Tuesday, October 13, 2015

Rainfall Model: NetLogo

Now whats seems like a long time ago, we where inspired to by  the NetLogo Grand Canyon Model and created a similar model in GeoMason. Now we have returned to NetLogo to test its ability to handle GIS data. Below you can see our attempt. The model is based on importing a geotiff of the National Elevation Dataset at 1 arc second from the National Map of Crater Lake, Oregon. After which water is added (which could be considered loosely as agents) and flows from high to low elevations, if the water cannot flow over the surface, it pools up.

The first movie below acts as a verification exercise about the basic functioning of the model (i.e. did we build the model right?). Here we have three different map types. The first being flat, the second being a cone and the third being a hill. The idea with these map types is to ensure the basic functioning of the model is correct.

After we were happy with the model, the Crater Lake example was implemented. As the movie below shows, over time, Crater Lake slowly fills up until the water breaches the caldera rim which allows the water to flow out. An extra addition to the model is the addition of erosion. Whereby as water flows over the surface, it picks up some sediment (in this case 1 unit of elevation) and when it stops moving, it deposits the sediment. As a result the terrain in the area changes. 

While carrying out this exercise, we also thought about testing NetLogo's 3D capacity with respect to creating geographically explicit agent-based models. The movie below shows the results.

More information about the models in this post can been seen on Yang Zhou's website. Also the models can be downloaded from GitHub. We hope you enjoy.

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