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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhessd-3-1113-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
05 Feb 2015
Review status
This discussion paper has been under review for the journal Natural Hazards and Earth System Sciences (NHESS). The revised manuscript was not accepted.
Modelling of the hydrological connectivity changes in the Minjiang Upstream after the Wenchuan earthquake using satellite remote sensing and DEM data
H. Z. Zhang1,2,3, T. H. Chi1, and J. R. Fan2 1Institute of Remote Sensing and Digital Earth, Chines Academy of Sciences, Beijing, 100101, China
2Institute of Mountain Hazards and Environment, Chines Academy of Sciences, Chengdu, 610041, China
3University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100049, China
Abstract. The 2008 Wenchuan earthquake-induced landslides destroyed larger areas of mountain vegetation and produced large volume of landslide-debris, which made the vegetation's hydrological adjusting function diminished and made the hydrological progresses in slopes changed, resulting in severe erosion and catastrophic debris flows for a rather long time. Since 2008, the landslide-damaged vegetation and its hydrological function have been recovering. In this paper, the Minjiang Upstream watersheds around Yingxiu Town were selected. First, the landslide-damaged vegetation was identified and monitored via multi-temporal (2001–2014) satellite images. Then, the slope materials stability was assessed through topographic analysis of the vegetation survival environments. Then, the hydrological connectivity index (HCI) was defined to describe the upstream sediment production and downstream transport pathway. Finally, results indicated that HCI decreased annually with the vegetation recovery after the obvious increases during the earthquakes. While, analysis of 2008–2013 debris flow events indicated that the areas, the vertical drop to river <1000 m and the horizontal distance to river <2500 m, have high HCI increases and are more susceptible for debris flow formation. Monitoring the landslide-damaged vegetation recovery processes can contribute to assess the hydrological connectivity changes and understand the debris flow formation.

Citation: Zhang, H. Z., Chi, T. H., and Fan, J. R.: Modelling of the hydrological connectivity changes in the Minjiang Upstream after the Wenchuan earthquake using satellite remote sensing and DEM data, Nat. Hazards Earth Syst. Sci. Discuss., 3, 1113-1136, https://doi.org/10.5194/nhessd-3-1113-2015, 2015.
H. Z. Zhang et al.
H. Z. Zhang et al.

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Short summary
We model hydrological connectivity index (HCI) to detect the hydrologic processes changes with the landslide-damaged vegetation recovery in the Wenchuan earthquake-affected area, and the HCI results indicated that HCI obviously increased after the earthquake, and HCI decreased annually with the vegetation recovery. We consider that the lowest rainfall intensity and rainfall amount for debris flow initiation would rise up annually with HCI decreases and vegetation recovery.
We model hydrological connectivity index (HCI) to detect the hydrologic processes changes with...
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