A rationale for effective post-fire debris flow mitigation within forested terrain
A rationale for effective post-fire debris flow mitigation within forested terrain
复制标题
在森林地区有效缓解火后泥石流的理由
DOI：
10.1186/s40677-018-0099-z
复制
发表时间：
2018
影响因子：
4.8
通讯作者：
J. D. Graff
中科院分区：
文献类型：
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作者：
J. D. Graff
最近被野火烧毁的流域被认为对泥石流发生的敏感性增加。绝大多数发生在野火发生后的头两年内。这些泥石流主要是通过地表径流从山坡和渠道侵蚀的物质逐渐夹带的过程产生的，似乎独立于被烧毁的植物群落。随着时间的推移，泥石流的可能性降低，这与水文功能的恢复有关，因为植被和土壤渗透功能恢复到火灾前的状态。野火后泥石流易感性的这种模式的一个例外发生在被烧毁的流域森林覆盖。第二，后期增加泥石流的敏感性，由于渗透引发的滑坡可能会发生在燃烧的森林盆地。这后期的泥石流的易感性主要是由于火灾引起的树木死亡率和随后的树木根系网络衰减降低土壤强度陡峭的山坡上产生的泥石流发生的可能性增加3至10年或更长的野火后。因此，森林地带的灾后减灾措施必须处理野火发生后两年内逐渐卷吸造成的泥石流以及三年或三年以上后渗透引起的泥石流所造成的风险。森林地带后期泥石流的缓解措施涉及确定与火灾死亡树木集中一致的渗透引起的泥石流区域。野火过后，及时在这些地区重新造林，可以限制腐烂的树根造成的土壤强度损失。
Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2 years following wildfires. These debris flows are generated primarily through the process of progressive entrainment of material eroded from hillslopes and channels by surface runoff and appears independent of the vegetative community burned. The decreased likelihood of debris flows over time is linked to the restoration of hydrologic function as vegetative cover and soil infiltration functioning return to pre-fire conditions. An exception to this pattern of post-wildfire debris flow susceptibility occurs in burned drainage basins with forest cover. A second, later period of increased debris flow susceptibility due to infiltration-triggered landslides can occur in burned forested basins. This later period of debris flow susceptibility is largely attributable to the fire-induced tree mortality and subsequent decay of tree root networks decreasing soil strength on steep hillslopes which produces an increased likelihood of debris flow occurrence 3 to 10 or more years after the wildfire. Consequently, post-fire mitigation measures in forested terrain must address the risk posed by debris flows caused by progressive entrainment during the 2 years following the wildfire and debris flows due to infiltration-induced debris slides three or more years later. Mitigation for the later debris flows in forested terrain involves identification of areas with infiltration-induced debris slides coincident with concentrations of fire-killed trees. Timely reforestation of these areas after a wildfire limits the loss of soil strength from decaying roots.