Surface Water Flood Maps (FRM_FH_SURFACE_WATER_VELOCITY_L)

The following probabilities are available for surface water flooding: - High - 10 year return period - Medium - 200 year return period - Low - 200 year return period plus climate change using the UKCP09 high emissions scenario for the 2080s.The surface water hazard maps show (where available): - Flood extent - Flood depth - Flood velocities where appropriate. Velocity is presented, where appropriate; this is determined by considering the confidence in input data, modelling method and impact. It is currently represented as one of four bandsThe climate change scenario has been defined by United Kingdom Climate Projection 2009 (UKCP09) predictions for 2080 high emissions 95%ile predictions. Medium and low probability flood events were selected for consistency with return periods used in Scottish Planning Policy, whereas the high probability was chosen as it is reflective of observed events experienced over the last few decades.本次公开的地表积水灾害（surface water flooding）概率分级如下： - 高概率：重现期10年 - 中概率：重现期200年 - 低概率：采用2080年代英国气候预估2009（United Kingdom Climate Projection 2009，UKCP09）高排放情景下的气候变化修正后的200年重现期事件 地表积水灾害风险图（若有提供）包含以下内容： - 淹没范围（flood extent） - 淹没水深（flood depth） - 适宜场景下的洪水流速（flood velocities） 洪水流速仅在适宜场景下予以展示；是否展示流速需综合考量输入数据可信度、建模方法及影响评估结果，目前流速分为四个等级区间。 本次采用的气候变化情景基于UKCP09针对2080年高排放情景下95%分位数的预测结果。中、低概率洪水事件的选取标准与苏格兰规划政策（Scottish Planning Policy）所采用的重现期规范保持一致，而高概率事件的选取则贴合近数十年来实际观测到的洪水事件特征。