Following an unprecedented drought, Australia's 2019/2020 “Black Summer” fire season caused severe damage, gravely impacting both humans and ecosystems, and increasing susceptibility to other hazards. Heavy precipitation in early 2020 led to flooding and runoff that entrained ash and soil in burned areas, increasing sediment concentration in rivers, and reducing water quality. We exemplify this hazard cascade in a catchment in New South Wales by mapping burn severity, flood, and rainfall recurrence; estimating changes in soil erosion; and comparing them with river turbidity data. We show that following the extreme drought and wildfires, even moderate rain and floods led to undue increases in soil erosion and reductions in water quality. While natural risk analysis and planning commonly focuses on a single hazard, we emphasize the need to consider the entire hazard cascade, and highlight the impacts of ongoing climate change beyond its direct effect on wildfires.

中文翻译：

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澳大利亚2019/2020黑色夏季山火之后的级联危害

在经历了前所未有的干旱之后，澳大利亚的2019/2020年“黑色夏天”火灾季节造成了严重破坏，严重影响了人类和生态系统，并增加了对其他危害的敏感性。2020年初的强降水导致洪水和径流，烧毁地区的灰烬和土壤被夹带，增加了河流中的泥沙浓度，并降低了水质。我们通过绘制烧伤严重程度，洪水和降雨复发来举例说明新南威尔士流域的这种危害级联。估算土壤侵蚀的变化；并将其与河流浊度数据进行比较。我们表明，在极端干旱和野火之后，即使是中度降雨和洪水也导致土壤侵蚀过度增加和水质下降。虽然自然风险分析和计划通常只关注单一危害，