Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity
Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity
复制标题
逃生路线指数：荒地消防员逃生能力的空间明确测量
作者：
Michael J. Campbell;Wesley G. Page;P. Dennison;B. Butler
对于野外消防员来说，有效疏散火线的能力受到地形、植被和火灾条件的限制。地形和植被对疏散到安全区时间的影响可能不明显，当考虑到潜在的控制地点时，无论是在野火发生时还是在预灭火规划期间。为了满足对出口容量的空间明确度量的需求，本文引入了逃生路线指数（ERI）。ERI的范围从0到1，是在一个时间框架内行驶距离的标准化比率，考虑到坡度和植被的阻抗，在没有这些障碍的情况下行驶的最佳距离。ERI接近1表明地形和植被条件对消防员流动性的影响不大，而ERI接近0则代表有限的越野旅行流动性。疏散的方向性允许计算四个ERI指标：(1)ERImean（所有旅行方向的平均ERI）；(2) ERImin（最低出口方向的ERI）；(3) ERImax（最高出口方向的ERI）；(4) ERIazimuth （ERImax方向方位角）。我们在美国加利福尼亚州的安吉利斯国家森林演示了三种不同疏散时间框架（10,20和30分钟）的ERI实施。先前发表的坡度和旅行率之间的众包关系用于解释地形，而植被则通过基于野火决策支持系统（WFDSS）的因素使用土地覆盖来调整旅行率。土地覆被对ERI值的影响大于坡度。我们还模拟了最近几次野外消防员陷阱的ERI值，以评估景观条件可能对这些事件的影响程度，发现ERI值从队员撤离起点开始普遍较低。我们的结论是，在火灾发生前绘制ERI地图可以帮助消防员了解特定地点的整体风险，并有助于确定具有更大出口能力的地点，以便集中灭火，从而潜在地降低被困的风险。植被密度测绘精度的不断提高以及光探测和测距（激光雷达）的可用性的增加将极大地有利于未来ERI的实施。
For wildland firefighters, the ability to efficiently evacuate the fireline is limited by terrain, vegetation, and fire conditions. The impacts of terrain and vegetation on evacuation time to a safety zone may not be apparent when considering potential control locations either at the time of a wildfire or during pre-suppression planning. To address the need for a spatially-explicit measure of egress capacity, this paper introduces the Escape Route Index (ERI). Ranging from 0 to 1, ERI is a normalized ratio of the distance traveled within a time frame, accounting for impedance by slope and vegetation, to the optimal distance traveled in the absence of these impediments. An ERI approaching 1 indicates that terrain and vegetation conditions should have little impact on firefighter mobility while an ERI approaching 0 is representative of limited cross-country travel mobility. The directional nature of evacuation allows for the computation of four ERI metrics: (1) ERImean (average ERI in all travel directions); (2) ERImin (ERI in direction of lowest egress); (3) ERImax (ERI in direction of highest egress); and (4) ERIazimuth (azimuth of ERImax direction). We demonstrate the implementation of ERI for three different evacuation time frames (10, 20, and 30 min) on the Angeles National Forest in California, USA. A previously published, crowd-sourced relationship between slope and travel rate was used to account for terrain, while vegetation was accounted for by using land cover to adjust travel rates based on factors from the Wildland Fire Decision Support System (WFDSS). Land cover was found to have a stronger impact on ERI values than slope. We also modeled ERI values for several recent wildland firefighter entrapments to assess the degree to which landscape conditions may have contributed to these events, finding that ERI values were generally low from the crews’ evacuation starting points. We conclude that mapping ERI prior to engaging a fire could help inform overall firefighter risk for a given location and aid in identifying locations with greater egress capacity in which to focus wildland fire suppression, thus potentially reducing risk of entrapment. Continued improvements in accuracy of vegetation density mapping and increased availability of light detection and ranging (lidar) will greatly benefit future implementations of ERI.
影响因子：
4.9
作者：
Campbell, Michael J.;Dennison, Philip E.;Page, Wesley G.
通讯作者：
Page, Wesley G.