Abstract. Riverine flood risk studies require the identification of areas prone to potential flooding. This process can be based on either (hydrologically-derived) flood hazard maps or (topography-based) hydrogeomorphic floodplain maps. In this paper, we derive and compare riverine flood exposure from three global products: a hydrogeomorphic floodplain map (GFPLAIN) and two flood hazard maps (JRC and GAR). We find an average spatial agreement between these maps of around 30% at river basin level on a global scale. This agreement is highly variable across model combinations and geographic conditions, influenced by climatic humidity, river volume, topography, and coastal proximity. Contrary to expectations, the agreement between the two flood hazard maps is lower compared to their agreement with the hydrogeomorphic floodplain map. We also map riverine flood exposure for 26 countries across the Global South, by intersecting these maps with three human population maps (GHS, HRSL and WorldPop). The findings of this study indicate that hydrogeomorphic floodplain maps can be a valuable way of producing high-resolution maps of flood-prone zones to support riverine flood risk studies, but caution should be taken in regions that are dry, steep, very flat or near the coast.

中文翻译：

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全球河流洪水风险–水文地理泛滥平原地图与洪水灾害地图相比如何？

摘要。河流洪水风险研究要求确定容易发生潜在洪水的区域。此过程可以基于（水文派生的）洪灾灾害图或（基于地形的）水文地貌洪泛区图。在本文中，我们从三个全球性产品中得出并比较了河流洪水的暴露程度：水文地貌洪泛区图（GFPLAIN）和两个洪水灾害图（JRC和GAR）。我们发现，在全球范围内，这些地图之间在流域水平上的平均空间一致性约为30％。该协议在各种模型组合和地理条件之间变化很大，受气候湿度，河流流量，地形和沿海邻近地区的影响。与预期相反，两个洪水灾害图之间的一致性比其与水文地貌洪泛区图的一致性低。我们还通过将这些地图与三幅人口图（GHS，HRSL和WorldPop）相交，绘制了全球南方26个国家的河流洪水泛滥图。这项研究的结果表明，水文地貌洪泛区图可能是制作易发洪水区高分辨率图的重要方法，以支持河流洪水风险研究，但在干燥，陡峭，非常平坦或附近的地区应谨慎行事。海岸。