I am looking to generate flood plain polygons to represent 20 and 100 year flood zones, in the most accurate and efficient way possible, given the following datasets:
- River cross section polylines
- River flow polylines (center lines between opposing shorelines)
- 20 year and 100 year elevation values for the vertices of each cross section
- A digital elevation model (raster with an elevation value for each pixel) of the land surface
Here is my proposed methodology so far:
- Form polygons delimiting each section, the river center line and inland areas well beyond the flood plain
- For each polygon formed in the previous step, extract the intersecting raster surface (Extract by Mask)
- Isolate the pixels of the DEM that are less than or equal to the flood elevation (20 and 100 year) value for the section using the Reclassify tool
- Perform a raster (reclassified raster from previous step) to vector (polygons) to form floodplains between each section.
- Merge the polygons together to form a continuous floodplain
I am looking for insight and suggestions to produce the most accurate results possible given the available data.
I have access to ArcGIS and the Spatial Analyst and 3D Analyst extensions.