Intersecting with then without a buffer in ModelBuilder

Buffer Up and Intersect: ModelBuilder’s Dynamic Duo

ModelBuilder in ArcGIS? Think of it as your digital workbench for spatial analysis. It lets you string together geoprocessing tools like LEGO bricks, automating tasks that would otherwise take ages. And two of the most fundamental blocks in that kit are the Buffer and Intersect tools. Mastering these is like learning to ride a bike – once you get it, you can go anywhere!

First up, the Buffer tool. Imagine drawing a line around something on a map – that’s essentially what it does. It creates a zone of a specified distance around your chosen features, whether they’re points, lines, or polygons. Think of it as creating a “safety zone” or an area of influence. You can use it to see which houses are within a certain distance of a proposed new highway, or to map the potential impact zone of a chemical spill.

Now, the Buffer tool isn’t just a one-size-fits-all deal. It’s got options galore! You can set a fixed distance, or you can even use an attribute field to vary the buffer distance based on the characteristics of each feature. For example, you might want to create larger buffers around schools than around parks. And what about overlapping buffers? You can choose to keep them separate or merge them into one big blob – useful for simplifying your analysis. Plus, if you’re buffering lines, you can specify whether you want the buffer on both sides, just the left, or just the right. Neat, huh? And don’t forget to choose the right method (Planar or Geodesic), especially if you’re working with large areas. I once made the mistake of using Planar for a statewide analysis, and let’s just say the results were… off. Lesson learned!

Next, we have the Intersect tool. This one’s all about finding overlaps. It’s like putting two transparencies on top of each other and seeing where the colors mix. The Intersect tool identifies areas where features from different layers share the same space. Only the overlapping portions make it into the output, along with all the juicy attributes from the original layers.

So, when would you use this? Well, imagine you have a layer of zoning districts and a layer of floodplains. Intersecting them would show you which areas are both within a specific zoning district and at risk of flooding – critical information for urban planning. Or, say you want to know which properties are located within a particular watershed. Intersect is your friend!

Now, here’s where the magic happens: combining Buffer and Intersect. This is a super common workflow. Let’s say you want to find all the houses within 100 meters of a highway. First, you’d buffer the highway to create a 100-meter zone around it. Then, you’d intersect that buffer with the layer of houses. Voila! You’ve got a list of all the houses that meet your criteria.

But what if you just want to find overlaps without considering proximity? No problem! Just skip the buffer step and use the Intersect tool directly. This is perfect for those zoning district/floodplain scenarios I mentioned earlier.

Here are a few extra tips to keep in mind when using Buffer and Intersect in ModelBuilder:

• Parameterize, parameterize, parameterize! Turn those input feature classes and buffer distances into model parameters. This makes your model way more flexible and reusable.
• Name things clearly. Trust me, you’ll thank yourself later when you’re trying to decipher what “Output_FC_1” actually is.
• Geometry matters. Make sure your input feature classes have compatible geometry types for the Intersect tool.
• Coordinate systems are your friends. Use a projected coordinate system for accurate buffer calculations, especially over large areas.
• Explode those multi-parts! The Intersect tool can sometimes create multi-part features. If that’s not what you want, use the “Explode Multi-part Features” tool to break them up.

So, there you have it: a whirlwind tour of the Buffer and Intersect tools in ModelBuilder. Master these, and you’ll be well on your way to becoming a spatial analysis ninja! Now go forth and analyze!