Variability in rainfall threshold for debris flow after Wenchuan earthquake in Gaochuan River watershed, Southwest China

2016 ◽  
Vol 82 (3) ◽  
pp. 1967-1980 ◽  
Author(s):  
Tian-Tao Li ◽  
Run-Qiu Huang ◽  
Xiang-Jun Pei
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Southwest China ◽  
Rainfall Threshold ◽  
River Watershed

Spatial-Temporal Assessment of Debris Flow Risk in the Ms8.0 Wenchuan Earthquake-Disturbed Area

2016 ◽  
Vol 11 (4) ◽  
pp. 720-731 ◽  
Author(s):  
Xin Yao ◽  
◽  
Lingjing Li ◽  
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Early Warning Systems ◽  
Rainfall Threshold ◽  
Significant Loss ◽  
Seismogenic Fault ◽  
Mountain Area ◽  
Disturbed Area ◽  
Geological Conditions

For 5 years (2009–2013) after the 2008 Ms8.0 Wenchuan earthquake, rainfall led to the transformation of unconsolidated co-seismic deposits into extensive and severe debris flows, causing significant loss of life and property. For debris flows in the earthquake-disturbed area, a few common concerns exist. What is their spatial-temporal distribution? What are the controlling factors? How much is the rainfall threshold for debris flows? What areas are more susceptible? Where suffered the most severe losses of life and property? Using debris flow characteristics, this study analyzes the relationships between seismic geological factors, geomorphologic factors, extreme rainfall, and debris flows in the 5 years following the earthquake, and draws the following conclusions. (1) There are regional differences in the rainfall threshold for generation of debris flows, and the annual maximum 72-hour accumulated rainfall for triggering a debris flow decreases from pre-seismic periods (135–325 mm) to post-seismic periods (75–160 mm) by 44.4–50.8% in study area. (2) Areas with high debris flow susceptibility and hazard are primarily controlled by seismic geological conditions. (3) The long-term risk of debris flows will fall to moderate, and the affected area will shrink to that around the seismogenic fault. The results of this study will help with meteorological early warning systems, deployment of disaster prevention and control projects, and reconstruction site selection in the post-seismic Longmen Mountain area.

scholarly journals Rainfall threshold calculation for debris flow early warning in areas with scarcity of data

2018 ◽  
Vol 18 (5) ◽  
pp. 1395-1409 ◽  
Author(s):  
Hua-Li Pan ◽  
Yuan-Jun Jiang ◽  
Jun Wang ◽  
Guo-Qiang Ou
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Early Warning ◽  
Debris Flows ◽  
Early Warning Systems ◽  
Rainfall Threshold ◽  
Warning Systems ◽  
Mountainous Areas ◽  
Rainfall Thresholds ◽  
Initiation Mechanism

Abstract. Debris flows are natural disasters that frequently occur in mountainous areas, usually accompanied by serious loss of lives and properties. One of the most commonly used approaches to mitigate the risk associated with debris flows is the implementation of early warning systems based on well-calibrated rainfall thresholds. However, many mountainous areas have little data regarding rainfall and hazards, especially in debris-flow-forming regions. Therefore, the traditional statistical analysis method that determines the empirical relationship between rainstorms and debris flow events cannot be effectively used to calculate reliable rainfall thresholds in these areas. After the severe Wenchuan earthquake, there were plenty of deposits deposited in the gullies, which resulted in several debris flow events. The triggering rainfall threshold has decreased obviously. To get a reliable and accurate rainfall threshold and improve the accuracy of debris flow early warning, this paper developed a quantitative method, which is suitable for debris flow triggering mechanisms in meizoseismal areas, to identify rainfall threshold for debris flow early warning in areas with a scarcity of data based on the initiation mechanism of hydraulic-driven debris flow. First, we studied the characteristics of the study area, including meteorology, hydrology, topography and physical characteristics of the loose solid materials. Then, the rainfall threshold was calculated by the initiation mechanism of the hydraulic debris flow. The comparison with other models and with alternate configurations demonstrates that the proposed rainfall threshold curve is a function of the antecedent precipitation index (API) and 1 h rainfall. To test the proposed method, we selected the Guojuanyan gully, a typical debris flow valley that during the 2008–2013 period experienced several debris flow events, located in the meizoseismal areas of the Wenchuan earthquake, as a case study. The comparison with other threshold models and configurations shows that the selected approach is the most promising starting point for further studies on debris flow early warning systems in areas with a scarcity of data.

Susceptibility Assessments and Validations of Debris-Flow Events in Meizoseismal Areas: Case Study in China’s Longxi River Watershed

2020 ◽  
Vol 21 (1) ◽  
pp. 05019005 ◽  
Author(s):  
Saier Wu ◽  
Jian Chen ◽  
Chong Xu ◽  
Wendy Zhou ◽  
Leihua Yao ◽  
...  
Keyword(s):  
Debris Flow ◽  
River Watershed

scholarly journals Application and analysis of debris-flow early warning system in Wenchuan earthquake-affected area

2016 ◽  
Vol 16 (2) ◽  
pp. 483-496 ◽  
Author(s):  
D. L. Liu ◽  
S. J. Zhang ◽  
H. J. Yang ◽  
L. Q. Zhao ◽  
Y. H. Jiang ◽  
...  
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Early Warning ◽  
Early Warning System ◽  
Prediction Accuracy ◽  
Warning System ◽  
Sichuan Province ◽  
Affected Area ◽  
The Wenchuan Earthquake ◽  
New System

Abstract. The activities of debris flow (DF) in the Wenchuan earthquake-affected area significantly increased after the earthquake on 12 May 2008. The safety of the lives and property of local people is threatened by DFs. A physics-based early warning system (EWS) for DF forecasting was developed and applied in this earthquake area. This paper introduces an application of the system in the Wenchuan earthquake-affected area and analyzes the prediction results via a comparison to the DF events triggered by the strong rainfall events reported by the local government. The prediction accuracy and efficiency was first compared with a contribution-factor-based system currently used by the weather bureau of Sichuan province. The storm on 17 August 2012 was used as a case study for this comparison. The comparison shows that the false negative rate and false positive rate of the new system is, respectively, 19 and 21 % lower than the system based on the contribution factors. Consequently, the prediction accuracy is obviously higher than the system based on the contribution factors with a higher operational efficiency. On the invitation of the weather bureau of Sichuan province, the authors upgraded their prediction system of DF by using this new system before the monsoon of Wenchuan earthquake-affected area in 2013. Two prediction cases on 9 July 2013 and 10 July 2014 were chosen to further demonstrate that the new EWS has high stability, efficiency, and prediction accuracy.

scholarly journals Analysis of a debris flow after Wenchuan Earthquake and discussion on preventive measures

2019 ◽  
Vol 23 (3 Part A) ◽  
pp. 1563-1570
Author(s):  
Zhi-Long Zhang ◽  
Jing Xie ◽  
De-Ke Yu ◽  
Zhi-Jie Wen
Keyword(s):  
Debris Flow ◽  
Wenchuan Earthquake ◽  
Preventive Measures ◽  
Impact Force ◽  
Site Investigation ◽  
The Wenchuan Earthquake ◽  
Formation Conditions ◽  
National Road ◽  
And Control ◽  
Debris Flow Disaster

This paper addresses a debris flow disaster in Yingxiu town after the Wenchuan earthquake. Through site investigation and data review, the geography and geological environment of the basin and the development, formation conditions and activity characteristics of the debris flow in the basin are analyzed. Calculate and analyze the characteristics of the debris flow, such as gravity, flow velocity and impact force. According to the management idea of combination of blocking and discharging, this paper proposes to arrange three blocking dams in the main ditch, construct drainage gullies in the downstream accumulation section, and prevent and control the aqueduct in the intersection of the main ditch and the G213 national road, which will be similar to the earthquake in the future. It is provided as a reference for research and prevention of the debris flow.

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