Flood Analysis

Sometimes running processes in ArcGIS can get repetitive. In the event someone is running the exact same process multiple times however, a little extra time spent building a tool in ModelBuilder could save hours of work overall.

 

The layout continues to be a work in progress as I try to optimize large scale printing in anticipation of my capstone. To the left is an evolution of various iterations of the poster before I got to the final document available at the bottom as a PDF. (After finding a template available online in Powerpoint format there were a number of variations with different degrees of detail, trying to find a balance between presentation on a monitor and blowing it up to the size of a poster. Though I decided to try and import into ArcGlobe to find an appropriate coastline, the size that program exports at is a pixelated mess at the scale and extent desired. I continue to try and find a simple way to zoom in and restich all the component images resolution suitable for printing.)

 

(Text from poster below)

 

Introduction:

•ArcGIS has a toolbox filled with processes for analysis.

•Using the built-in “ModelBuilder,” GIS users can build diagrams (like an object-oriented programming language/Play-Doh Fun Factory) to run a sequence of processes as a single-run tool.

•This could be valuable for anyone performing the same type of analysis multiple times or to run a process that can be sent to peers.

 

Objectives:

•To determine the number of tax parcels found within a floodplain (an area that has extreme risk of flooding during times of high flow.)

•To establish potential flood zones (areas within a certain buffer around the floodplain areas) and determine the number of tax parcels at risk.

 

Methods:

•Though not strictly necessary, I performed the analysis manually to determine expected values.These steps were reviewed with multiple peers running the same analysis on different computer builds..

• Then I generated a workflow to replicate these steps, adding user parameters to account for future iterations. (Identifying the floodplain and property shapefiles  involved in the process, where the outcome would be saved, in what projection would best suit a different geographic setting, and  the size of the zone buffer.)

 

Analysis:

•The entire model can be exported as a graphic workflow demonstrating every variable, procedure operated upon them, and intermediate processes necessary on the way to the ultimate outputs.

 

Results:

•It may take about half an hour to perform the analysis manually and something like twice that to build a model. Using this newly created tool it takes under five minutes for someone to fill in the necessary information and reach the same outputs. (this figure varies on computer processing power)

•From two simple shapefiles (tax parcels and a floodplain) the model as created automatically generates:

•a geodatabase to store the analysis,

•a feature dataset containing the two shapefile layers projected into user-designated settings,

•a parcel layer with an updated attribute table,

•and two tabular charts (one for floodzone parcels and one for floodplain parcels) indicating the total number and area of parcels in danger per potential land use.

Things worth noting:

•The map to the left is not automatically generated, but simply displays the end result of the tool.

•Parcels of land that touch the floodplain layer are outlined in red.

•Parcels within a certain number of feet (500 here though determined by tool user) from the foodplain layer are in a flood zone and outlined in yellow.

•Neither floodplain nor floodzone account for slope in this tool.

•Touching a floodplain is wholly different from being located wholly/largely within or having a centroid (representative center point) within this area.