 2015;Yanites et al, 2010], and geochemical measurements such as cosmogenic nuclide inventories [West et al, 2014; McPhillips et al, 2014]. Other studies have used numerical models to predict the entrainment, LI ET AL.…”

How sample size can effect landslide size distribution

“…3 shows that 6,000 is a roughly safe choice for most landslide datasets. In view of this standard, utilizations of the parameters estimated based on small sample size, for example less than 1,000 (Fiorucci et al 2011;Ghosh et al 2012;Regmi et al 2014), especially for quantitative use (Larsen and Montgomery 2012;Tsai et al 2013), should be cautious. We will specifically inspect how sample size affects the reliability of landslide erosion estimates in the discussion.…”

Dynamic Modeling of Sediment Budget in Shihmen Reservoir Watershed in Taiwan

“…Then, huge amount of high concentration runoff flowed to the reservoir, causing sediment silting in a volume of approximately 2.7 × 10 7 m 3 [40]. After this typhoon, significant quantity of sediment that remained in upstream rivers [41] was continuously transported into the reservoir by subsequent rainfall, and considerably raised the turbidity of Shihmen Reservoir. Since then, the reservoir authority has been working on resolving the sediment problem through various countermeasures in the past decade (e.g., [8,41]).…”