Spatial and temporal variability in precipitation, land use, and river channels introduce uncertainty in flood estimates and pose challenges for floodplain management and mitigation. Yet, standard deterministic methods for quantifying flood hazards and evaluating risk assume stationarity in a nonstationary world and fail to account for uncertainties as they translate to flood hazards. A need exists for improved methods to portray flood hazards that incorporate uncertainty and enable integrated water management. This paper presents novel techniques for evaluating flood hazards through probabilistic flood inundation maps that reflect uncertainty quantified through Monte-Carlo analyses of model inputs and parameters. These techniques represent a first in simultaneously varying discharge, friction parameters, and channel change in probabilistic floodplain mapping while maintaining the high level of detail implemented in regulatory hydraulic models. This study evaluated four methods for quantifying the 1 % annual exceedance probability flood, including a nonstationary approach, at an urban watershed in Charlotte, North Carolina, USA. The range of variability in flood extents resulting from Monte-Carlo simulations was spatially variable, and the likelihood of inundation revealed areas of elevated or hidden risk that were not revealed by deterministic regulatory flood hazard boundaries. The nonstationary approach indicates a significant increase in flood hazards and suggests that the regulatory floodplain boundary underestimates and miscommunicates its intended risk status. A simplified approach for estimating uncertainty in flood hazards closely matched ensemble results, providing managers a practical method for conducting uncertainty analysis. These techniques can aid floodplain management by accounting for the inherent uncertainty in model estimates and the potential nonstationary behavior of flood hazards.

降水，土地利用和河道的时空变化会带来洪水估计的不确定性，并为洪泛区的管理和缓解带来挑战。但是，用于量化洪灾危害和评估风险的标准确定性方法在非平稳世界中假设平稳，并且无法解释不确定性，因为不确定性会转化为洪灾危害。需要一种改进的方法来描绘洪水隐患，该方法具有不确定性并能够进行综合的水管理。本文介绍了通过概率洪水淹没图来评估洪水危害的新技术，该图反映了通过模型输入和参数的蒙特卡洛分析量化的不确定性。这些技术代表着同时改变排放，摩擦参数，概率洪泛区映射中的通道和通道更改，同时保持在监管水力模型中实现的高细节水平。这项研究评估了美国北卡罗来纳州夏洛特市一个城市流域的四种量化年度超出概率洪水的方法，包括一种非平稳方法。蒙特卡罗模拟得出的洪水范围的变化范围在空间上是可变的，淹没的可能性揭示了确定性的监管洪水灾害边界未揭示的高风险或隐患区域。非平稳方法表明洪灾危险显着增加，并表明监管洪泛区边界低估并错误传达了其预期的风险状态。估算洪灾灾害不确定性的简化方法与总体结果非常吻合，为管理人员提供了进行不确定性分析的实用方法。这些技术可以通过考虑模型估计中的固有不确定性和洪水危害的潜在非平稳行为来帮助洪泛区管理。