Surface Water Flood Maps (FRM_FH_SURFACE_WATER_VELOCITY_H)

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.本次可获取的地表洪水（surface water flooding）概率分级如下： - 高概率：10年一遇重现期（return period） - 中概率：200年一遇重现期 - 低概率：基于200年一遇重现期，结合英国气候预测2009（UKCP09）高排放情景下2080年代的气候变化影响进行修正。 地表洪水灾害风险地图（如可获取）将展示以下内容： - 洪水淹没范围 - 洪水水深 - 适宜场景下的洪水流速。流速是否予以展示，需结合输入数据可信度、建模方法与影响效应综合判定，当前将流速划分为四个等级之一。 本次采用的气候变化情景（climate change scenario）基于英国气候预测2009（UKCP09）针对2080年高排放情景的第95百分位预测结果。中、低概率洪水事件的选取与苏格兰规划政策（Scottish Planning Policy）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洪水事件特征。