...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Volcanology and Geothermal Research >Calculation of lahar transit times using digital elevation data
【24h】

Calculation of lahar transit times using digital elevation data

机译：使用数字高程数据计算通行时间

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Volcanic debris flows, or lahars, represent a significant hazard because of their rapid emplacement, long runout distances, and tremendous destructive potential. Accurate knowledge of advance rates and flow depths is therefore critical to hazard mitigation in lahar-prone areas. With the increasing availability of digital topographic data, models of lahar transit can now be applied to better representative descriptions of natural topography, with the expectation of improved hazard predictions. Using an elementary model of lahar transport dynamics, we have developed a mathematical treatment of lahar propagation over digital topography. Our results show that flow depths and transit times depend on the cumulative effects of changes in local slope along the flow path. These cumulative effects can be significant in predicting lahar advance rates and transit times. In adapting the continuum model to digital topography, we treat the changes in elevation between each adjacent pair of elevations as contiguous inclined planes and establish new boundary conditions sequentially for all downstream intervals to satisfy both local and total volume conservation requirements. Thus, we are able to derive transit times and the evolution of flow velocity and depth profile as a function of distance, x, and time, t. To illustrate the usefulness of this approach, we have applied the model using parameters typical of large volume (10~6 to 10~7 m~3), long runout (25-50 km) lahars at Mt. Ruapehu, New Zealand. By discretizing an analog topography model into N equal-sized intervals, we demonstrate that as N increases, the predicted transit time over the digital topography decreases asymptotically. Several hundred intervals are required to achieve convergence, thus yielding estimates of the minimum resolution of the digital topography (～10 m vertical, ～250 m horizontal) required to give accurate transit-time assessments. We also show that one cannot simply model irregular topography as a drop in elevation over a runout distance without risking significant errors in transit-time predications. The result that transit-time predictions decrease with increasing topographic resolution has significant implications for both hazard assessment and the ability to provide timely warnings to communities in the flow paths of lahars.
机译：火山泥石流或火山泥由于其快速定位，较长的跳动距离和巨大的破坏潜力而构成重大危险。因此，对提前率和水深的准确了解对于缓解多发地区的危害至关重要。随着数字地形数据可用性的提高，现在可以将拉哈尔过境模型应用于自然地形的更好的代表性描述，并期望得到更好的危害预测。使用拉哈尔运输动力学的基本模型，我们开发了对数字地形上拉哈尔传播的数学处理。我们的结果表明，流动深度和渡越时间取决于沿流动路径的局部坡度变化的累积影响。这些累积效应可能对预测拉哈前进速度和渡越时间具有重要意义。在使连续体模型适应数字地形时，我们将相邻的每对高程之间的高程变化视为连续的倾斜平面，并为所有下游间隔依次建立新的边界条件，以满足局部和总体积守恒的要求。因此，我们能够根据距离x和时间t得出渡越时间以及流速和深度剖面的演变。为了说明这种方法的有效性，我们使用了典型的大山峰（10〜6至10〜7〜7 m〜3），长跳动（25-50 km）拉哈斯的典型参数。新西兰鲁阿佩胡。通过将模拟地形模型离散化为N个相等大小的间隔，我们证明了随着N的增加，在数字地形上的预计渡越时间渐近地减少。需要几百个间隔才能达到收敛，因此得出了数字地形的最小分辨率（垂直〜10 m，水平〜250 m）的估计值，以进行准确的渡越时间评估。我们还表明，一个人不能简单地将不规则地形建模为跳动距离上的高程下降，而不会冒着运输时间预测的重大错误的风险。渡越时间的预测随着地形分辨率的提高而降低，这对危害评估以及向拉哈斯流径中的社区提供及时预警的能力都具有重大意义。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号