Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 18, 1395-1409, 2018
https://doi.org/10.5194/nhess-18-1395-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
17 May 2018
Rainfall threshold calculation for debris flow early warning in areas with scarcity of data
Hua-Li Pan1,2, Yuan-Jun Jiang1,2, Jun Wang3, and Guo-Qiang Ou1,2 1Key Laboratory of Mountain Hazards and Earth Surface Process, Chinese Academy of Sciences, Chengdu 610041, China
2Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
3Guangzhou Institute of Geography, Guangzhou 510070, China
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.
Citation: Pan, H.-L., Jiang, Y.-J., Wang, J., and Ou, G.-Q.: Rainfall threshold calculation for debris flow early warning in areas with scarcity of data, Nat. Hazards Earth Syst. Sci., 18, 1395-1409, https://doi.org/10.5194/nhess-18-1395-2018, 2018.
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Short summary
Debris flow early warning has always been based on well-calibrated rainfall thresholds. For areas where historical data are insufficient, to determine a rainfall threshold, it is necessary to develop a method to obtain the threshold by using limited data. A quantitative method, a new way to calculate the rainfall threshold, is developed in this study, which combines the initiation mechanism of hydraulic-driven debris flow with the runoff yield and concentration laws of the watershed.
Debris flow early warning has always been based on well-calibrated rainfall thresholds. For...
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