Surface Water Flood Maps (FRM_FH_SURFACE_WATER_VELOCITY_M)

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.地表积水（surface water flooding）灾害的概率等级划分如下： - 高概率：10年一遇重现期 - 中概率：200年一遇重现期 - 低概率：2080年代采用英国气候预测2009（UKCP09）高排放情景下的气候变化影响叠加200年一遇重现期洪水 地表积水灾害风险图将展示以下可获取的内容（若适用）： - 淹没范围 - 淹没水深 - 适宜场景下的淹没流速。流速的展示需结合输入数据置信度、建模方法与影响进行判定，当前将其划分为四个等级之一。 本次研究采用的气候变化情景，基于英国气候预测2009（UKCP09）针对2080年代高排放情景的95%分位数预测结果。中、低概率洪水事件的选取与苏格兰规划政策中采用的重现期标准保持一致，而高概率事件的选取则反映了近数十年间实际观测到的灾害事件特征。