Model builder in Arc was used to create a model that would take property parcel data along with floodplain data and run an analysis that could be used to determine what parcels are within a floodplain and are at risk of being flooded in a flood event. Along with determining what parcels are in the floodplain, the model also finds what parcels are within a set distance of the floodplain that could also be flooded in a flood event. This distance is set by the user.
Figure 1
To run the model there are six required parameters that must be meet. Figure 1 shows the parameters that are required to run the model. These include the output directory as to where the user would like the geodatabase to be created. The tax parcel data along with the floodplain polygon for the area that the user would like to analyze. The land use type field form the parcel attributes. The floodplain buffer distance that the user would like and the coordinate system for the area being analyzed.
Figure 2
Figure 3
To build the model, a workflow is created with three types of elements. Geoprocessing elements are the tools that are used for geographic or tabular data. These are the squares in the workflow. Variables are the ovals and are a value or data. If there is a P next to the field, then it is a required parameter. The third element are the connectors that connect variables to the tools. Figure 2 shows the compleat workflow for this model. Figure 3 is a zoomed in section of the workflow.
Figure 4
When the model runs it starts the analysis by selecting all of the parcels that with in and intersect the floodplain. This creates a layer of all parcels within the floodplain. This is data is then reclassified with a 2 to show they are at greater risk for flooding. A summary statistics is then created for these parcels. A table is then created using the summary statistics segmented by land use categories. The final analysis for the model is to identify all of the parcels that are within a given distance of a floodplain. The model then creates a layer of these parcels and reclassifies them as a 1 to show less potential for flooding. A summary statistics is then created for these parcels and a table is then created from that. Figure 4 shows a portion of the attribute table for parcels with 1 and 2. Null values are everything out side of the analysis.
Figure 5
Figure 5 shows the parcels with the floodplain from the analysis. Figure 6 is a zoomed in to a portion of the map to show things more clearly. Figure 7 shows the same area with parcels designate with a 2 (greatest risk of flooding) symbolized red and parcels with a 1 (within 500 feet of the floodplain) symbolized yellow. The null value parcels are symbolized green. The background has been changed from white.
Figure 6
Figure 7
