Statewide RCA

The floodplain condition assessment was mostly automated with an ArcGIS Tool BOX, however, to derive the floodplain connectivity layer, some manual geoprocessing was required. First, a valley bottom polygon was required for the analysis. In addition, the most comprehensive transportation (road and railroad) layers was obtained. Using the road/railroad network overlaid on top of the valley bottom polygon, the valley bottom polygon was split everywhere there was a road/railroad. These acted as places where the river was cut off from its floodplain by manmade barriers. Validation was necessary as to make sure all disconnected areas were captured. Some additional cuts were made to the polygon to make sure portions that should be disconnected actually were disconnected. The tool used four inputs: 1. a segmented stream network (500m segments), 2. a floodplain connectivity polygon, 3. a LANDFIRE EVT layer, and, 4. a LANDFIRE BPS layer. The output results in a condition .txt file that can then be joined to the stream network output to display the condition of each segment.