Post-tropical cyclone Ida (2021) flood map for New York City’s Jamaica Bay watershed

We present the first spatially continuous flood map of Hurricane Ida, which covers the Jamaica Bay watershed in New York City. This dataset represents a research effort to simulate the impact of Hurricane Ida in a coupled coastal framework, providing an estimated flood depth map. This interpolated flood map was developed using modeled peak water elevations combined with a high-resolution 30 cm DEM.

Key Considerations:
The model’s 20 cm root-mean-squared error represents the uncertainty in flood depths and is based on a calibration process that utilized two storms and high watermarks at 18 locations. Furthermore, the dataset was created with simplified hydrodynamic modeling on an approximately 50-meter resolution grid that neglects the presence of buildings and does not explicitly represent the stormwater sewer system. A calibrated spatially- and temporally constant “drain rate” represents the stormwater system drainage and infiltration across the domain. These simplifications were made to streamline the model but may lead to localized biases, particularly in areas with complex drainage and diverse land use. During extreme events like Ida, where stormwater systems can be overwhelmed, these assumptions are likely to have less impact.

For more detailed insights and methodology, please refer to the accompanying paper (see related links below).

本报告呈现了首张飓风伊达的空间连续洪水分布图，该图覆盖了纽约市的长岛湾流域。本数据集反映了在耦合海岸框架中模拟飓风伊达影响的研究努力，提供了洪水深度的估计图。此插值洪水图是基于模拟的峰值水位与高分辨率30厘米数字高程模型相结合而开发的。关键考量因素包括：该模型20厘米均方根误差代表了洪水深度的不确定性，并基于利用两次风暴和18个地点的高水位标定过程。此外，该数据集在约50米分辨率的网格上采用简化的水动力模型创建，忽略了建筑物的存在，并且未明确表示雨水排水系统。一个校准后的空间和时间恒定的‘排水速率’代表了流域内雨水系统的排水和渗透。这些简化是为了简化模型，但可能导致局部偏差，尤其是在排水复杂和土地利用多样化的区域。在类似伊达这样的极端事件中，当雨水系统可能被淹没时，这些假设的影响可能较小。有关更详细的见解和方法，请参阅随附的论文（见下方的相关链接）。