Dateline: Grand Forks, ND. March 13, 2009

The National Weather Service is predicting a 50-ft surge in Red river around Grand Forks, ND. I wanted to play around with flood scenarios in Depiction.

I started a 15-sq mile Depiction centered around Grand Forks, ND. The default NED 30 elevation data downloaded from Depiction’s quick start was not very useful. A 30-ft flood was wiping out the entire downtown area. So, I downloaded the 1/9 arc second NED elevation data from seamless.usgs.gov (check out the following URL for more details: http://www.depiction.com/node/128). Things got a whole lot easier. The 1/9 arc second data captures details such as the flood-control levees around the banks of the Red river.

I tried three flood levels – 20, 30, and 38 feet. Beyond that, pretty much the whole depiction area was under water. Local residents and emergency workers with knowledge of the area could, perhaps, supply additional details via adding elements such as ‘Water Barrier’. This would supply the missing pieces that are unavailable in the NED elevation data. Anyway, this is what I got.

A close up view of the inundation in the Lincoln drive neighborhood is below. The 20-ft baseline flood is shown in the background. Inside the revealer, we see the 38-ft flood in orange and the 1/9 arc second NED elevation data (in pink).

I invite potential Depiction users in the Grand Forks/Fargo region to download our trial copy and tell us where the Depiction flood element reflects reality accurately and where it does not. In the latter case, we’d be interested to know if the addition of water barriers (remember that the barriers can have positive or negative heights) gets you closer to reality. Send us a note (info@depiction.com) if you’d like us to publish this file online for easy access. Good luck with Depiction usage and, more importantly, with the impending flood.