Risk of Flooding from Surface Water

The surface water flood maps give an indication of the broad areas likely to be at risk of surface water flooding. This includes flooding that takes place from the surface runoff generated by rainwater (including snow and other precipitation) that:
(a) is on the surface of the ground (whether or not it is moving), and
(b) has not yet entered a watercourse, drainage system or public sewer.
The Flood Map for Surface Water pick out natural drainage channels, rivers, low areas in floodplains, and flow paths between buildings. But it does not indicate flooding caused by local rainfall. It does not show flooding that occurs from overflowing watercourses, drainage systems or public sewers caused by catchment-wide rainfall events or river flow. A national model has been run for 1 in 30, 1 in 100 and 1 in 1000 year rainfall events. It has been modelled on a 2 metre square grid. Lead Local Flood Authorities were consulted and where available locally held model outputs have been incorporated into the maps.
This dataset has been superseded by the new National Flood Hazard Maps 2019 - NRW_DS124790

地表水洪水图展示了可能遭受地表水洪水风险的大面积区域。这包括由雨水（包括雪和其他降水）产生的地表径流所引起的洪水，其中：(a) 水位于地面表面（无论是否流动），且(b) 水尚未进入水道、排水系统或公共下水道。地表水洪水图突出了自然排水渠道、河流、洪泛区低地以及建筑之间的水流路径。然而，它并不表示由局部降雨引起的洪水，也不显示由流域降雨事件或河流流量导致的溢出洪水。国家模型针对30年一遇、100年一遇和1000年一遇的降雨事件进行了运行。模型基于2米见方的网格进行模拟。在必要时，已咨询当地主要地方洪水管理机构，并将当地持有的模型输出纳入地图中。本数据集已被2019年国家洪水风险图NRW_DS124790所替代。