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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Effect of storms during drought on post-wildfire recovery of channel sediment dynamics and habitat in the southern California chaparral, USA
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Effect of storms during drought on post-wildfire recovery of channel sediment dynamics and habitat in the southern California chaparral, USA

机译：干旱期间风暴对野战后群落沉积动力学和栖息地的影响 - 美国南部Chaparral

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Current global warming projections suggest a possible increase in wildfire and drought, augmenting the need to understand how drought following wildfire affects the recovery of stream channels in relation to sediment dynamics. We investigated post-wildfire geomorphic responses caused by storms during a prolonged drought following the 2013 Springs Fire in southern California (USA), using multi-temporal terrestrial laser scanning and detailed field measurements. After the fire, a dry-season dry-ravel sediment pulse contributed sand and small gravel to hillslope-channel margins in Big Sycamore Creek and its tributaries. A small storm in WY 2014 generated sufficient flow to mobilize a portion of the sediment derived from the dry-ravel pulse and deposited the fine sediment in the channel, totaling similar to 0.60m(3)/m of volume per unit length of channel. The sediment deposit buried step-pool habitat structure and reduced roughness by over 90%. These changes altered sediment transport characteristics of the bed material present before and after the storm; the ratio of available to critical shear stress (to/tc) increased by five times. Storms during WY 2015 contributed additional fine sediment from tributaries and lower hillslopes and hyperconcentrated flow transported and deposited additional sediment in the channel. Together these sources delivered sediment on the order of six times that in 2014, further increasing to/tc. These storms during multi-year drought following wildfire transformed channel dynamics. The increased sediment transport capacity persisted during the drought period characterized by the longer residence time of relatively fine-grained post-fire channel sedimentation. This contrasts with wetter years, when post-fire sediment is transported from the fluvial system during the same season as the post-fire sediment pulse. Results of this short-term study highlight the complex and substantial effects of multi-year drought on geomorphic responses following wildfire. These responses influence pool habitat that is critical to longer-term post-wildfire riparian ecosystem recovery. Copyright (C) 2017 John Wiley & Sons, Ltd.
机译：目前的全球变暖预测表明野火和干旱可能会增加，增强了解野火后干旱如何影响流频道的恢复，与沉积物动态相关。我们调查了在2013年春季南部（美国）的延长干旱期间暴风雨造成的野战后果响应，采用多时间陆地激光扫描和详细的现场测量。火灾发生后，干季干斗沉积物脉冲延迟沙子和小砾石到大梧桐溪的山坡通道边缘及其支流。 WY 2014中的一个小型风暴产生了足够的流量，以动员来自干斗脉冲的一部分沉积物并沉积通道中的细沉积物，总共相似的每单位长度的0.60m（3）/ m。沉积物沉积埋藏河流栖息地结构，减少粗糙度超过90％。这些变化改变了风暴前后存在的床材料的沉积物传输特性;可用于临界剪切应力（至/ Tc）的比率增加了五次。 2015年WY 2015期间的暴风雨从支流和下山坡上的额外细沉积物贡献了额外的细沉积物，并且在通道中运输并沉积额外的沉积物。这些来源将沉积物达到2014年的六次，进一步增加至/ TC。在野火转型渠道动态之后的多年干旱期间这些风暴。在干旱期间持续存在的沉积物运输能力增加，其特征在于，较长的火灾后沟道沉降的较长停留时间。当在同一季节从河水系统运输后火灾沉积物作为火灾后沉积物脉冲时，这种对比较潮湿的血液形成鲜明对比。该短期研究的结果突出了野火后几年干旱的复杂和大量影响。这些反应影响池栖息地，这对长期野战后河流生态系统恢复至关重要。版权所有（c）2017 John Wiley＆Sons，Ltd。

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