Augmentation of WRF-Hydro to simulate overland-flow- and streamflow-generated debris flow susceptibility in burn scars
Augmentation of WRF-Hydro to simulate overland-flow- and streamflow-generated debris flow susceptibility in burn scars
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DOI：
10.5194/nhess-22-2317-2022
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发表时间：
2022-07
影响因子：
4.6
通讯作者：
Chuxuan Li;A. Handwerger;Jiali Wang;Wei Yu;Xiang Li;N. Finnegan;Yingying Xie;G. Buscarnera;D. Horton
中科院分区：
文献类型：
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作者：
Chuxuan Li;A. Handwerger;Jiali Wang;Wei Yu;Xiang Li;N. Finnegan;Yingying Xie;G. Buscarnera;D. Horton
抽象的。在被山火烧毁的陡峭地形中，强烈的降雨会产生大量径流，从而引发极具破坏性的泥石流。然而，使用以物理为基础的工具准确描述和预测被烧毁地区的泥石流易感性的能力仍然有限。在这里，我们增强了天气研究和预报水文建模系统(WRF-HYDRO)，以模拟陆上和沟道化水流，并评估区域范围内火灾后泥石流的易感性。我们使用高分辨率天气雷达得出的降水和再分析数据进行后播模拟，以驱动非燃烧基线和燃烧伤疤敏感性实验。我们的模拟集中在2021年1月，当时一条大气河流在大瑟尔的一处野火烧伤伤疤内引发了大量泥石流-其中一条摧毁了加州著名的1号高速公路。与基线相比，我们的烧伤伤疤模拟产生了总流量和峰值流量的显著增加，降雨开始和峰值流量之间的滞后时间缩短，这与附近美国地质调查局(USGS)的流量计站点的水流观测一致。对于位于模拟烧伤疤痕区域的404个集水区，与基线相比，中位数集水区归一化峰值流量增加了∼450%。集水面积归一化峰值流量异常高的集水区与灾后现场和遥感泥石流观测结果吻合较好。我们认为，我们的区域火灾后泥石流易感性分析表明，WRF-HELDRO是一种引人注目的基于物理的新工具，其用途可以通过耦合到泥沙侵蚀和输送模型和/或基于集合的业务天气预报来进一步扩展。鉴于我们的增强版WRF-Hydro的高保真性能，以及它在概率危险预测中的潜在用途，我们主张继续开发和应用于火灾后水文和自然灾害评估。
Abstract. In steep wildfire-burned terrains, intense rainfall can produce large runoff that can trigger highly destructive debris flows. However, the ability to accurately characterize and forecast debris flow susceptibility in burned terrains using physics-based tools remains limited. Here, we augment the Weather Research and Forecasting Hydrological modeling system (WRF-Hydro) to simulate both overland and channelized flows and assess postfire debris flow susceptibility over a regional domain. We perform hindcast simulations using high-resolution weather-radar-derived precipitation and reanalysis data to drive non-burned baseline and burn scar sensitivity experiments. Our simulations focus on January 2021 when an atmospheric river triggered numerous debris flows within a wildfire burn scar in Big Sur – one of which destroyed California's famous Highway 1. Compared to the baseline, our burn scar simulation yields dramatic increases in total and peak discharge and shorter lags between rainfall onset and peak discharge, consistent with streamflow observations at nearby US Geological Survey (USGS) streamflow gage sites. For the 404 catchments located in the simulated burn scar area, median catchment-area-normalized peak discharge increases by ∼ 450 % compared to the baseline. Catchments with anomalously high catchment-area-normalized peak discharge correspond well with post-event field-based and remotely sensed debris flow observations. We suggest that our regional postfire debris flow susceptibility analysis demonstrates WRF-Hydro as a compelling new physics-based tool whose utility could be further extended via coupling to sediment erosion and transport models and/or ensemble-based operational weather forecasts. Given the high-fidelity performance of our augmented version of WRF-Hydro, as well as its potential usage in probabilistic hazard forecasts, we argue for its continued development and application in postfire hydrologic and natural hazard assessments.