Flood maps are created by combining hydraulic model results with high-accuracy ground information. Field surveys and LiDAR remote sensing are used to collect river and floodplain elevations,...
Description
Flood maps are created by combining hydraulic model results with high-accuracy ground information. Field surveys and LiDAR remote sensing are used to collect river and floodplain elevations, channel cross section data, bridge and culvert information, and flood berm details. A hydrology assessment using recorded and historic flow measurements is typically used to estimate river flows for a wide range of possible open water floods with different chances of occurring each year. When appropriate, an ice jam frequency analysis is undertaken. All this information is used to build a hydraulic model of a river system, which is calibrated using highwater marks and aerial imagery from past floods to ensure that results for the different flood flows being mapped are reasonable. Flood inundation maps show areas at risk for different sized floods, including ice jam floods in some communities. These maps also identify areas that could be flooded if berms or other flood control structures fail and...