River Flood Maps (FRM_FH_RIVER_VELOCITY_H)

These maps have been produced to meet SEPA’s duty to publish flood hazard maps as set out in the Flood Risk Management (Scotland) Act 2009. The maps show where there is a risk of flooding from the sea, from rivers and from surface water.The following probabilities are available for river flooding: - High - 10 year return period - Medium - 200 year return period - Low - 1000 year return period and 200 year return period plus climate change using the UKCP09 high emissions scenario for the 2080s.The river hazard maps show (where available): - Flood extent - Flood depth - Flood velocities where appropriate. The climate change scenario has been defined by United Kingdom Climate Projection 2009 (UKCP09) predictions for 2080 high emissions 95%ile predictions. 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 bandsMedium 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.本批洪水危险性地图（Flood Hazard Map）的制作，旨在履行苏格兰环境保护局（Scottish Environment Protection Agency，SEPA）依据《2009年洪水风险管理（苏格兰）法案》（Flood Risk Management (Scotland) Act 2009）所规定的发布洪水危险性地图的法定义务。这批地图涵盖了海洋、河流及地表水引发洪水的风险区域分布。 针对河流洪水，共提供以下四类概率场景： - 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：包含两类场景，分别为1000年一遇重现期场景，以及基于英国气候预测2009（United Kingdom Climate Projection 2009，UKCP09）2080年代高排放情景构建的、叠加气候变化影响的200年一遇重现期场景 河流危险性地图将展示以下信息（如可获取）： - 洪水淹没范围（Flood Extent） - 洪水水深（Flood Depth） - 适宜场景下的洪水流速（Flood Velocities） 该气候变化情景的设定依据为英国气候预测2009（UKCP09）针对2080年代高排放情景的95百分位预测结果。 仅在适宜场景下才会展示洪水流速，其展示与否需综合考量输入数据可信度、建模方法及影响评估结果。当前洪水流速被划分为四个等级之一。中、低概率洪水场景的选取标准与苏格兰规划政策（Scottish Planning Policy）中采用的重现期规范保持一致，而高概率场景的选取则贴合近数十年来实际观测到的洪水事件特征。