City Catchment Analysis Tool – CityCAT-is a novel software system for rapid assessment of combined pluvial and fluvial flood risk using a unique combination of: efficient software architecture throughout and especially in the numerical part; use of standard, readily available data sets; efficient algorithms for grid generation; and robust and accurate solutions of the flow equations. It is based on advanced software architecture and accurate solutions for complex free-surface flow over the terrain distinguishing between permeable and impermeable surfaces and taking into account effects of man-made features such as buildings as obstacles to flow. The software is firstly rigorously validated with demanding test cases based on analytical solutions and laboratory studies. Then the unique capability for assessment of the effectiveness of specific flood alleviation interventions across large urban domains, such as roof storage on buildings or introduction of permeable surfaces, is demonstrated.

城市集水量分析工具–CityCAT是一种新颖的软件系统，可通过以下独特组合快速评估河流和河流洪水的综合风险：贯穿整个系统，尤其是在数字方面，高效的软件体系结构；使用标准的，易于获得的数据集；高效的网格生成算法；以及流量方程的鲁棒而精确的解决方案。它基于先进的软件体系结构和针对复杂的自由表面流的准确解决方案，可在地形上区分可渗透和不可渗透表面，并考虑到人造特征（例如建筑物）对流动的阻碍。该软件首先基于分析解决方案和实验室研究，通过要求苛刻的测试用例进行了严格验证。