Rain-on-Grid (RoG) modelling is an increasingly popular approach within the storm risk management, in which the hydrological and hydrodynamic flood processes are modelled entirely within the 2D hydrodynamic model. Contrarily to what was done in the context of flood propagation in rivers, at the present time no systematic benchmarking study of the software packages implementing this approach is available in the literature. The need of benchmarking studies related to the RoG approach is becoming ever more important for HEC-RAS 2D (HR2D), the use of which has been rapidly increasing in the last few years, as further testified by very recent papers explicitly focussed on this research issue. However, there is still a lack of studies that clearly show the suitability of this software package as a reliable fully integrated hydrologic-hydrodynamic model. Therefore, the novelty introduced by this paper is the benchmarking of HR2D for RoG simulations, analysing several situations representing most of the applications related to “storm-event” hazard assessment. Specifically, after the analysis of ideal cases, which gave the opportunity to carefully assess the accuracy of the numerical schemes for RoG simulations, practical applications were considered to face some challenging issues related to the analysis of rainfall/runoff in urbanized areas and actual basins, including the numerical treatment of buildings and the computation of infiltration losses within hydrodynamic computations. The HR2D results were compared to analytical solutions, when available, experimental data and numerical solutions of a numerical code developed by the authors. The results shown in the paper highlight the potential but also the limitations of this software package, providing evidence to scientists and technicians about those situations for which reliable results are expected but also indications on specific aspects that need improvements so as to increase the model accuracy.

Rain-on-Grid (RoG) 建模是风暴风险管理中越来越流行的方法，其中水文和水动力洪水过程完全在二维水动力模型中进行建模。与在河流洪水传播背景下所做的相反，目前在文献中没有关于实现这种方法的软件包的系统基准研究。与 RoG 方法相关的基准研究的需求对于 HEC-RAS 2D (HR2D) 变得越来越重要，其使用在过去几年中迅速增加，最近明确关注这项研究的论文进一步证明了这一点问题。然而，仍然缺乏研究清楚地表明该软件包作为可靠的完全集成的水文-水动力模型的适用性。因此，本文引入的新颖之处在于 RoG 模拟的 HR2D 基准测试，分析了代表与“风暴事件”危害评估相关的大多数应用的几种情况。具体而言，在对理想情况进行分析后，有机会仔细评估 RoG 模拟数值方案的准确性，实际应用被认为面临一些与城市化地区和实际流域的降雨/径流分析相关的具有挑战性的问题，包括建筑物的数值处理和水动力计算中渗透损失的计算。HR2D 结果与解析解（如果可用）、实验数据和作者开发的数值代码的数值解进行了比较。