Status: this discussion paper is a preprint. It has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The manuscript was not accepted for further review after discussion.
A Hydrologically Based Model for Delineating Hazard Zones in the Valleys of Debris Flow Basins
Kaiheng Hu,Pu Li,Yong You,and Fenghuan Su
Abstract. A hydrologically based model is developed for delineating hazard zones in valleys of debris flow basins. The basic assumption of this model is that the ratio of peak discharges of any two cross sections in a debris-flow basin is a power function of the ratio of their flow accumulation areas. Combining the advantages of the empirical and flow routing models of debris-flow hazard zoning, this hydrological model with minimal data requirements has the ability to produce hazard intensity values at different event magnitudes. The algorithms used in this model are designed in the framework of grid- based geographic processing and implemented completely on ArcGIS platform and a Python scripting environment. Qipan basin in the Wenchuan county of Sichuan province, southwest China where a large-scale debris-flow event occurred on July 11, 2013 was chosen as the test case for the model. The hazard zone identified by the model showed good agreement with the real inundation area of the event. The proposed method can help identify small hazard areas in upstream tributaries and the developed model is promising in terms of its application in debris-flow hazard zoning.
Received: 14 Jan 2016 – Discussion started: 19 Jan 2016
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The region inundated by a debris-flow event in valleys of a basin depends on its peak discharge and channel topography. The larger the discharge is, the bigger the inundation area is. If we know the discharge at each cross section of the main channel, it can delineate the area reached by debris flow on the both sides of the channel. But, in most cases we can only get the discharge at one downstream section. So, an assumption is made to calculate the discharge at any section from a known section.
The region inundated by a debris-flow event in valleys of a basin depends on its peak discharge...
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