Abstract. Compound floods are an active area of research where the complex interaction between pluvial, fluvial, coastal or groundwater flooding are analyzed. A number of studies have simulated the compound flooding impacts of precipitation, river discharge and storm surge variables with different numerical models and linking techniques. However, groundwater flooding is often neglected in flood risk assessments due to its sporadic frequency - as most regions have water tables sufficiently low that do not exacerbate flooding conditions -, isolated impacts and considerably less severity in respect to other types of flooding. This paper presents a physically-based, loosely-coupled modelling framework using FLO-2D and MODFLOW-2005 that is capable to simulate surface-subsurface water interactions to represent compound flooding events in North Miami. FLO-2D, responsible of the surface hydrology and infiltration processes, transfers the infiltration volume as recharge to MODFLOW-2005 until the soil absorption capacity is exceeded, while MODFLOW-2005 return exchange flow to the surface when groundwater heads are higher than the surface depth. The model calibration is based on three short-lived storm events that as individual processes represent minimum flooding conditions but in combination with pre-existing high-water table levels results in widespread flooding across the study area. Understanding groundwater flood risk is of particular interest to low-elevation coastal karst environments as the sudden emergence of the water table at ground surface can result in social disruption, adverse effects to essential services and damage infrastructure. Results are validated using FEMA’s severe repetitive loss (SRL) property records and crowdsourced data. Further research should assess the exacerbated impacts of high tides and sea level rise on water tables under current and future climate projections.

中文翻译：

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降雨-地下水相互作用的复合洪水建模框架

摘要。复合洪水是一个活跃的研究领域，其中分析了洪水、河流、沿海或地下水洪水之间复杂的相互作用。许多研究使用不同的数值模型和连接技术模拟了降水、河流流量和风暴潮变量的复合洪水影响。然而，在洪水风险评估中，地下水泛滥经常被忽视，因为它的频率是零星的——因为大多数地区的地下水位足够低，不会加剧洪水状况——与其他类型的洪水相比，其影响是孤立的，而且严重程度要低得多。本文提出了一个使用 FLO-2D 和 MODFLOW-2005 的基于物理的松耦合建模框架，该框架能够模拟地表-地下水相互作用，以表示北迈阿密的复合洪水事件。FLO-2D，负责地表水文和入渗过程，将入渗量作为补给转移到 MODFLOW-2005 直到超过土壤吸收能力，而当地下水水头高于地表深度时，MODFLOW-2005 返回地表交换流量。模型校准基于三个短暂的风暴事件，这些事件作为单个过程代表最低洪水条件，但与预先存在的高水位水平相结合，导致整个研究区域发生大范围洪水。了解地下水洪水风险对低海拔沿海岩溶环境特别重要，因为地表地下水位的突然出现可能导致社会破坏、对基本服务的不利影响和破坏基础设施。结果使用 FEMA 的严重重复性损失 (SRL) 财产记录和众包数据进行验证。进一步的研究应该在当前和未来的气候预测下评估高潮和海平面上升对地下水位的加剧影响。