Using an integrated method to estimate watershed sediment yield during heavy rain period: a case study in Hualien County, Taiwan

Abstract

Abstract.A comprehensive approach estimating sediment yield from a watershed is needed to develop better measures for mitigating sediment disasters and assessing downstream impacts. In the present study, an attempt has been made to develop an integrated method, considering sediment supplies associated with soil erosion, shallow landslide and debris flow to estimate sediment yield from a debris-flow-prone watershed on a storm event basis. The integrated method is based on the HSPF and TRIGRS models for predicting soil erosion and shallow landslide sediment yield, and the FLO-2D model for calculating debris flow sediment yield. The proposed method was applied to potential debris-flow watersheds located in the Sioulin Township of Hualien County. The available data such as hourly rainfall data, historical streamflow and sediment records as well as event-based landslide inventory maps have been used for model calibration and validation. Results for simulating sediment yield have been confirmed by comparisons of observed data from several typhoon events. The verified method employed a 24-h design hyetograph with the 100-yr return period to simulate sediment yield within the study area. The results revealed that the influence of shallow landslides on sediment supply as compared with soil erosion was significant. The estimate of landslide transport capacity into a main channel indicated the sediment delivery ratio on a typhoon event basis was approximately 38.4 %. In addition, a comparison of sediment yields computed from occurrence and non-occurrence of debris flow scenarios showed that the sediment yield from an occurrence condition was found to be increasing at about 14.2 times more than estimated under a non-occurrence condition. This implied watershed sediment hazard induced by debris flow may cause severe consequences.

Characteristics of Suspended Sediment Loadings under Asian Summer Monsoon Climate Using the Hydrological Simulation Program-FORTRAN

“…Due to these difficulties, it is rare for a case study to calibrate and validate water quality using monitoring data for rainy days. Hsu et al [25] calibrated and validated stream flow and sediment loads of HSPF simulation using typhoon events. Many case studies in recent (in the last 5 years) research did not perform validation processes for the water quality simulation of HSPF because it is very hard to obtain monitoring data during the rainy season for validation process [26][27][28].…”

Potential Impact of Landslide and Debris Flow on Climate Extreme – A Case Study of Xindian Watershed in Taiwan

“…discussion. In this process, different physical mechanisms could be simulated by combination of different models (Chen et al, 2011;Hsu et al, 2012;Liu et al, 2013;Fan et al, 2017;Li et al, 2017) such as rainfall, landslide, debris flow, etc. The detail of each parts will be introduced in the following.…”

“…However, the theories of different physical 15 phenomena such as sediment production or transport process are discrepancy. Therefore, some researchers start to apply suitable numerical techniques in different physical phenomena, and combine them as a chain by linking a model output to the other model input (Chen et al, 2011;Hsu et al, 2012;Liu et al, 2013;Fan et al, 2017;Li et al, 2017). With integrated simulation, Chen et al (2011) has discussed the compound disaster including landslide, debris flow, small-scale floods in past real event.…”

“…Because the sediment production during a rainfall event is dominated by landslide mass (Hsu et al, 2012), the soil erosion on slope land is ignored in our discussion. Under extreme rainfall and loose landslide mass, we assume sediment will transport by debris flow from upstream catchment.…”

Modeling Typhoon‐Induced Alterations on River Sediment Transport and Turbidity Based on Dynamic Landslide Inventories: Gaoping River Basin, Taiwan

“…Since Li (1976) [2] reported a denudation rate claiming to be the highest in the world, issues related to hillslope erosion and sediment discharge in the Central Range of Taiwan have attracted widespread attention [3]. Many studies have been performed to estimate the erosion rate and sediment discharge [4], analyze factors controlling sediment removal and supply [5,6], identify the links between erosion, storm frequency and seismicity [7], and investigate the roles of lithology, episodic events (typhoons and earthquakes) and human activities on sediment discharge [3]. All show that frequent large earthquakes and typhoons triggered large numbers of landslides, which significantly modified the land cover patterns of mountain areas, resulting in high erosion rates and increased sediment fluxes to the ocean.…”